Alphatec (ATEC) 10-K 17 Mar 20 2019 FY Annual report Financial data

Document and Entity Information

Document and Entity Information - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Mar. 09, 2020	Jun. 30, 2019
Cover [Abstract]
Entity Registrant Name	ALPHATEC HOLDINGS, INC.
Entity Central Index Key	0001350653
Current Fiscal Year End Date	--12-31
Entity Filer Category	Accelerated Filer
Document Type	10-K
Trading Symbol	ATEC
Document Period End Date	Dec. 31, 2019
Document Fiscal Year Focus	2019
Document Fiscal Period Focus (Q1,Q2,Q3,FY)	FY
Amendment Flag	false
Entity Well-known Seasoned Issuer	No
Entity Current Reporting Status	Yes
Entity Voluntary Filers	No
Entity Common Stock, Shares Outstanding		62,994,221
Entity Public Float			$ 126.2
Entity Emerging Growth Company	false
Entity Small Business	true
Entity Shell Company	false
Entity File Number	000-52024
Entity Tax Identification Number	20-2463898
Entity Address, Address Line One	5818 El Camino Real
Entity Address, City or Town	Carlsbad
Entity Address, State or Province	CA
Entity Address, Postal Zip Code	92008
City Area Code	760
Local Phone Number	431-9286
Document Annual Report	true
Document Transition Report	false
Entity Incorporation, State or Country Code	DE
Entity Interactive Data Current	Yes
Title of 12(b) Security	Common Stock, par value $0.0001 per share
Security Exchange Name	NASDAQ
Documents Incorporated by Reference	DOCUMENTS INCORPORATED BY REFERENCE The following documents (or parts thereof) are incorporated by reference into the following parts of this Form 10-K: Certain information required in Part III of this Annual Report on Form 10-K is incorporated from the Registrant’s Proxy Statement for the 2020 Annual Meeting of Stockholder.

CONSOLIDATED BALANCE SHEETS

CONSOLIDATED BALANCE SHEETS - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Current assets:
Cash	$ 47,113	$ 29,054
Accounts receivable, net	16,150	15,095
Inventories, net	34,854	28,765
Prepaid expenses and other current assets	9,880	2,030
Withholding tax receivable from officer		350
Current assets of discontinued operations	321	242
Total current assets	108,318	75,536
Property and equipment, net	19,722	13,235
Right-of-use asset	1,860
Goodwill	13,897	13,897
Intangibles, net	25,605	26,408
Other assets	493	347
Noncurrent assets of discontinued operations	53	54
Total assets	169,948	129,477
Current liabilities:
Accounts payable	7,772	4,399
Accrued expenses	26,416	22,316
Current portion of long-term debt	489	3,276
Current portion of lease liability	1,314
Current liabilities of discontinued operations	399	621
Total current liabilities	36,390	30,612
Long-term debt, less current portion	53,448	42,299
Operating lease liability, less current portion	925
Other long-term liabilities	11,951	15,389
Redeemable preferred stock, $0.0001 par value; 20,000 shares authorized at December 31, 2019 and 2018; 3,319 shares issued and outstanding at December 31, 2019 and 2018	23,603	23,603
Commitments and contingencies
Stockholders’ equity:
Common stock, $0.0001 par value; 200,000 authorized; 61,718 shares issued and 61,400 outstanding at December 31, 2019, net of 318 unvested shares and 43,518 shares issued and 43,368 shares outstanding, net of 150 unvested shares at December 31, 2018	6	4
Treasury stock, 2 shares, at cost	(97)	(97)
Additional paid-in capital	606,558	523,525
Shareholder note receivable	(5,000)	(5,000)
Accumulated other comprehensive income	1,088	1,064
Accumulated deficit	(558,924)	(501,922)
Total stockholders’ equity	43,631	17,574
Total liabilities and stockholders’ equity	169,948	129,477
Series A Convertible Preferred Stock
Stockholders’ equity:
Convertible preferred stock
Series B Convertible Preferred Stock
Stockholders’ equity:
Convertible preferred stock

CONSOLIDATED BALANCE SHEETS (Pa

CONSOLIDATED BALANCE SHEETS (Parenthetical) - $ / shares	Dec. 31, 2019	Dec. 31, 2018
Redeemable preferred stock, par value (dollars per share)	$ 0.0001	$ 0.0001
Redeemable preferred stock, shares authorized	20,000,000	20,000,000
Redeemable preferred stock, shares issued	3,319,000	3,319,000
Redeemable preferred stock, shares outstanding	3,319,000	3,319,000
Common stock, par value (dollars per share)	$ 0.0001	$ 0.0001
Common stock, shares authorized	200,000,000	200,000,000
Common stock, shares issued	61,718,000	43,518,000
Common stock, shares outstanding	61,400,000	43,368,000
Common stock, unvested shares	318,000	150,000
Treasury stock, shares	2,000	2,000
Series A Convertible Preferred Stock
Convertible preferred stock, par value (dollars per share)	$ 0.0001	$ 0.0001
Convertible preferred stock, shares authorized	15,000	15,000
Convertible preferred stock, shares issued	0	4,000
Convertible preferred stock, shares outstanding	0	4,000
Series B Convertible Preferred Stock
Convertible preferred stock, par value (dollars per share)	$ 0.0001	$ 0.0001
Convertible preferred stock, shares authorized	45,000	45,000
Convertible preferred stock, shares issued	0	0
Convertible preferred stock, shares outstanding	0	0

CONSOLIDATED STATEMENTS OF OPER

CONSOLIDATED STATEMENTS OF OPERATIONS - USD ($) shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Revenues:
Revenues	$ 113,427	$ 91,694
Cost of revenues	35,833	28,457
Gross profit	77,594	63,237
Operating expenses:
Research and development	13,849	9,853
Sales, general and administrative	101,714	72,640
Litigation-related	8,549	5,683
Amortization of intangible assets	698	738
Transaction-related		1,550
Gain on settlement		(6,168)
Restructuring	60	1,381
Total operating expenses	124,870	85,677
Operating loss	(47,276)	(22,440)
Other expense:
Other expense, net	(9,865)	(7,139)
Loss on debt extinguishment		(590)
Total other expense	(9,865)	(7,729)
Loss from continuing operations before taxes	(57,141)	(30,169)
Income tax benefit	(239)	(1,361)
Loss from continuing operations	(56,902)	(28,808)
Loss from discontinued operations, net of applicable taxes	(100)	(167)
Net loss	(57,002)	(28,975)
Recognition of beneficial conversion feature - Series B Preferred Stock		(13,488)
Net loss attributable to common shareholders	$ (57,002)	$ (42,463)
Loss per share, basic and diluted:
Continuing operations	$ (1.09)	$ (0.82)
Net loss per share, basic and diluted	$ (1.09)	$ (1.20)
Shares used in calculating basic and diluted net loss per share	52,234	35,315
United States Product
Revenues:
Revenues	$ 108,242	$ 83,656
International Supply Agreement
Revenues:
Revenues	$ 5,185	$ 8,038

CONSOLIDATED STATEMENTS OF COMP

CONSOLIDATED STATEMENTS OF COMPREHENSIVE LOSS - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Statement Of Income And Comprehensive Income [Abstract]
Net loss	$ (57,002)	$ (28,975)
Foreign currency translation adjustments related to continuing operations	24	(29)
Comprehensive loss	$ (56,978)	$ (29,004)

CONSOLIDATED STATEMENTS OF STOC

CONSOLIDATED STATEMENTS OF STOCKHOLDERS' EQUITY - USD ($) $ in Thousands	Total	SafeOp Surgical, Inc.	SafeOp Surgical, Inc.Milestone 1 and Milestone 2	Series A Convertible Preferred Stock	Series B Convertible Preferred Stock	Common stock	Common stockSafeOp Surgical, Inc.	Common stockSafeOp Surgical, Inc.Milestone 1 and Milestone 2	Additional paid-in capital	Additional paid-in capitalSafeOp Surgical, Inc.	Additional paid-in capitalSafeOp Surgical, Inc.Milestone 1 and Milestone 2	Shareholder note receivable	Treasury stock	Accumulated other comprehensive income (loss)	Accumulated deficit
Balance at Dec. 31, 2017	$ (26,658)					$ 2			$ 436,803			$ (5,000)	$ (97)	$ 1,093	$ (459,459)
Balance, shares at Dec. 31, 2017				5,000		19,857,000
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Stock-based compensation	5,649								5,649
Common stock issued for conversion of Series A preferred stock, shares				(1,000)		14,986,000
Issuance of warrants in conjunction with Squadron Term Loan	1,708								1,708
Issuance and conversion of preferred stock into common stock, net of offering costs	42,610					$ 2			42,608
Recognition of beneficial conversion feature -Series B Preferred Stock and SaleOp Convertible Notes									13,488						(13,488)
Common stock issued for employee stock purchase plan and stock option exercises	666								666
Common stock issued for employee stock purchase plan and stock option exercises, shares						258,000
Common stock issued for vesting of restricted stock awards, net of shares repurchased for tax liability, shares						248,000
Common stock issued for warrant exercises, net of issuance costs	8,628								8,628
Common stock issued for warrant exercises, net of issuance costs. shares						4,311,000
Issuance of common stock and warrants for the acquisition of SafeOp		$ 12,529								$ 12,529
Issuance of common stock and warrants for the acquisition of SafeOp, shares							$ 3,265
Issuance of common stock for acquisition			$ 1,446								$ 1,446
Issuance of common stock for acquisition, shares							443,421	443,000
Foreign currency translation adjustments	(29)													(29)
Net loss	(28,975)			$ 0	$ 0										(28,975)
Balance at Dec. 31, 2018	17,574					$ 4			523,525			(5,000)	(97)	1,064	(501,922)
Balance, shares at Dec. 31, 2018				4,000		43,368,000
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Stock-based compensation	10,294								10,294
Common stock issued for conversion of Series A preferred stock				$ (4)
Common stock issued for conversion of Series A preferred stock, shares						1,954,000
Recognition of beneficial conversion feature -Series B Preferred Stock and SaleOp Convertible Notes	242								242
Distributor equity incentives	322								322
Distributor equity incentives, shares						75,000
Common stock issued for employee stock purchase plan and stock option exercises	1,522								1,522
Common stock issued for employee stock purchase plan and stock option exercises, shares						477,000
Common stock issued for warrant exercises, net of issuance costs	1,668								1,668
Common stock issued for warrant exercises, net of issuance costs. shares						757,000
Common stock issued for vesting of performances and restricted stock units and restricted stock awards,net of tax liability	(1,414)								(1,414)
Common stock issued for vesting of performance and restricted stock units and restricted stock awards, net of tax liability, shares						1,347,000
Issuance of common stock warrants	13,664								13,664
Issuance of common stock for public offering, net of offering costs	53,848					$ 2			53,846
Issuance of stock offering, net of offering costs, shares						12,535,000
Issuance of common stock for acquisition			$ 2,889								$ 2,889
Issuance of common stock for acquisition, shares							886,843	887,000
Foreign currency translation adjustments	24													24
Net loss	(57,002)														(57,002)
Balance at Dec. 31, 2019	$ 43,631					$ 6			$ 606,558			$ (5,000)	$ (97)	$ 1,088	$ (558,924)
Balance, shares at Dec. 31, 2019						61,400,000

CONSOLIDATED STATEMENTS OF ST_2

CONSOLIDATED STATEMENTS OF STOCKHOLDERS' EQUITY (Parenthetical) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Statement Of Stockholders Equity [Abstract]
Common and preferred stock and warrants offering costs		$ 2.6
Warrants issuance cost		$ 0.1
Common stock public offering cost	$ 3.8

CONSOLIDATED STATEMENTS OF CASH

CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Operating activities:
Net loss	$ (57,002)	$ (28,975)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation and amortization	7,578	6,789
Stock-based compensation	10,956	5,304
Amortization of debt discount and debt issuance costs	3,709	2,087
Amortization of right-of-use asset	930
Provision for doubtful accounts	242	164
Provision for excess and obsolete inventory	8,624	3,733
Deferred income tax benefit	(438)	(1,405)
Gain on settlement		(6,168)
Beneficial conversion feature from convertible notes	242
Loss on extinguishment of debt		590
Loss on disposal of instruments	127	130
Accretion to contingent consideration	289	846
Changes in operating assets and liabilities:
Accounts receivable, net	(1,298)	(396)
Inventories, net	(14,712)	(5,014)
Prepaid expenses and other current assets	186	(268)
Other assets	262	(90)
Other long-term assets	(3,308)
Accrued expenses and other	6,647	1,677
Accounts payable	6,003	16
Deferred revenue		(261)
Lease liability	2,239
Other long-term liabilities	(4,397)	(4,367)
Net cash used in operating activities	(33,121)	(25,608)
Investing activities:
Purchases of property and equipment	(13,032)	(6,514)
Cash paid for acquisition of SafeOp Surgical, Inc.		(15,103)
Cash paid for acquisition of intangible assets		(400)
Cash received from sale of equipment		348
Net cash used in investing activities	(13,032)	(21,669)
Financing activities:
Proceeds from public offering, net	53,848
Proceeds from sale of common stock, net	1,977	51,902
Borrowings under lines of credit	114,710	90,459
Repayments under lines of credit	(112,934)	(89,993)
Principal payments on capital lease obligations	(27)	(96)
Proceeds from issuance of term debt, net	9,700	34,077
Principal payments on term loan and notes payable	3,091	32,464
Net cash provided by financing activities	64,183	53,885
Effect of exchange rate changes on cash	29	(20)
Net increase in cash	18,059	6,588
Cash at beginning of year	29,054	22,466
Cash at end of year	47,113	29,054
Supplemental disclosure of cash flow information:
Cash paid for interest	5,969	5,141
Cash paid for income taxes	161	134
Supplemental disclosure of noncash investing and financing activities:
Common stock warrants issued with term loan draw	13,664	1,708
Purchases of property and equipment in accounts payable	1,275	940
SafeOp Surgical, Inc.
Adjustments to reconcile net loss to net cash used in operating activities:
Accretion to contingent consideration	300
Supplemental disclosure of noncash investing and financing activities:
Common stock and warrants issued for the acquisition of SafeOp		12,529
Common stock issued for achievement of SafeOp contingent consideration	$ 2,889	$ 1,446

The Company and Basis of Presen

The Company and Basis of Presentation	12 Months Ended
	Dec. 31, 2019
Organization Consolidation And Presentation Of Financial Statements [Abstract]
The Company and Basis of Presentation	1. The Company and Basis of Presentation The Company Alphatec Holdings, Inc. (the “Company”), through its wholly owned subsidiaries, Alphatec Spine, Inc. (“Alphatec Spine”) and SafeOp Surgical, Inc. (“SafeOp”), is a medical technology company that designs, develops, and markets technology for the treatment of spinal disorders associated with disease and degeneration, congenital deformities, and trauma. The Company markets its products in the U.S. via independent sales agents and a direct sales force. On March 6, 2018, the Company and its newly created wholly-owned subsidiary, Safari Merger Sub, Inc (“Sub”), entered into an Agreement and Plan of Merger (the “Merger Agreement”) with SafeOp, a Delaware corporation, certain Key Stockholders of SafeOp and a Stockholder Representative. Pursuant to the Merger Agreement, a reverse triangular merger (the “Merger”) was consummated on March 8, 2018, in which Sub was merged into SafeOp, with SafeOp being the surviving corporation and a wholly owned subsidiary of the Company. See Note 8 for further information. On September 1, 2016, the Company completed the sale of its international distribution operations and agreements (collectively, the “International Business”) to Globus Medical Ireland, Ltd., a subsidiary of Globus Medical, Inc., and its affiliated entities (collectively “Globus”). As a result of this transaction, the International Business has been excluded from continuing operations for all periods presented in the consolidated financial statements and is reported as discontinued operations. See Note 4 for additional information on the divestiture of the International Business. Basis of Presentation The consolidated financial statements have been prepared in accordance with generally accepted accounting principles in the United States of America ("GAAP") and include the accounts of the Company, Alphatec Spine and SafeOp. All intercompany balances and transactions have been eliminated in consolidation. The Company operates in one reportable business segment. Liquidity At each reporting period, the Company evaluates whether there are conditions or events that raise substantial doubt about the Company’s ability to continue as a going concern within one year after the date that the financial statements are issued. The Company’s evaluation entails analyzing prospective operating budgets and forecasts for expectations of the Company’s cash needs and comparing those needs to the current cash and cash equivalent balances, and availability under existing credit facilities. The Company is required to make certain additional disclosures if it concludes substantial doubt exists and it is not alleviated by the Company’s plans or when its plans alleviate substantial doubt about the Company’s ability to continue as a going concern. The Company has experienced negative operating cash flows for all historical periods presented and it expects these losses to continue into the foreseeable future as the Company continues to incur costs related to the execution of its operating plan and introduction of new products. The Company’s annual operating plan projects that its existing working capital at December 31, 2019 of $71.9 million (including cash of $47.1 million), along with available draws on its working capital credit line with MidCap and an additional $20 million in available borrowings under its credit facility with Squadron Medical Finance Solutions LLC (“Squadron”), allows the Company to fund its operations through at least one year subsequent to the date the financial statements are issued. As more fully described in Note 5, the Company’s existing credit agreements with MidCap and Squadron (collectively, the “current lenders”) include a financial covenant that requires the Company to maintain a minimum cash balance of $5.0 million. The minimum cash covenant converts to a minimum fixed charge coverage ratio beginning April 30, 2020. The Company expects that it will be unable to meet the fixed charge covenant at that time. In order to avoid a default on its existing credit agreements, the Company expects to refinance its existing debt prior to April 30, 2020, pursuant to a binding commitment letter with a new lender, as further described in Note 15. Should such re-financing not occur prior to April 30, 2020 the Company has entered into letter agreements with the current lenders, agreeing to work together in good faith to amend its existing covenants to extend the minimum cash covenant and defer the fixed charge covenant through at least April 1, 2021. The committed refinancing is subject to customary closing conditions, and, therefore, there is no guarantee that the Company will be able to successfully close such refinancing on or before April 30, 2020, or at all. In addition, if required, there is no guarantee that the Company will be able to obtain the necessary waivers or amendments from its current lenders. If the Company is unable to refinance its existing debt or is unable to secure waivers or amendments from its current lenders, the current lenders have the right to accelerate the repayment of all amounts outstanding. In addition, the Company would be required to classify its obligations under existing debt agreements in current liabilities on its consolidated balance sheet. These events would negatively impact the Company’s ability to meet its ongoing financial obligations. The Company believes the refinancing of its existing debt under its commitment letter with the new lender and/or obtaining waivers or amendments of current debt covenants is probable to occur. These factors alleviate substantial doubt about the Company’s ability to continue as a going concern. Reclassification Certain amounts in the consolidated financial statements included in our Form 10-K for the year ended December 31, 2018 have been reclassified to conform to current period's presentation. These reclassifications include stock based compensation expense, which was reclassified to correctly present employee expenses consistent with their function, out of research and development and into sales, general and administrative expense on the Company’s consolidated statements of operations. This resulted in a reclassification of $0.1 million of stock compensation expense for the year ended December 31, 2018. In addition, certain amounts in the Consolidated Statement of Cash Flow included in the Form 10-K for the year ended December 31, 2018 have been reclassified to conform to current period's presentation. None of the adjustments had any effect on the prior period net loss.

Summary of Significant Accounti

Summary of Significant Accounting Policies	12 Months Ended
	Dec. 31, 2019
Accounting Policies [Abstract]
Summary of Significant Accounting Policies	2. Summary of Significant Accounting Policies Use of Estimates The preparation of consolidated financial statements in conformity with accounting principles generally accepted in the United States of America requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities at the date of the consolidated financial statements and the reported amounts of revenues and expenses during the reporting period. Actual results could differ from those estimates. Significant items subject to such estimates and assumptions include the useful lives of property and equipment, intangibles, allowances for doubtful accounts, the valuation of share based liabilities, deferred tax assets, inventory, stock-based compensation, revenues, restructuring liabilities, income tax uncertainties, and other contingencies. Concentrations of Credit Risk and Significant Customers Financial instruments, which potentially subject the Company to concentrations of credit risk, consist primarily of cash and accounts receivable. The Company limits its exposure to credit loss by depositing its cash with established financial institutions. As of December 31, 2019, a substantial portion of the Company’s available cash funds is held in business accounts. Although the Company deposits its cash with multiple financial institutions, its deposits, at times, may exceed federally insured limits. The Company’s customers are primarily hospitals, surgical centers and distributors, and no one single customer represented greater than 10 percent of consolidated revenues and accounts receivable for any of the periods presented. Credit to customers is granted based on an analysis of the customers’ credit worthiness. Credit losses have not been significant. Revenue Recognition The Company recognizes revenue from product sales in accordance with Financial Accounting Standards Board (“FASB”) Accounting Standards Codification (“ASC”) Topic 606, Revenue from Contracts with Customers The adoption of this guidance did not have a material impact on the Company’s consolidated financial statements. The Company derives its revenues primarily from the sale of spinal surgery implants and products used in the treatment of spine disorders. The Company sells its products primarily through its direct sales force and independent distributors. Revenue is recognized when control of the promised goods is transferred to the customers, in an amount that reflects the consideration the Company expects to be entitled to in exchange for those goods. Transfer of control generally occurs when the Company receives the written acknowledgment that the product has been used in a surgical procedure or upon shipment to third-party customers who immediately accept title to such product. The Company’s accounts year Accounts Receivable, net Accounts receivable are presented net of allowance for doubtful accounts. The Company makes judgments as to its ability to collect outstanding receivables and provides allowances for a portion of receivables when collection becomes doubtful. Provisions are made based upon a specific review of all significant outstanding invoices and the overall quality and age of those invoices not specifically reviewed. In determining the provision for invoices not specifically reviewed, the Company analyzes historical collection experience. If the historical data used to calculate the allowance provided for doubtful accounts does not reflect the Company’s future ability to collect outstanding receivables or if the financial condition of customers were to deteriorate, resulting in impairment of their ability to make payments, an increase in the provision for doubtful accounts may be required. Inventories, net Inventories are stated at the lower of cost or net realizable value, with cost primarily determined under the first-in, first-out method. The Company reviews the components of inventory on a periodic basis for excess, obsolete and impaired inventory, and records a reserve for the identified items. The Company calculates an inventory reserve for estimated excess and obsolete inventory based upon historical turnover and assumptions about future demand for its products and market conditions. The Company’s biologics inventories have an expiration based on shelf life and are subject to demand fluctuations based on the availability and demand for alternative implant products. The Company’s estimates and assumptions for excess and obsolete inventory are reviewed and updated on a quarterly basis. Increases in the reserve for excess and obsolete inventory result in a corresponding increase to cost of revenues and establish a new cost basis for the part. Property and Equipment, net Property and equipment are stated at cost, net of accumulated depreciation and amortization. Depreciation is computed using the straight-line method over the estimated useful lives of the related assets, generally ranging from three to seven years. Leasehold improvements and assets acquired under capital leases are amortized over the shorter of their useful lives or the remaining terms of the related leases. Operating Lease Effective January 1, 2019, the Company adopted ASC No. 2016‑02, Leases (Topic 842) (“ASC 842”), which supersedes the current accounting for leases, using the modified retrospective transition method. The Company has elected to apply the practical expedients allowed by the standard for existing leases. The new standard, while retaining two distinct types of leases, finance and operating, (i) requires lessees to record a right-of-use (“ROU”) asset and a related liability for the rights and obligations associated with a lease, regardless of lease classification, and recognize lease expense in a manner similar to current accounting, (ii) eliminates current real estate specific lease provisions, (iii) modifies the lease classification criteria and (iv) aligns many of the underlying lessor model principles with those in the new revenue standard. The Company determines the initial classification and measurement of its ROU asset and lease liabilities at the lease commencement date and thereafter, if modified. The Company recognizes a ROU asset for its operating leases with lease terms greater than 12 months. The lease term includes any renewal options and termination options that the Company is reasonably assured to exercise. The present value of lease payments is determined by using the incremental borrowing rate for operating leases determined by using the incremental borrowing rate of interest that the Company would pay to borrow on a collateralized basis an amount equal to the lease payments in a similar economic environment. The Company applied the new guidance to its existing facility lease at the time of adoption and recognized a ROU asset of $2.4 million and operating lease liability of $2.9 million as of March 31, 2019, the initial period of adoption, and removed the previous deferred rent balance under the previous lease guidance of approximately $0.6 million. The Company entered into another facility lease for smaller office space during the third quarter of 2019 and also applied this guidance to create an additional ROU asset and operating lease liability. The two leases are presented together on the Company’s consolidated balance sheet. Rent expense for operating leases is recognized on a straight-line basis over the reasonably assured lease term based on the total lease payments and is included in research and development and general and administrative expenses in the consolidated statements of operations. Goodwill and Intangible Assets The Company’s goodwill represents the excess of the cost over the fair value of net assets acquired from its business combination with SafeOp. The determination of the value of goodwill and intangible assets arising from its business combination and asset acquisitions requires extensive use of accounting estimates and judgments to allocate the purchase price to the fair value of the net tangible and intangible assets acquired, including capitalized Intangible assets acquired in a business combination that are used for in-process research and development activities are considered indefinite lived until the completion or abandonment of the associated research and development efforts. Upon reaching the end of the relevant research and development project, the Company will amortize the acquired IPR&D over its estimated useful life or expense the acquired in-process research and development should the research and development project be unsuccessful with no future alternative use. Goodwill and IPR&D are not amortized; however, they are assessed for impairment using fair value measurement techniques on an annual basis or more frequently if facts and circumstance warrant such a review. The goodwill or IPR&D are considered to be impaired if the Company determines that the carrying value of the reporting unit or IPR&D exceeds its respective fair value. The Company performs its annual impairment analysis by comparing the Company’s estimated fair value, calculated from t he Company’s market capitalization, The Company completed its most recent annual evaluation for impairment as of December 31, 2019 and determined that no impairment existed and, consequently, no impairment charge has been recorded during the year Intangible assets with a finite life, such as acquired technology, customer relationships, manufacturing know-how, licensed technology, supply agreements and certain trade names and trademarks, are amortized on a straight-line basis over their estimated useful life, ranging from one to twenty-year period. In determining the useful lives of intangible assets, the Company considers the expected use of the assets and the effects of obsolescence, demand, competition, anticipated technological advances, changes in surgical techniques, market influences and other economic factors. For technology based intangible assets, the Company considers the expected life cycles of products which incorporate the corresponding technology. Trademarks and trade names that are related to products are assigned lives consistent with the period in which the products bearing each brand are expected to be sold. The Company evaluates its intangible assets with finite lives for indications of impairment whenever events or changes in circumstances indicate that the carrying value may not be recoverable. Factors that could trigger an impairment review include significant under-performance relative to expected historical or projected future operating results, significant changes in the manner of the Company’s use of the acquired assets or the strategy for the Company’s overall business or significant negative industry or economic trends. If this evaluation indicates that the value of the intangible asset may be impaired, the Company makes an assessment of the recoverability of the net carrying value of the asset over its remaining useful life. If this assessment indicates that the intangible asset is not recoverable, based on the estimated undiscounted future cash flows of the technology over the remaining amortization period, the Company reduces the net carrying value of the related intangible asset to fair value and may adjust the remaining amortization period. There were no impairment charges in 2019 or 2018. Impairment of Long-Lived Assets The Company assesses potential impairment to its long-lived assets when there is evidence that events or changes in circumstances indicate that the carrying amount of an asset may not be recoverable. An impairment loss is recognized when the carrying amount of the long-lived assets is not recoverable if it exceeds the sum of the undiscounted cash flows expected to result from the use and eventual disposition of the asset. Any required impairment loss is measured as the amount by which the carrying amount of a long-lived asset exceeds its fair value and is recorded as a reduction in the carrying value of the related asset and a charge to operating results. There were no impairment charges in 2019 or 2018. Warrants to Purchase Common Stock Warrants are accounted for in accordance with the applicable accounting guidance as either derivative liabilities or as equity instruments depending on the specific terms of the agreements. Liability-classified instruments are recorded at fair value at each reporting period with any change in fair value recognized as a component of change in fair value of derivative liabilities in the consolidated statements of operations. All warrants issued in 2019 and 2018 qualified for classification within stockholders’ equity and, therefore, did not require liability accounting. Fair Value Measurements The carrying amount of financial instruments consisting of cash, trade accounts receivable, prepaid expenses and other current assets, accounts payable, accrued expenses, accrued compensation and current portion of long-term debt included in the Company’s consolidated financial statements are reasonable estimates of fair value due to their short maturities. Based on the borrowing rates currently available to the Company for loans with similar terms, management believes the fair value of long-term debt approximates its carrying value. Authoritative guidance establishes a three-tier fair value hierarchy, which prioritizes the inputs used in measuring fair value as follows: Level 1: Level 2: Level 3: Aside from the warrants issued alongside the Squadron amendment that are classified within prepaid and other assets on the consolidated balance sheet, the Company does not maintain any financial assets that are considered to be Level 1, Level 2 or Level 3 instruments as of December 31, 2019. The fair value of the contingent consideration liability assumed in the SafeOp acquisition was recorded as part of the purchase price consideration of the acquisition. The contingent consideration related to the SafeOp acquisition was classified within Level 3 of the fair value hierarchy as the Company was using a probability-weighted income approach, utilizing significant unobservable inputs including the probability of achieving each of the potential milestones and an estimated discount rate related to the risks of the expected cash flows attributable to the milestones. All the contingent milestones were achieved as of December 31, 2019. During the second quarter of 2019, the Company issued a liability classified equity award to one of its executive officers. The award will be earned over a 4 year vesting period and upon a specific market condition. As the award will be cash settled, it is classified as a liability within Level 3 of the fair value hierarchy as the Company is using a probability-weighted income approach, utilizing significant unobservable inputs including the probability of achieving the specified market condition with the valuation updated at each reporting period. The full fair value of the cash settled award was $1.7 million as of December 31, 2019 and is being recognized ratably as the underlying service period is provided. The following table provides a reconciliation of liabilities measured at fair value using significant unobservable inputs (Level 3) for the year ended December 31, 2018 and 2019 (in thousands): Level 3 Liabilities Balance at December 31, 2017 $ — Contingent consideration liability recorded upon acquisition of SafeOp 3,200 Settlement of milestone #1 (1,446 ) Change in fair value measurement 846 Balance at December 31, 2018 2,600 Settlement of milestone #2 (2,889 ) Change in fair value measurement- milestone #2 289 Straight line recognition of liability classified equity award 173 Change in fair value measurement- equity award 93 Balance at December 31, 2019 $ 266 During the year ended December 31, 2019, the Company achieved the second of the two milestones related to the acquisition of SafeOp, which was settled through the issuance of 886,843 shares of the Company’s common stock. See Note 8 for further information. Research and Development Expenses Research and development expense consists of costs associated with the design, development, testing, and enhancement of the Company’s products. Research and development costs also include salaries and related employee benefits, research-related overhead expenses, fees paid to external service providers. Research and development costs are expensed as incurred. Transaction-related Expenses The Company expensed certain costs related to the SafeOp acquisition, which primarily include third-party advisory and legal fees . Litigation-related Expenses Litigation-related expenses are costs incurred for the ongoing litigation, primarily with NuVasive, Inc . See Note 6 for further information. Product Shipment Cost Product shipment costs are included in sales and marketing expense in the accompanying consolidated statements of operations. Product shipment costs totaled $4.0 million and $2.5 million for the years ended December 31, 2019 and 2018, respectively. Stock-Based Compensation The Company accounts for stock-based compensation under provisions which require that share-based payment transactions with employees be recognized in the financial statements based on their fair value and recognized as compensation expense over the vesting period. The amount of expense recognized during the period is affected by subjective assumptions, including estimates of the future volatility of the Company’s stock price, the expected term for its stock options, the number of options expected to ultimately vest, and the timing of vesting for the Company’s share-based awards. The Company uses a Black-Scholes option pricing valuation model to estimate the fair value of its stock option awards. The calculation of the fair value of the awards using the Black-Scholes option pricing model is affected by the Company’s common stock price on the date of grant as well as assumptions regarding the following: • Estimated volatility is a measure of the amount by which the Company’s common stock price is expected to fluctuate each year during the expected life of the award. The Company’s estimated volatility through December 31, 2019 was based on a weighted-average volatility of its actual historical volatility over a period equal to the expected life of the awards. • The expected term represents the period of time that awards granted are expected to be outstanding. Through December 31, 2019, the Company calculated the expected term using a weighted-average term based on historical exercise patterns and the term from option date to full exercise for the options granted within the specified date range. • The risk-free interest rate is based on the yield curve of a zero-coupon U.S. Treasury bond on the date the stock option award is granted with a maturity equal to the expected term of the stock option award. • The assumed dividend yield is based on the Company’s expectation of not paying dividends in the foreseeable future. The Company used historical data to estimate the number of future stock option forfeitures. Stock-based compensation recorded in the Company’s consolidated statements of operations is based on awards expected to ultimately vest and has been reduced for estimated forfeitures. The Company’s estimated forfeiture rates may differ from its actual forfeitures which would affect the amount of expense recognized during the period. The Company accounts for stock option grants to non-employees in accordance with provisions which require that the fair value of these instruments be recognized as an expense over the period in which the related services are rendered. Stock-based compensation expense of awards with performance conditions is recognized over the period from the date the performance condition is determined to be probable of occurring through the time the applicable condition is met. Determining the likelihood and timing of achieving performance conditions is a subjective judgment made by management which may affect the amount and timing of expense related to these share-based awards. Share-based compensation is adjusted to reflect the value of options which ultimately vest as such amounts become known in future periods. Stock-based awards with market conditions are valued using the Monte Carlo valuation technique which requires management to make significant estimates and assumptions that are not observable from the market. Stock based compensation for awards with both service and market conditions that contain one vesting date are recognized on a straight line basis over the longer of the derived service period or the requisite service period. For awards with both service and market conditions with various vesting dates, stock based compensation is recognized utilizing an accelerated expense model over the longer of the derived service period or the requisite service period. Valuation of Stock Option Awards The weighted average assumptions used to compute the stock-based compensation costs for the stock options granted during the years ended December 31, 2019 and 2018 are as follows: Year Ended December 31, 2019 2018 Risk-free interest rate 2.00 % 2.85 % Expected dividend yield — — Weighted average expected life (years) 6.09 6.08 Volatility 80.76 % 78.54 % Stock-Based Compensation Costs The compensation cost that has been included in the Company’s consolidated statements of operations for all stock-based compensation arrangements is detailed as follows (in thousands): Year Ended December 31, 2019 2018 Cost of revenues $ 146 $ 73 Research and development 752 351 Sales, general and administrative 10,058 4,880 Total $ 10,956 $ 5,304 Income Taxes The Company accounts for income taxes in accordance with provisions which set forth an asset and liability approach that requires the recognition of deferred tax assets and deferred tax liabilities for the expected future tax consequences of temporary differences between the carrying amounts and the tax bases of assets and liabilities. Valuation allowances are established when necessary to reduce deferred tax assets to the amount expected to be realized. In making such determination, a review of all available positive and negative evidence must be considered, including scheduled reversal of deferred tax liabilities, projected future taxable income, tax planning strategies, and recent financial performance. The Company recognizes interest and penalties related to uncertain tax positions as a component of the income tax provision. Beneficial Conversion Feature – Series B Preferred Stock In March 2018, the Company completed a private placement of equity securities to certain institutional and accredited investors, providing for the sale by the Company of newly designated Series B Convertible Preferred Stock, which shares of preferred stock were automatically converted into 14.3 million shares of our common stock upon approval by the Company’s stockholders. As the Series B Convertible Preferred Stock provided the holder the benefit to convert to shares of common stock, a beneficial conversion feature (“BCF”) with a calculated intrinsic fair value at issuance of $13.5 million existed as of the date the shares of Series B Convertible Preferred Stock were able to be converted into shares of common stock. This one-time, non-cash deemed dividend impacts net loss attributable to common stockholders and net loss per share on the Company’s consolidated statement of operations for the year ended December 31, 2018 Beneficial Conversion Feature – SafeOp Convertible Notes In March 2019, the Company’s convertible notes outstanding reached maturity and allowed for the noteholders to elect settlement in cash or shares of the Company’s common stock. As the Convertible Notes provided the holders the benefit to convert to shares of common stock, a BCF with a calculated intrinsic fair value at issuance of $0.2 million existed as of the date the Convertible Notes were able to be converted into shares of the Company’s common stock. Although the holders elected for cash settlement, the BCF was required to be recognized as interest expense on the Company’s consolidated statement of operations and within additional paid-in-capital within the Company’s consolidated statement of stockholders’ equity for the year ended December 31, 2019. Net Loss per Share Basic earnings per share (“EPS”) is calculated by dividing the net income or loss available to common stockholders by the weighted average number of shares of common stock outstanding for the period without consideration for common stock equivalents. Diluted EPS is computed by dividing the net income or loss available to common stockholders by the weighted average number of shares of common stock outstanding for the period and the weighted average number of dilutive common stock equivalents outstanding for the period determined using the treasury-stock method. For purposes of this calculation, common stock subject to repurchase by the Company, common stock issuable upon conversion of preferred shares, options and warrants are considered to be common stock equivalents and are only included in the calculation of diluted earnings per share when their effect is dilutive. The following table sets forth the computation of basic and diluted loss per share (in thousands, except per share data): Year Ended December 31, 2019 2018 Numerator: Net loss, basic and diluted $ (57,002 ) $ (42,463 ) Denominator: Weighted average common shares outstanding 52,520 35,402 Weighted average unvested common shares subject to repurchase (286 ) (87 ) Weighted average common shares outstanding - basic and diluted 52,234 35,315 Net loss per share, basic and diluted $ (1.09 ) $ (1.20 ) Year Ended December 31, 2019 2018 Options to purchase common stock 4,215 4,682 Warrants to purchase common stock 26,557 22,302 Series A convertible preferred stock 67 2,022 Unvested restricted stock awards 6,727 3,270 Convertible notes — 988 37,566 33,264 Recent Accounting Pronouncements Recently Adopted Accounting Pronouncements In February 2016, the FASB issued Accounting Standards Update (“ASU”) 2016-02, Leases (Topic 842), which changes several aspects of the accounting for leases, including the requirement that all leases with durations greater than twelve months be recognized on the balance sheet. The guidance is effective for annual and interim reporting periods in fiscal years beginning after December 15, 2018. The Company adopted the guidance effective January 1, 2019 and elected the optional transition method to account for the impact of the adoption with a cumulative-effect adjustment in the period of adoption and did not restate prior periods. The Company elected certain practical expedients permitted under the transition guidance. As part of the adoption, the Company recorded a ROU asset and liability upon adoption of the guidance pertaining to its long-term real estate lease for its corporate facilities. No cumulative-effect adjustment was needed. Recently Issued Accounting Pronouncements In January 2017, the FASB issued ASU 2017-04, Intangibles – Goodwill and Other In August 2018, the FASB issued ASU 2018-15, Intangibles—Goodwill and Other—Internal-Use Software (Subtopic 350-40) In November 2019, the FASB issued ASU No. 2019-08, Compensation—Stock Compensation (Topic 718) and Revenue from Contracts with Customers (Topic 606)

Balance Sheet Details

Balance Sheet Details	12 Months Ended
	Dec. 31, 2019
Balance Sheet Related Disclosures [Abstract]
Balance Sheet Details	3. Balance Sheet Details Accounts Receivable, net Accounts receivable consist of the following (in thousands): December 31, 2019 2018 Accounts receivable $ 16,436 $ 15,291 Less allowance for doubtful accounts (286 ) (196 ) Accounts receivable, net $ 16,150 $ 15,095 Inventories, net Inventories consist of the following (in thousands): December 31, 2019 2018 Raw materials $ 5,822 $ 5,813 Work-in-process 1,578 952 Finished goods 51,669 39,758 59,069 46,523 Less reserve for excess and obsolete (24,215 ) (17,758 ) Inventories, net $ 34,854 $ 28,765 Property and Equipment, net Property and equipment consist of the following (in thousands, except as indicated): Useful lives December 31, (in years) 2019 2018 Surgical instruments 4 $ 58,502 $ 54,848 Machinery and equipment 7 6,038 5,971 Computer equipment 3 3,594 3,104 Office furniture and equipment 5 1,297 1,155 Leasehold improvements various 1,761 1,765 Construction in progress n/a 496 92 71,688 66,935 Less accumulated depreciation and amortization (51,966 ) (53,700 ) Property and equipment, net $ 19,722 $ 13,235 Total depreciation expense was $6.8 million and $6.0 million for the years ended December 31, 2019 and 2018, respectively. At December 31, 2019 and 2018, assets recorded under capital leases of $0.1 million were included in the machinery and equipment balance. Amortization of assets under capital leases is included in depreciation expense. Intangible Assets, net In conjunction with the acquisition of SafeOp in March 2018, the Company recorded $21.6 million of new intangible assets. See Note 8 for further information regarding the acquisition. Intangible assets, net consist of the following (in thousands, except as indicated): Remaining Avg. Useful lives December 31, (in years) 2019 2018 Developed product technology 10 $ 26,976 $ 26,976 Intellectual property — 1,004 1,004 License agreements 1 5,536 5,536 Trademarks and trade names — 792 792 Customer-related 5 7,458 7,458 Distribution network 4 4,027 4,027 In process research and development 19 8,800 8,800 54,593 54,593 Less accumulated amortization (28,988 ) (28,185 ) Intangible assets, net $ 25,605 $ 26,408 Total expense related to amortization of intangible assets was $0.7 million and $0.8 million for the years ended December 31, 2019 and 2018, respectively. Future amortization expense related to intangible assets as of December 31, 2019 is as follows (in thousands): Year Ending December 31, 2020 $ 1,869 2021 1,888 2022 1,888 2023 1,888 2024 1,785 Thereafter 16,287 Total $ 25,605 Accrued Expenses Accrued expenses consist of the following (in thousands): December 31, 2019 2018 Commissions and sales milestones $ 5,299 $ 3,594 Payroll and payroll related 7,949 3,222 Litigation settlement obligation 4,400 4,400 Professional fees 3,945 2,637 Royalties 1,981 1,354 Restructuring and severance accruals 29 710 Taxes 82 (3 ) Interest 155 261 Acquisition related - contingent consideration - 2,600 Other 2,576 3,541 Total accrued expenses $ 26,416 $ 22,316 Other Long-Term Liabilities Other long-term liabilities consist of the following (in thousands): December 31, 2019 December 31, 2018 Litigation settlement obligation - long-term portion $ 10,712 $ 13,954 Line of credit exit fee 600 600 Tax liabilities 373 835 Other 266 - Other long-term liabilities $ 11,951 $ 15,389

Discontinued Operations

Discontinued Operations	12 Months Ended
	Dec. 31, 2019
Discontinued Operations And Disposal Groups [Abstract]
Discontinued Operations	4. Discontinued Operations In connection with the sale of the International Business, the Company entered into a product manufacture and supply agreement (the “Supply Agreement”) with Globus, pursuant to which the Company supplies to Globus certain of its implants and instruments (the “Products”), previously offered for sale by the Company in international markets at agreed-upon prices for a minimum term of three years, with the option for Globus to extend the term for up to two additional twelve month periods subject to Globus meeting specified purchase requirements. During the first quarter of 2019, Globus notified the Company that it will exercise the option to extend the agreement an additional twelve months through August 2020. In accordance with authoritative guidance, sales to Globus are reported under continuing operations as the Company has continuing involvement under the Supply Agreement. During the year ended December 31, 2019, the Company recorded $5.2 million in revenue and $4.8 million in cost of revenue from the Supply Agreement in continuing operations and during the year ended December 31, 2018, the Company recorded $8.0 million in revenue and $7.5 million in cost of revenue in continuing operations. General and administrative expenses pertaining to discontinued operations on the Company’s consolidated statements of operations were immaterial for the years ended December 31, 2019 and 2018.

Debt

Debt	12 Months Ended
	Dec. 31, 2019
Debt Disclosure [Abstract]
Debt	5. Debt MidCap Facility Agreement The Company’s Amended Credit Facility with MidCap provides for a revolving credit commitment up to $22.5 million and provided for a term loan commitment up to $5 million. As of December 31, 2019, $12.8 million was outstanding under the revolving line of credit. The principal balance outstanding under the revolving line of credit is due in December 2022. Amounts outstanding under the revolving line of credit accrues interest at the London Interbank Offered Rate As collateral for the Amended Credit Facility, MidCap has a first lien security interest in and a second lien security interest on substantially all other assets. At December 31, 2019, $0.9 million remains as unamortized debt discount related to the Amended Credit Facility on the consolidated balance sheet, which will be amortized over the remaining term of the Amended Credit Facility. The Amended Credit Facility also includes several event of default provisions, such as payment default, insolvency conditions and a material adverse effect clause, which could cause interest to be charged at a rate which is up to five percentage points above the rate effective immediately before the event of default or result in MidCap’s right to declare all outstanding obligations immediately due and payable. On March 8, 2018, the Company entered into a Seventh Amendment to the Amended Credit Facility to extend the date that the financial covenants of the Amended Credit Facility are effective from April 2018 to April 2019, and established a minimum liquidity covenant of $5.0 million effective through March 2019. On November 6, 2018, the Company entered into the Eighth Amendment to the Amended Credit Facility to extend the date that the financial covenants of the Amended Credit Facility are effective from April 2019 to April 2020, and extended the minimum liquidity covenant through March 2020. The Company was in compliance with the covenants under the Amended Credit Facility at December 31, 2019. Globus Facility Agreement On September 1, 2016, the Company and Globus entered into the Globus Facility Agreement, pursuant to which Globus loaned the Company $30 million, subject to the terms and conditions set forth in the Globus Facility Agreement. On November 7, 2018, the Company repaid in full all amounts outstanding and due under the Globus Facility Agreement. The Company made a final payment of $29.2 million to Globus, consisting of outstanding principal and accrued interest. All amounts previously recorded as debt issuance costs were recorded as a loss on debt extinguishment on the Company’s consolidated statement of operations for the year ended December 31, 2018. Squadron Credit Agreement On November 6, 2018, the Company closed a $35 million Term Loan with Squadron, a provider of debt financing to growing companies in the orthopedic industry. The net proceeds of approximately $34.1 million were used to retire the Company’s existing $29.2 million term debt with Globus. The remainder of the proceeds were used for general corporate purposes. The debt has a five-year maturity and bears interest at LIBOR plus 8% (10.0% as of December 31, 2019) per annum. The Agreement specifies a minimum interest rate of 10% and a maximum of 13% per year. Interest-only payments are due monthly through May 2021, followed by $10 million in principal payable in 29 equal monthly installments beginning June 2021 and a $25 million lump-sum payment payable at maturity in November 2023. As collateral for the Term Loan, Squadron has a first lien security interest in substantially all assets except for . The credit agreement also includes several event of default provisions, such as payment default, insolvency conditions and a material adverse effect clause, which could cause interest to be charged at a rate which is up to five percentage points above the rate effective immediately before the event of default or result in Squadron’s right to declare all outstanding obligations immediately due and payable. Furthermore, the credit agreement contains various covenants, including monthly compliance certifications and compliance with government regulations and maintenance of insurance, and prohibitions against certain specified actions, including acquiring any new equipment financings over a specified amount. The credit agreement also contains various negative covenants including a $5 million minimum liquidity requirement through March 31, 2020. The minimum liquidity covenant will be replaced by a fixed charge ratio, pursuant to which operating cash to fixed charges (as defined) must equal at least 1:1 on a rolling 12-month basis, beginning April 2020. The Company was in compliance with the covenants under the credit agreement at December 31, 2019. In connection with the initial financing, the Company issued warrants to Squadron to purchase 845,000 shares of common stock at an exercise price of $3.15 per share. The warrants have a seven-year term and are immediately exercisable. See Note 9 for further detail on the warrants. In March 2019, the Company closed on an expanded credit facility with Squadron for up to $30 million in additional secured financing. This additional financing has been made available under the Company’s existing credit facility with Squadron. The Company accounted for the amendment as a debt modification with continued amortization of the existing and inclusion of the new debt issuance costs of $0.3 million amortized into interest expense utilizing the effective interest rate method. The Company took a draw of $10.0 million of the expanded credit facility in June 2019 to be used for general corporate purposes. The additional borrowings under the credit facility will mature concurrent with the current secured financing from Squadron and bear interest at the same rate and subject to the same 10% floor and 13% ceiling. Interest-only payments are due monthly through May 2021, followed by principal payable in 29 equal monthly installments beginning June 2021 and a lump-sum payment payable at maturity in November 2023. In conjunction with the first draw under the expanded credit facility, the Company issued to Squadron warrants to purchase 4,838,710 shares of the Company’s common stock at an exercise price of $2.17 per share. The warrants have a seven-year term and are immediately exercisable. The warrants were valued utilizing the Monte-Carlo simulation model as described further in Note 9 and are recorded within equity in accordance with authoritative accounting guidance and with a proportional amount, calculated by taking the draw amount divided by the total expanded credit facility, recorded as a debt discount. The total debt discount is amortized into interest expense through maturity of the debt utilizing the effective interest rate method. No additional warrants will be issued upon any future draws. The value of the additional warrants issued that are allocated to the remaining balance available for draw on the expanded credit facility were recorded as a deferred cost asset within prepaid and other assets on the consolidated balance sheet as of December 31, 2019 and are being amortized into interest expense on a ratable basis over the term of the debt. As of December 31, 2019, the debt is recorded at its carrying value of $38.6 million, net of issuance costs, including all amounts paid to third parties to secure the debt and the fair value of the warrants issued. The debt issuance costs are being amortized into interest expense over the five-year term utilizing the effective interest rate method. The total principal outstanding under the Term Loan as of December 31, 2019 is $45.0 million. Inventory Financing The Company has an Inventory Financing Agreement with a key inventory and instrument components supplier whereby the Company may draw up to $3.0 million for the purchase of inventory to accrue interest at a rate of LIBOR plus 8% subject to the same 10% floor and 13% ceiling. All principal will become due and payable upon maturity on November 6, 2023 and all interest will be paid monthly. The obligation outstanding under the Inventory Financing Agreement as of December 31, 2019 was $3.0 million. Other Debt Agreements The Company has one outstanding capital lease arrangement as of December 31, 2019. The lease bears interest at an annual rate of 6.4% and is due in monthly principal and interest installments, collateralized by the related equipment, and matures in December 2022. Long-term debt consists of the following (in thousands): December 31, 2019 2018 Amended Credit Facility with MidCap $ 12,785 $ 11,010 Inventory Financing 2,987 — Squadron Term Loan 45,000 35,000 Notes payable 457 296 Convertible note — 3,000 Total 61,229 49,306 Add: capital leases 101 126 Less: debt discount (7,393 ) (3,857 ) Total 53,937 45,575 Less: current portion of long-term debt (489 ) (3,276 ) Total long-term debt, net of current portion $ 53,448 $ 42,299 Principal payments on debt are as follows as of December 31, 2019 (in thousands): Year Ending December 31, 2020 $ 458 2021 4,483 2022 20,471 2023 35,817 2024 and thereafter — Total 61,229 Add: capital lease principal payments 101 Less: debt discount (7,393 ) Total 53,937 Less: current portion of long-term debt (489 ) Long-term debt, net of current portion $ 53,448

Commitments and Contingencies

Commitments and Contingencies	12 Months Ended
	Dec. 31, 2019
Commitments And Contingencies Disclosure [Abstract]
Commitments and Contingencies	6. Commitments and Contingencies Leases The Company occupies approximately 76,000 square feet of office, engineering, and research and development space in Carlsbad, California. Monthly rent is approximately $111,000 per month for the year ended December 31, 2018 and increases by approximately $3,000 per month each year through expiration of the lease on July 31, 2021. On December 4, 2019, the Company entered into a new lease agreement for a new headquarters location which will consist of 121,541 square feet of office, engineering, and research and development space in Carlsbad, California. The term of the new lease is currently anticipated to commence November 15, 2020 and terminate November 30, 2030, subject to two (2) sixty (60) month options to renew. The Company will recognize a ROU asset and liability upon taking control of the premises, currently anticipated to be the lease commencement date. Base rent under the new building lease for the first twelve months of the term will be $195,000 per month subject to full abatement during months two through ten. Base rent for the second year of the term will be $244,115 per month and thereafter will increase annually by 3%. At the beginning of each exercised option period, base rent will be adjusted to the market rental value, and thereafter will increase annually by 3% through the end of such option period. Capital Lease The Company has one outstanding capital lease arrangement for the lease of equipment as of December 31, 2019 that matures in 2022. The lease bears interest at a rate of 6.40% per annum, is due in monthly principal and interest installments and is collateralized by the related equipment. The total capital lease commitment outstanding as of December 31, 2019 and December 31, 2018 was $0.1 million. Operating Lease The Company leases its buildings and certain equipment under operating leases which expire on various dates through 2021. Upon the Company’s adoption of ASC 842 in January 1, 2019, the Company recognized a ROU asset and lease liability for its building lease, assuming a 10.5% discount rate. Any short-term leases defined as 12 months or less or month-to-month leases were excluded and continue to be expensed each month. Total costs associated with these leases for the year ended December 31, 2019 was immaterial. The Company determines if an arrangement is a lease at inception. The Company has operating leases for its buildings and certain equipment with lease terms of 1 year to 5.5 years, some of which include options to extend and/or terminate the lease. The exercise of lease renewal options is at the Company’s sole discretion and were not included in the calculation of the Company’s lease liability as the Company is not able to determine without uncertainty if the renewal option will be exercised. The depreciable life of assets and leasehold improvements are limited to the expected term unless there is a transfer of title or purchase option reasonably certain of exercise. The Company’s lease agreements do not contain any variable lease payments, residual value guarantees or any restrictive covenants. The Company’s ROU asset represents the right to use an underlying asset for the lease term and lease liabilities represent the obligation to make lease payments arising from the lease. Operating lease ROU assets and liabilities are recognized at commencement date of the lease or the ASC 842 adoption date, whichever is later, based on the present value of lease payments over the lease term. When readily determinable, the Company uses the implicit rate in determining the present value of lease payments, or 10.5% as of the adoption date. When leases do not provide an implicit rate, the Company uses its incremental borrowing rate based on the information available at the lease commencement date or adoption date, including the lease term. The operating lease ROU asset also includes any lease payments made and excludes lease incentives. Lease expense for lease payments is recognized on a straight-line basis over the lease term. Future minimum annual undiscounted lease payments under the Company’s operating and capital leases are as follows (in thousands): Year ending December 31, 2020 $ 1,488 2021 921 2022 42 Total undiscounted lease payments 2,451 Less: present value adjustment (212 ) Operating lease liability 2,239 Less: current portion of operating lease liability (1,314 ) Operating lease liability, less current portion $ 925 As of December 31, 2019, the Company’s remaining average lease term is years Litigation The Company is and may become involved in various legal proceedings arising from its business activities. While management is not aware of any litigation matter that in and of itself would have a material adverse impact on the Company’s consolidated results of operations, cash flows or financial position, litigation is inherently unpredictable, and depending on the nature and timing of a proceeding, an unfavorable resolution could materially affect the Company’s future consolidated results of operations, cash flows or financial position in a particular period. The Company assesses contingencies to determine the degree of probability and range of possible loss for potential accrual or disclosure in the Company’s consolidated financial statements. An estimated loss contingency is accrued in the Company’s consolidated financial statements if it is probable that a liability has been incurred and the amount of the loss can be reasonably estimated. Because litigation is inherently unpredictable and unfavorable resolutions could occur, assessing contingencies is highly subjective and requires judgments about future events. When evaluating contingencies, the Company may be unable to provide a meaningful estimate due to a number of factors, including the procedural status of the matter in question, the presence of complex or novel legal theories, and/or the ongoing discovery and development of information important to the matters. In addition, damage amounts claimed in litigation against the Company may be unsupported, exaggerated or unrelated to reasonably possible outcomes, and as such are not meaningful indicators of the Company’s potential liability. In February 2018, NuVasive, Inc. filed suit against the Company in the United States District Court for the Southern District of California ( NuVasive, Inc. v. Alphatec Holdings, Inc. et al. , Case No. 3:18-cv-00347-CAB-MDD (S.D. Cal.)), alleging that certain of the Company’s products (including components of its Battalion™ Lateral System), infringe, or contribute to the infringement of, U.S. Patent Nos. 7,819,801, 8,355,780, 8,439,832, 8,753,270, 9,833,227 (entitled “Surgical access system and related methods”), U.S. Patent No. 8,361,156 (entitled “Systems and methods for spinal fusion”), and U.S. Design Patent Nos. D652,519 (“Dilator”) and D750,252 (“Intervertebral Implant”). NuVasive seeks unspecified monetary damages and an injunction against future purported infringement. In March 2018, the Company moved to dismiss NuVasive’s claims of infringement of its design patents for failure to state a cognizable legal claim. In May 2018, the Court ruled that NuVasive failed to state a plausible claim for infringement of the asserted design patents and dismissed those claims with prejudice. The Company filed its answer, affirmative defenses and counterclaims to NuVasive’s remaining claims in May 2018. Also in March 2018, NuVasive moved for a preliminary injunction. In March 2018, the Court denied that motion without prejudice for failure to comply with the Court’s chambers rules. In April 2018, NuVasive again moved for a preliminary injunction. In July 2018, after a hearing on the matter in June 2018, the Court denied that motion on the grounds that NuVasive failed to establish either likelihood of success on the merits of its remaining claims or that it would suffer irreparable harm absent the preliminary injunction. In September 2018, NuVasive filed an Amended Complaint, asserting additional infringement claims of U.S. Patent Nos. 9,924,859, 9,974,531 and 8,187,334. The Company filed its answer, affirmative defenses and counterclaims to these new claims in October 2018. Also in October 2018, NuVasive moved to dismiss the Company’s counterclaims that intentionally had misled the U.S. Patent and Trademark Office as a means of obtaining certain patents asserted against the Company . In January 2019, the Court denied NuVasive’s motion as to all but one of the Company’s counterclaims, but granted the Company leave to amend its counterclaim to cure the dismissal. The Company amended that counterclaim in February 2019 and, that same month, NuVasive again moved to dismiss it. In March 2019, the Court denied NuVasive’s motion. NuVasive filed its Answer to the amended counterclaim in April 2019. In December 2018, the Company filed a petition with the Patent Trial and Appeal Board (“PTAB”) challenging the validity of certain claims of the ’156 and ’334 Patents . In February 2019, upon joint motion of the parties, the Court stayed all proceedings in this matter, except as noted above, pending PTAB’s determination of whether to institute inter partes of the asserted claims of the two patents at issue and vacated the trial date. In July 2019, PTAB instituted IPR of the validity of asserted claims of the two patents at issue. The Company expects PTAB to issue its final decisions regarding the validity of these claims in the second half of 2020. Also in July 2019, the parties submitted a joint statement to the Court regarding PTAB’s decisions and the parties’ respective recommendations regarding the stay of proceedings. In August 2019, the Court vacated the stay as to asserted claims concerning those patents at issue not presently before PTAB and continued the stay as to the ‘156 and ‘334 Patents. Hearing on the matters was held on March 13, 2020 and taken under submission at that time. Trial, which was originally set for April 27, 2020, has been taken off calendar due to increasing uncertainties surrounding the current public health crisis. A new trial date has not been set. The Company believes that the allegations lack merit and intends to vigorously defend all claims asserted. A liability is recorded in the consolidated financial statements if it is believed to be probable that a loss has been incurred and the amount of the loss can be reasonably estimated. in accordance with authoritative accounting guidance, Indemnifications In the normal course of business, the Company enters into agreements under which it occasionally indemnifies third-parties for intellectual property infringement claims or claims arising from breaches of representations or warranties. In addition, from time to time, the Company provides indemnity protection to third-parties for claims relating to past performance arising from undisclosed liabilities, product liabilities, environmental obligations, representations and warranties, and other claims. In these agreements, the scope and amount of remedy, or the period in which claims can be made, may be limited. It is not possible to determine the maximum potential amount of future payments, if any, due under these indemnities due to the conditional nature of the obligations and the unique facts and circumstances involved in each agreement. In October 2017, NuVasive filed a lawsuit in Delaware Chancery Court against Mr. Miles, the Company’s Chairman and CEO, who was a former officer and board member of NuVasive. The Company itself was not initially a named defendant in this lawsuit; however, on June 28, 2018, NuVasive amended its complaint to add the Company as a defendant. As of December 31, 2019, the Company has not recorded any liability on the consolidated balance sheet related to this matter. On October 12, 2018, the Delaware Court ordered that NuVasive begin advancing legal fees for Mr. Miles’ defense in the lawsuit, as well as Mr. Miles’ legal fees incurred in pursuing advancement of his fees, pursuant to an indemnification agreement between NuVasive and Mr. Miles. Royalties The Company has entered into various intellectual property agreements requiring the payment of royalties based on the sale of products that utilize such intellectual property. These royalties primarily relate to products sold by Alphatec Spine and are based on fixed fees or calculated either as a percentage of net sales or on a per-unit sold basis. Royalties are included on the accompanying consolidated statements of operations as a component of cost of revenues. As of December 31, 2019, the Company is obligated to pay guaranteed minimum royalty payments under these agreements of approximately $5.4 million through 2023 and beyond

Orthotec Settlement

Orthotec Settlement	12 Months Ended
	Dec. 31, 2019
Commitments And Contingencies Disclosure [Abstract]
Orthotec Settlement	7. Orthotec Settlement On September 26, 2014, the Company entered into a Settlement and Release Agreement, dated as of August 13, 2014, by and among the Company and its direct subsidiaries, including Alphatec Spine, Inc., Alphatec Holdings International C.V., Scient'x S.A.S. and Surgiview S.A.S.; HealthpointCapital, LLC, HealthpointCapital Partners, L.P., HealthpointCapital Partners II, L.P., John H. Foster and Mortimer Berkowitz III; and Orthotec, LLC and Patrick Bertranou, (the “Settlement Agreement”). Pursuant to the Settlement Agreement, the Company agreed to pay Orthotec, LLC $49.0 million in cash, including initial cash payments totaling $1.75 million, which the Company previously paid in March 2014, and an additional lump sum payment of $15.75 million, which the Company previously paid in April 2014. The Company agreed to pay the remaining $31.5 million in 28 quarterly installments of $1.1 million and one additional quarterly installment of $0.7 million, commencing October 1, 2014. The payments set forth above are guaranteed by Stipulated Judgments held against the Company, HealthpointCapital Partners, L.P., HealthpointCapital Partners II, L.P., HealthpointCapital, LLC, John H. Foster and Mortimer Berkowitz III and, in the event of a default, will be entered and enforced against these entities and/or individuals in that order. In September 2014, the Company and HealthpointCapital entered into an agreement for joint payment of settlement whereby HealthpointCapital has agreed to contribute $5 million to the $49 million settlement amount. The $5 million is classified within stockholders’ equity on the Company’s consolidated balance sheets due to the related party nature with HealthpointCapital and its affiliates. See Note 12 for further information. As of December 31, 2019, the Company has made installment payments in the aggregate of $40.6 million, with a remaining outstanding balance of $17.2 million (including interest). The Company has the right to prepay the amounts due without penalty. The unpaid amounts due accrue interest at the rate of 7% per year until paid in full. The accrued but unpaid interest will be paid in quarterly installments of $1.1 million (or the full amount of the accrued but unpaid interest if less than $1.1 million) following the full payment of the $31.5 million in quarterly installments described above. No interest will accrue on the accrued interest. The Settlement Agreement provides for mutual releases of all claims in the Orthotec, LLC v. Surgiview, S.A.S, et al. matter in the Superior Court of California, Los Angeles County and all other related litigation matters involving the Company and its directors and affiliates. A reconciliation of the total net settlement obligation is as follows (in thousands): December 31, 2019 December 31, 2018 Litigation settlement obligation - short-term portion $ 4,400 $ 4,400 Litigation settlement obligation - long-term portion 10,712 13,954 Total 15,112 18,354 Future Interest 2,121 3,279 Total settlement obligation, gross 17,233 21,633 Related party receivable - included in stockholders' equity (5,000 ) (5,000 ) Total settlement obligation, net $ 12,233 $ 16,633

Acquisition of SafeOp Surgical,

Acquisition of SafeOp Surgical, Inc.	12 Months Ended
	Dec. 31, 2019
Business Combinations [Abstract]
Acquisition of SafeOp Surgical, Inc.	8. Acquisition of SafeOp Surgical, Inc. On March 8, 2018, the Company acquired SafeOp, a privately-held provider of neuromonitoring technology designed to enable effective intra-operative nerve health assessment. At the time of the acquisition, SafeOp had FDA 510(k) approval for a somatosensory evoked potential (“SSEP”) monitoring technology. The Company has developed a product that will allow for both free run and triggered specific recording of muscle activity, also known as Electromyography (“EMG”). The Company received FDA clearance for SafeOp’s EMG technology in February 2019 to complement the SSEP solution, and anticipates commercialization of the combined technology solution in mid-2019. In addition to expanding the Company’s market presence in lateral spine surgery, the Company believes that the SafeOp solution will allow it to integrate neuromonitoring into its broader product portfolio and accelerate the transition to procedural integration of the entire portfolio. Under the term of the definitive merger agreement, the Company paid $15.1 million in cash and issued 3,265,132 shares of common stock. The Company paid the full $15.1 million in cash consideration during the year ended December 31, 2018. On March 8, 2018, the Company issued 2,975,209 shares of common stock valued at $9.8 million, based on the closing share price of $3.30, and issued an additional 115,621 shares of common stock during the second quarter of 2018 and the remaining 174,302 during the third quarter of 2018. In March 2018, the Company also issued $3.0 million in convertible notes that were convertible into a total of 987,578 shares of common stock, which included total interest incurred, and issued warrants to purchase 2.2 million shares of common stock at an exercise price of $3.50 per share and contain a five year life. The convertible notes matured on March 9, 2019 and were settled in cash. Upon maturity, the Company recognized the value associated with the beneficial conversion feature calculated at issuance of $0.2 million within interest expense on the Company’s consolidated statement of operations for the year ended December 31, 2019. Shares of common stock were issued upon achievement of post-closing milestones as described further below. The warrants remain outstanding as of December 31, 2019. The first of the two milestones was achieved during the year ended December 31, 2018 and resulted in the issuance of 443,421 shares of common stock as payment. The second milestone pertaining to regulatory approval was achieved and the Company issued 886,843 shares of common stock as payment during the three months ended March 31, 2019. Prior to achievement, the contingent consideration was recorded as a liability and measured at fair value using a probability-weighted income approach, utilizing significant unobservable inputs including the probability of achieving each of the potential milestones and an estimated discount rate related to the risks of the expected cash flows attributable to the milestones. The fair value of the contingent consideration, and the associated liability relating to the contingent consideration at each reporting date, was re-assessed with the changes in fair value reflected in earnings. For the year ended December 31, 2019, the fair value for the contingent consideration increased by $0.3 million due to the proximity of the achievement of the milestone. The amount was recorded within research and development expense on the consolidated statement of operations and a corresponding increase in the liability on the Company’s consolidated balance sheet. The full liability was relieved upon achievement of the remaining milestone during the period.

Equity

Equity	12 Months Ended
	Dec. 31, 2019
Equity [Abstract]
Equity	9. Equity August 2019 Offering On August 2, 2019, the Company closed the Offering in which a total of 12,535,000 shares of its common stock, were issued and sold at a price to the public of $4.60 per share. The closing of the Offering included the issuance and sale of 1,635,000 shares of the Company’s common stock, included within the total number of shares above, pursuant to the full exercise of the underwriters’ option to purchase additional shares pursuant to the Purchase Agreement. The net proceeds to the Company from the Offering were approximately $53.9 million, including the net proceeds from the option shares. Redeemable Preferred Stock The Company issued shares of redeemable preferred stock in connection with its initial public offering in June 2006. As of December 31, 2019 and 2018, the redeemable preferred stock carrying value was $23.6 million and there were 20 million shares of redeemable preferred stock authorized. The redeemable preferred stock is not convertible into common stock but is redeemable at $9.00 per share, (i) upon the Company’s liquidation, dissolution or winding up, or the occurrence of certain mergers, consolidations or sales of all or substantially all of the Company’s assets, before any payment to the holders of the Company’s common stock, or (ii) at the Company’s option at any time. Holders of redeemable preferred stock are generally not entitled to vote on matters submitted to the stockholders, except with respect to certain matters that will affect them adversely as a class, and are not entitled to receive dividends. The carrying value of the redeemable preferred stock was $7.11 per share at December 31, 2019 and 2018. The redeemable preferred stock is presented separately from stockholders’ deficit in the consolidated balance sheets and any adjustments to its carrying value up to its redemption value of $9.00 per share are reported as a dividend. Series A Convertible Preferred Stock In March 2017, the Company completed a private placement (the “2017 Private Placement”) with certain institutional and accredited investors, including certain directors, executive officers and employees of the Company (collectively, the “Purchasers”), providing for the sale by the Company of 1,809,628 shares of the Company’s common stock at a purchase price of $2.00 per share and 15,245 shares of newly designated Series A Convertible Preferred Stock at a purchase price of $1,000 per share (which shares were convertible into approximately 7,622,372 shares of common stock). Except as otherwise required by law, the holders of Series A Convertible Preferred Stock have no right to vote on matters submitted to a vote of the Company’s stockholders. During the years ended December 31, 2019 and 2018, 3,909 and 1,274 shares of Series A Preferred Stock were converted into 1,954,334 and 636,997 shares of common stock, respectively. As of December 31, 2019, there were 135 shares of Series A Convertible Preferred Stock outstanding, which are convertible into 67,338 shares of common stock. 2017 Warrants In connection with the 2017 Private Placement, the Company issued warrants to purchase up to 9,432,000 shares of the Company’s common stock at an exercise price of $2.00 per share (the “2017 Common Stock Warrants”). The Company also issued warrants to purchase common stock to the exclusive placement agents (the “2017 Banker Warrants”). The 2017 Banker Warrants were for the purchase of up to an aggregate of 471,600 shares of the Company’s common stock with substantially the same terms as the 2017 Common Stock Warrants, except that they have an exercise price equal $2.50 per share. The 2017 Common Stock Warrants and the 2017 Banker Warrants (collectively, the “2017 Warrants”) expire on June 15, 2022. The 2017 Warrants may not be exercised by the holder to the extent that the holder, together with its affiliates, would beneficially own, after such exercise more than 4.99% of the shares of the Company’s common stock then outstanding (subject to the right of the holder to increase or decrease such beneficial ownership limitation upon notice to the Company, provided that such limitation cannot exceed 9.99%) and provided that any increase in the beneficial ownership limitation shall not be effective until 61 days after such notice is delivered. In conjunction with the 2018 Private Placement described further below, during the year ended December 31, 2018, a holder of 2.4 million 2017 Warrants exercised all its 2017 Warrants at the original exercise price of $2.00 per warrant in exchange for the issuance of additional warrants. As a result of the warrant exercise, the Company received gross proceeds of $4.8 million during the year ended December 31, 2018. During the year ended December 31, 2019, there were 0.5 million 2017 Warrant exercises for total cash proceeds of $1.1 million. During the year ended December 31, 2018, excluding the $4.8 million described above, the Company received proceeds of approximately $4.0 million in connection with the exercise of approximately 1.9 million of 2017 Common Stock Warrants. As of December 31, 2019, there were 3,232,000 2017 Common Stock Warrants outstanding. There were 18,864 2017 Banker Warrant exercises during the year ended December 31, 2019 for total cash proceeds of less than $0.1 million. During the year ended December 31, 2018, 304,182 of the 2017 Banker Warrants were exercised for total cash proceeds upon exercise of $0.8 million during the period. A total of 148,554 2017 Banker Warrants remained outstanding as of December 31, 2019. All the 2017 Warrants were deemed to qualify for equity classification under authoritative accounting guidance. Series B Convertible Preferred Stock On March 8, 2018, the Company completed the 2018 Private Placement to certain institutional and accredited investors, including certain directors and executive officers of the Company, at a purchase price of $1,000 per share, 45,200 of newly designated Series B Convertible Preferred Stock, which shares of preferred stock were automatically converted into 14,349,236 shares of the Company’s common stock upon approval by the Company’s stockholders at the 2018 annual meeting of stockholders held in May 2018, and warrants to purchase up to 12,196,851 shares of common stock at an exercise price of $3.50 per share (the “2018 Common Stock Warrants”). The 2018 Common Stock Warrants became exercisable following stockholder approval at the 2018 annual meeting of stockholders, are subject to certain ownership limitations in certain cases, and expire five years after the date of such stockholder approval. The gross proceeds from the 2018 Private Placement were approximately $45.2 million. Pursuant to the terms of the purchase agreement entered into in connection with the 2018 Private Placement, from the date of the stockholder approval of the 2018 Private Placement, or May 17, 2018, through the first anniversary of the effective date of the resale registration statement related to the 2018 Private Placement, or May 11, 2019, if the Company issues any shares of common stock or common stock equivalents, subject to certain permitted exceptions, at a price below the conversion price on the date stockholder approval was obtained (a “Dilutive Issuance”), the Company is required to issue an additional number of shares of common stock to the purchasers in the 2018 Private Placement in amount equal to the number of shares of common stock such purchasers would have received if the Dilutive Issuance occurred prior to the date the Company’s stockholders approved the 2018 Private Placement. No such Dilutive Issuances occurred prior to the expiration. 2018 Warrants The 2018 Common Stock Warrants (the “2018 Warrants”) have a five year life and are exercisable for cash or by cashless exercise. Some of the 2018 Warrants may not be exercised by the holder to the extent that the holder, together with its affiliates, would beneficially own, after such exercise more than 4.99% of the shares of the Company’s common stock then outstanding (subject to the right of the holder to increase or decrease such beneficial ownership limitation upon notice to the Company, provided that such limitation cannot exceed 9.99%) and provided that any increase in the beneficial ownership limitation shall not be effective until 61 days after such notice is delivered. In addition to the 12,196,851 warrants issued in the 2018 Private Placement, the Company issued 1,800,000 warrants to an existing holder with identical terms to the 2018 Warrants, including the exercise price of $3.50. During the year ended December 31, 2019, 0.2 million of the 2018 Warrants were exercised for total proceeds of $0.6 million. No 2018 Warrants were exercised for the year ended December 31, 2018. A total of 13,770,488 of 2018 Warrants remained outstanding as of December 31, 2019. All the 2018 Warrants were deemed to qualify for equity classification under authoritative accounting guidance. Squadron Warrants As further described in Note 5, during the year ended December 31, 2018, in connection with the initial debt financing with Squadron, the Company issued warrants to purchase 845,000 shares of common stock at an exercise price of $3.15 per share. An additional 4,838,710 warrants were issued at an exercise price of $2.17 per share during the second quarter of 2019, in conjunction with the Company’s draw on the expanded credit facility for total warrants outstanding to Squadron of 5,683,710. The warrants have a seven-year term and are immediately exercisable. In accordance with authoritative accounting guidance, the warrants qualified for equity treatment upon issuance and the portion allocated to the outstanding debt was recorded as a debt discount to the face of the debt liability based on fair value to be amortized into interest expense over the life of the debt agreement. The remaining balance of the warrants was recorded as an asset included within prepaid expenses and other current assets on the consolidated balance sheet as of December 31, 2019 and is being amortized into interest expense on a ratable basis. As the warrants provide for partial price protection that allow for a reduction in the price in the event of a lower per share priced issuance, the warrants were valued utilizing a Monte Carlo simulation that considers the probabilities of future financings. The Monte Carlo model simulates the present value of the potential outcomes of future stock prices of the Company over the seven-year life of the warrants. The projection of stock prices is based on the risk-free rate of return and the volatility of the stock price of the Company and correlates future equity raises based on the probabilities provided. In December 2011, in connection with the third amendment to the Company’s former credit facility with the Silicon Valley Bank ("SVB"), finance charges totaling $0.2 million were waived in exchange for the issuance to SVB of warrants to purchase 7,812 shares of the Company’s common stock. The warrants are immediately exercisable, can be exercised through a cashless exercise, have an exercise price of $19.20 per share and have a 10-year term. As mentioned above, the Company issued Common Stock Warrants in connection with the private placement financing in March 2017 and March 2018. The warrants expire on the fifth anniversary of the date on which they were first exercisable. Further, as described in Note 8, the Company issued warrants in conjunction with the acquisition of SafeOp. In December 2017 the Company issued warrants to Mr. Miles, the Company’s Chairman and Chief Executive Officer, to purchase 1,327,434 shares of the Company’s common stock for $5 per share. The warrants have a five-year term. The warrants issued to Mr. Miles were accounted for as share based compensation, and the fair value of the warrants of approximately $1.4 million were recognized in full in the statement of operations for the year ended December 31, 2017 as the warrants were immediately vested upon issuance. A summary of all outstanding warrants is as follows: Number of Warrants Strike Price 2017 Common Stock Warrants 3,232,000 $ 2.00 2017 Banker Warrants 148,554 $ 2.50 2018 Common Stock Warrants 13,770,488 $ 3.50 Merger Warrants 2,199,682 $ 3.50 Executive 1,327,434 $ 5.00 Squadron Capital 845,000 $ 3.15 Squadron Capital 4,838,710 $ 2.17 Other 195,312 $ 3.85 Total 26,557,180

Stock Benefit Plans and Stock-B

Stock Benefit Plans and Stock-Based Compensation	12 Months Ended
	Dec. 31, 2019
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Stock Benefit Plans and Stock-Based Compensation	10. Stock Benefit Plans and Stock-Based Compensation In the third quarter of 2016, the Company adopted its 2016 Equity Incentive Plan (the “2016 Plan”), which replaced the Company’s 2005 Employee, Director and Consultant Stock Plan. On October 25, 2018, the Company’s Board of Directors adopted an amendment to the Company’s 2016 Equity Incentive Award Plan. The 2016 Plan allows for the grant of options, restricted stock, restricted stock unit awards and performance unit awards to employees, directors, and consultants of the Company. Upon its adoption, the 2016 Plan had 1,083,333 shares of common stock reserved for issuance. The Board of Directors determines the terms of the grants made under the 2016 Plan. Options granted under the 2016 Plan expire no later than ten years from the date of grant (five years for incentive stock options granted to holders of more than 10% of the Company’s voting stock). Options generally vest over a four-year period and may be immediately exercisable upon a change of control of the Company. The exercise price of incentive stock options may not be less than 100% of the fair value of the Company’s common stock on the date of grant. The exercise price of any option granted to a 10% stockholder may be no less than 110% of the fair value of the Company’s common stock on the date of grant. At December 31, 2019, 666,742 shares of common stock remained available for issuance under the 2016 Plan. The 2016 Plan will expire in May 2026. On October 4, 2016, the Company’s Board of Directors adopted the 2016 Employment Inducement Award Plan (the “Inducement Plan”). The Inducement Plan allows for the grant of options, restricted stock, restricted stock unit awards and performance unit awards to new employees of the Company by granting an award to such new employee as an inducement for such new employee to begin employment with the Company. As of December 31, 2019 the Inducement Plan had 801,099 shares of common stock reserved for issuance, which may only be granted to an employee who has not previously been an employee or member of the board of directors of the Company. The terms of the Inducement Plan are substantially similar to the terms of the Company’s 2016 Plan with two principal exceptions: (i) incentive stock options may not be granted under the Inducement Plan; and (ii) the annual compensation paid by the Company to specified executives will be deductible only to the extent that it does not exceed $1.0 million. In July 2019, the Board of Directors approved and adopted the 2019 Management Objective Strategic Incentive Plan which authorizes the Company to grant restricted stock to individuals or entities that do not qualify under the other existing equity plans. The Board of Directors authorized the grant of up to 500,000 shares of common stock with a maximum grant of 50,000 shares per participant under the plan. As of December 31, 2019, 55,000 restricted shares have been granted under the 2019 Management Objective Strategic Incentive Plan. Total expense for the plan was immaterial for the year ended December 31, 2019. The 2016 Plan, the Inducement Plan and the Management Objective Strategic Incentive Plan are collectively referred to as the Plans. Stock Options A summary of the Company’s stock option activity under the Plans and related information is as follows (in thousands, except as indicated and per share data): Shares Weighted average exercise price Weighted average remaining contractual term (in years) Aggregate intrinsic value Outstanding at December 31, 2018 4,723 $ 3.64 Granted 195 $ 4.41 Exercised (161 ) $ 2.75 Forfeited (542 ) $ 7.00 Outstanding at December 31, 2019 4,215 $ 3.27 7.80 $ 17,961 Options vested and exercisable at December 31, 2019 2,238 $ 3.71 7.40 $ 9,438 Options vested and expected to vest at December 31, 2019 4,028 $ 3.29 7.77 $ 17,177 The weighted-average grant-date fair value per share of stock options granted during the years ended December 31, 2019 and 2018 was $1.92 and $2.00, respectively. The aggregate intrinsic value of options at December 31, 2019 is based on the Company’s closing stock price on the last business day of 2019 of $7.10 per share. As of December 31, 2019, there was $3.7 million of unrecognized compensation expense for stock options which is expected to be recognized on a straight-line basis over a weighted average period of approximately 2.30 years. Restricted Stock Awards and Units The following table summarizes information about the restricted stock awards, restricted stock units and performance-based restricted units activity (in thousands, except as indicated and per share data): Shares Weighted average grant date fair value Weighted average remaining recognition period (in years) Unvested at December 31, 2018 3,270 $ 2.94 Awarded 4,802 $ 1.92 Vested (1,224 ) $ 2.83 Forfeited (121 ) $ 3.11 Unvested at December 31, 2019 6,727 $ 2.17 2.32 The weighted average fair value per share of awards granted during the years ended December 31, 2019 and 2018 was $1.92 and $2.87, respectively. As of December 31, 2019, there was $16.0 million of unrecognized compensation expense for restricted stock awards and units which is expected to be recognized on a straight-line basis over a weighted average period of approximately 2.32 years. Termination and Settlement of Elite Medical Holdings and Pac 3 Surgical Collaboration Agreement In February 2018, the Company reached a settlement agreement with Elite Medical Holdings and Pac 3 Surgical, pursuant to which the Company made a cash payment of $0.4 million as the final and total compensation under the original agreement. In addition, the parties agreed to release each other and waive any and all rights and claims arising from the original agreement. The Company recorded a gain of approximately $6.2 million during the year ended December 31, 2018, reflecting the reversal of accrued obligations previously recorded under the collaboration. 2017 Distributor Inducement Plan In December 2017, the Board of Directors approved and adopted the 2017 Distributor Inducement Plan which authorizes the Company to issue to distributors restricted shares of common stock of the Company and/or warrants to purchase the Company’s common stock. The warrants are issuable with an exercise price equal to the fair market value of the common stock on the date of issuance. Each warrant and common stock issuance is subject to a time-based or net sales-based vesting provision. The Board of Directors authorized the grant of up to 1,000,000 shares of common stock under the 2017 Distributor Inducement Plan. As of December 31, 2019, 0.3 million warrants and 92,000 shares of common stock were earned under the 2017 Distributor Inducement Plan. Total expense for the plan was $0.4 and $0.2 million for the years ended December 31, 2019 and December 31, 2018, respectively. In December 2017, the Board of Directors also authorized grant of warrants to purchase 50,000 of the Company’s common stock, and 75,000 restricted stock units to a distributor. These warrants and restricted stock units are subject to time based and net sales based vesting conditions. 2017 Development Services Plan In December 2017, the Board of Directors approved and adopted the 2017 Development Services Plan which authorizes the Company to enter into Development Services Agreements with third-party individuals or entities whereby, upon the achievement of certain Company financial and commercial revenue milestones, future royalty payments for product and/or intellectual property development work may be paid in either cash or restricted shares of Company common stock at the option of the developer. Each common stock issuance would be subject to net sales-based vesting provisions and satisfaction of applicable laws and market regulations regarding the issuance of restricted shares to such developers. The Board of Directors authorized the grant of up to 3,000,000 shares of common stock under the 2017 Development Services Plan. As of December 31, 2019, 2.4 million have been designated under the 2017 Development Services Plan, but none are deemed probable of election as of December 31, 2019. In addition, no common stock elections or cash payouts have been made as of December 31, 2019. Common Stock Reserved for Future Issuance Common stock reserved for future issuance consists of the following (in thousands): December 31, 2019 Stock options outstanding 4,215 Unvested restricted stock awards 6,727 Employee stock purchase plan 117 Series A convertible preferred stock 67 Warrants outstanding 26,557 Authorized for future grant under the Distributor and Development Services plans 3,908 Authorized for future grant under the Management Objective Strategic Incentive Plan 445 Authorized for future grant under the Plans 1,628 43,664

Income Taxes

Income Taxes	12 Months Ended
	Dec. 31, 2019
Income Tax Disclosure [Abstract]
Income Taxes	11. Income Taxes The components of the pretax income (loss) are presented in the following table (in thousands): Year Ended December 31, 2019 2018 U.S. Domestic $ (57,141 ) $ (30,169 ) Foreign (100 ) (167 ) Pretax loss from operations $ (57,241 ) $ (30,336 ) The components of the (benefit) provision for income taxes from continuing operations are presented in the following table (in thousands): Year Ended December 31, 2019 2018 Current income tax (benefit) provision: Federal $ — $ (64 ) State 207 86 Foreign — 4 Total current 207 26 Deferred income tax benefit: Federal (195 ) (1,140 ) State (251 ) (247 ) Total deferred (446 ) (1,387 ) Total income tax benefit $ (239 ) $ (1,361 ) The provision for income taxes differs from the amount of income tax determined by applying the applicable U.S. statutory federal income tax rate to pretax income (loss) from continuing operations as a result of the following differences: December 31, 2019 2018 Federal statutory rate 21.00 % 21.00 % Adjustments for tax effects of: State taxes, net 0.12 % 0.47 % Stock-based compensation 0.26 % (4.29 )% R&D credit expiration (5.96 )% — Fair market value adjustments — (0.59 )% Other permanent adjustments (0.42 )% (0.56 )% Foreign partnership liquidation 19.19 % — Federal uncertain tax positions 3.25 % 0.30 % NOL expiration (3.01 )% — Other 1.16 % (1.57 )% Valuation allowance (35.09 )% (10.25 )% Effective income tax rate 0.50 % 4.51 % Significant components of the Company’s deferred tax assets and liabilities as of December 31, 2019 and 2018 are as follows (in thousands): December 31, 2019 2018 Deferred tax assets: Accruals and reserves $ 2,730 $ 1,133 Income tax credit carryforwards 1,591 3,150 Interest 4,095 1,351 Inventory 8,625 4,959 Legal settlement 3,789 4,693 Net operating losses 53,592 45,092 Stock-based compensation 2,256 1,182 Total deferred tax assets 76,678 61,560 Valuation allowance (71,159 ) (46,578 ) Total deferred tax assets, net of valuation allowance 5,519 14,982 Deferred tax liabilities: Property and equipment (3,117 ) (21 ) Goodwill and intangibles (2,344 ) (1,972 ) Investment in foreign partnership — (13,370 ) Total deferred tax liabilities (5,461 ) (15,363 ) Net deferred tax assets (liabilities) $ 58 $ (381 ) The realization of deferred tax assets is dependent on the Company’s ability to generate sufficient taxable income in future years in the associated jurisdiction to which the deferred tax assets relate. As of December 31, 2019, a valuation allowance of $71.2 million has been established against the net deferred tax assets, as the Company has determined that it is currently not more likely than not that these assets will be realized. During the year ended December 31, 2019, the federal and state valuation allowances collectively increased by $20.1 million and $4.5 million, respectively. In determining the need for a valuation allowance, the Company considers all available positive and negative evidence, including scheduled reversals of deferred tax liabilities, projected future taxable income, tax planning strategies, and recent financial performance. The Company reached technological feasibility with respect to its in-process research and development efforts in 2019, and as such, valuation allowance was decreased as amortization of intangible asset began. There are no indefinite-lived intangible assets as of December 31, 2019. Based on the review of all positive and negative evidence, including a three-year cumulative pre-tax loss, the Company determined that a full valuation allowance should be recorded against its deferred tax assets, with the exception of the Company’s Texas Temporary Credit for Business Loss Carryforwards. There are no indefinite live assets. At December 31, 2019, the Company has unrecognized tax benefits of $2.5 million, which will affect the effective tax rate if recognized when the Company no longer has a valuation allowance offsetting its deferred tax assets. The following table summarizes the changes to unrecognized tax benefits (in thousands): Year ended December 31, 2019 2018 Unrecognized tax benefit at the beginning of the year $ 4,334 $ 4,440 Reductions as a result of lapse of applicable statute of limitations (1,882 ) (106 ) Unrecognized tax benefits at the end of the year $ 2,452 $ 4,334 The Company and its subsidiaries are subject to federal income tax as well as income tax of multiple state and foreign jurisdictions. With few exceptions, the Company is no longer subject to income tax examination by tax authorities in major jurisdictions for years prior to 2015. However, to the extent allowed by law, the taxing authorities may have the right to examine prior periods where net operating losses and tax credits were generated and carried forward and make adjustments up to the amount of the carryforwards. The Company is not currently under examination by the Internal Revenue Service, foreign or state and local tax authorities. The Company recognizes interest and penalties related to uncertain tax positions as a component of the income tax provision. As of December 31, 2019, there were no accrued interest and penalties. At December 31, 2019, the Company had federal and state net operating loss carryforwards of $205.2 million and $128.2 million, respectively, expiring at various dates beginning in 2019 through 2039. Net operating losses generated in years ending after December 31, 2017 can be carried forward indefinitely for federal and some states. At December 31, 2019, the Company had state research and development tax credit carryforwards of $3.2 million. The state research and development tax credits do not have an expiration date, and may be carried forward indefinitely. Utilization of the net operating loss and tax credit carryforwards may become subject to annual limitations due to ownership change limitations that could occur in the future as provided by Section 382 and 383 of the Internal Revenue Code of 1986, as amended (the “Internal Revenue Code”), as well as similar state provisions. These ownership changes may limit the amount of the net operating loss and tax credit carryforwards that can be utilized annually to offset future taxable income, if the Company experiences a cumulative change in ownership of more than 50% within a three-year testing period. The Company completed a formal study through the year ended December 31, 2018 and determined ownership changes within the meaning of IRC Section 382 had occurred. The Company adjusted tax attribute carry forwards and deferred tax assets accordingly. As the deferred tax assets associated with the tax attribute carry forwards were fully offset by a valuation allowance, a corresponding reduction in the Company’s valuation allowance was also recorded, resulting in no income tax impact.

Related Party Transactions

Related Party Transactions	12 Months Ended
	Dec. 31, 2019
Related Party Transactions [Abstract]
Related Party Transactions	12. Related Party Transactions In July 2016, the Company entered into a forbearance agreement with HealthpointCapital, LLC, HealthpointCapital Partners, L.P., and HealthpointCapital Partners II, L.P. (collectively, "HealthpointCapital"), pursuant to which HealthpointCapital, on behalf of the Company, paid $1.0 million of the $1.1 million payment due and payable by the Company to Orthotec on July 1, 2016 and agreed to not exercise its contractual rights to seek an immediate repayment of such amount. Pursuant to this forbearance agreement, the Company repaid this amount in September 2016. The Company and HealthpointCapital also entered into an agreement for joint payment of settlement whereby HealthpointCapital has agreed to contribute $5 million to the $49 million Orthotec settlement amount. During the second quarter of 2018, HealthpointCapital Partners, L.P., and HealthpointCapital Partners II, L.P. distributed its holdings in the Company’s common stock to its limited partners. As a result, the fund is no longer a shareholder of the Company as of December 31, 2018. The $5 million receivable from HealthpointCapital, LLC continues to be classified within stockholders’ equity on the Company’s consolidated balance sheets due to the related party nature with HealthpointCapital affiliates. Certain of the Company’s board of directors and senior management participated in the March 2017 and 2018 private placem Included on the consolidated balance sheet as of December 31, 2018 is a $0.3 million officer receivable for settlement of a tax liability related to the vesting of a restricted stock unit. A corresponding liability for the same amount is also included on the consolidated balance sheet within the accrued expenses line item. Subsequent to December 31, 2018, the amounts were settled and remitted to settle the tax liability.

Retirement Plan

Retirement Plan	12 Months Ended
	Dec. 31, 2019
Compensation And Retirement Disclosure [Abstract]
Retirement Plan	13. Retirement Plan The Company maintains an employee savings plan that qualifies as a deferred salary arrangement under Section 401(k) of the Internal Revenue Code. Under the savings plan, participating employees may contribute a portion of their pre-tax earnings, up to the Internal Revenue Service annual contribution limit. Additionally, the Company may elect to make matching contributions into the savings plan at its sole discretion of up to 4% of each individual’s compensation. Matching contributions vest after one year of service. The Company’s total contributions to the 401(k) plan were $0.6 million and $0.4 million for the years ended December 31, 2019 and 2018, respectively.

Restructuring Activities

Restructuring Activities	12 Months Ended
	Dec. 31, 2019
Restructuring And Related Activities [Abstract]
Restructuring Activities	14. Restructuring Activities In connection with the sale of the International Business (described in Note 4), the Company terminated employment agreements with several executive officers, including the chief executive officer and the chief financial officer, and commenced an employee headcount reduction program. In conjunction with the restructuring program, the Company recorded restructuring expenses related to severance liabilities and post-employment benefits. A rollforward of the accrued restructuring liability is presented below (in thousands): Balance at December 31, 2018 $ 710 Accrued restructuring charges 60 Payments (746 ) Balance at December 31, 2019 $ 24

Subsequent Event

Subsequent Event	12 Months Ended
	Dec. 31, 2019
Subsequent Events [Abstract]
Subsequent Event	15. Subsequent Event Tender Offer Agreement On February 28, 2020, the Company entered into a Tender Offer Agreement (the “Tender Offer Agreement”) with EOS Imaging S.A., a société anonyme Autorité des marches financiers Commitment Letter In connection with entry into the Tender Offer Agreement, the Company entered into a commitment letter, dated February 28, 2020 (the “Commitment Letter”), with Perceptive Credit Holdings III, LP (together with its affiliates, “Perceptive”), pursuant to which, subject to the terms and conditions set forth therein, Perceptive has committed to provide $130 million in secured debt financing, up to $60 million of which (the “Refinancing Portion”) will be made available to retire the Company’s existing credit facilities with MidCap Funding IV, LLC and Squadron Medical Finance Solutions, LLC. The remaining commitment by Perceptive to provide an additional $70 million (which may be increased to up to $100 million at the request of the Company if agreed by Perceptive in its sole discretion) in secured debt financing (the “Tender Offer Portion”) will be made available to fund the Cash Offer portion of the Offer Consideration, provided the Company may elect not to incur all or a portion of such Tender Offer Portion to the extent it is unnecessary to fund such Cash Offer amount. In the event the Company elects not to incur the Tender Offer Portion of Perceptive’s commitment, Perceptive will make available up to $15 million in secured debt financing (the “Supplemental Portion”), in addition to the Refinancing Portion, to be used for the Company’s and its subsidiaries’ general corporate and working capital needs. The funding of each of the debt facilities provided for in the Commitment Letter is subject to the satisfaction of customary conditions for facilities of such type that are set forth therein, including entry into definitive documentation reflecting the terms of the Commitment Letter and no material adverse effect with respect to EOS. Under the terms of the Commitment Letter, the Company has agreed to issue certain warrants to Perceptive representing the right to acquire ATEC Common Stock in connection with the incurrence of the Refinancing Portion (the “Refinancing Warrants”), the incurrence and use of the Tender Offer Portion to consummate the tender offer (the “Tender Offer Warrants”) and the incurrence of the Supplemental Portion (the “Supplemental Warrants” and, together with the Refinancing Warrants and Tender Offer Warrants, the “Warrants”), as applicable. The price per share for 50% of the Refinancing Warrants shall be the lower of (x) the 5-day volume weighted average price of the ATEC Common Stock (“5-day VWAP”) immediately prior to the date of the Commitment Letter and (y) the 5-day VWAP immediately prior to the closing date of the Refinancing Portion, subject to a floor of $4.60 per share (the “Base Refinancing Warrant Price”). The price per share for the remaining 50% of the Refinancing Warrants shall be equal to the Base Refinancing Warrant Price plus an additional 12.5% premium. The price per share for 50% of the Tender Offer Warrants shall be the lower of (x) the 5-day VWAP immediately prior to the date of the Commitment Letter or (y) the 5-day VWAP immediately prior to the date such Tender Offer Warrants are issued, subject to a floor of $4.60 per share (the “Base Tender Offer Warrant Price”). The price per share for the remaining 50% of the Tender Offer Warrants shall be equal to the Base Tender Offer Warrant Price plus an additional 12.5% premium. The price per share for 50% of the Supplemental Warrants shall be the lower of (x) the 5-day VWAP immediately prior to the date of the Commitment Letter or (y) the 5-day VWAP immediately prior to the date the Supplemental Portion is incurred, subject to a floor of $4.60 per share (the “Base Supplemental Warrant Price”). The price per share for the remaining 50% of the Supplemental Warrants shall be equal to the Base Supplemental Warrant Price plus an additional 12.5% premium. The Refinancing Warrants, Tender Offer Warrants and Supplemental Warrants will be exercisable into a number of shares of ATEC Common Stock representing 18.5% of the aggregate principal amount borrowed in respect of the Refinancing Portion, 9% of the aggregate principal amount borrowed in respect of the Tender Offer Portion and used to consummate the Tender Offer and 9% of the aggregate principal amount borrowed in respect of the Supplemental Portion, respectively, in each case calculated using the Base Refinancing Warrant Price, Base Tender Offer Warrant Price or Base Supplemental Warrant Price, as applicable.

Summary of Significant Accoun_2

Summary of Significant Accounting Policies (Policies)	12 Months Ended
	Dec. 31, 2019
Use of Estimates	Use of Estimates The preparation of consolidated financial statements in conformity with accounting principles generally accepted in the United States of America requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities at the date of the consolidated financial statements and the reported amounts of revenues and expenses during the reporting period. Actual results could differ from those estimates. Significant items subject to such estimates and assumptions include the useful lives of property and equipment, intangibles, allowances for doubtful accounts, the valuation of share based liabilities, deferred tax assets, inventory, stock-based compensation, revenues, restructuring liabilities, income tax uncertainties, and other contingencies.
Concentrations of Credit Risk and Significant Customers	Concentrations of Credit Risk and Significant Customers Financial instruments, which potentially subject the Company to concentrations of credit risk, consist primarily of cash and accounts receivable. The Company limits its exposure to credit loss by depositing its cash with established financial institutions. As of December 31, 2019, a substantial portion of the Company’s available cash funds is held in business accounts. Although the Company deposits its cash with multiple financial institutions, its deposits, at times, may exceed federally insured limits. The Company’s customers are primarily hospitals, surgical centers and distributors, and no one single customer represented greater than 10 percent of consolidated revenues and accounts receivable for any of the periods presented. Credit to customers is granted based on an analysis of the customers’ credit worthiness. Credit losses have not been significant.
Revenue Recognition	Revenue Recognition The Company recognizes revenue from product sales in accordance with Financial Accounting Standards Board (“FASB”) Accounting Standards Codification (“ASC”) Topic 606, Revenue from Contracts with Customers The adoption of this guidance did not have a material impact on the Company’s consolidated financial statements. The Company derives its revenues primarily from the sale of spinal surgery implants and products used in the treatment of spine disorders. The Company sells its products primarily through its direct sales force and independent distributors. Revenue is recognized when control of the promised goods is transferred to the customers, in an amount that reflects the consideration the Company expects to be entitled to in exchange for those goods. Transfer of control generally occurs when the Company receives the written acknowledgment that the product has been used in a surgical procedure or upon shipment to third-party customers who immediately accept title to such product. The Company’s accounts year
Accounts Receivable, net	Accounts Receivable, net Accounts receivable are presented net of allowance for doubtful accounts. The Company makes judgments as to its ability to collect outstanding receivables and provides allowances for a portion of receivables when collection becomes doubtful. Provisions are made based upon a specific review of all significant outstanding invoices and the overall quality and age of those invoices not specifically reviewed. In determining the provision for invoices not specifically reviewed, the Company analyzes historical collection experience. If the historical data used to calculate the allowance provided for doubtful accounts does not reflect the Company’s future ability to collect outstanding receivables or if the financial condition of customers were to deteriorate, resulting in impairment of their ability to make payments, an increase in the provision for doubtful accounts may be required.
Inventories, net	Inventories, net Inventories are stated at the lower of cost or net realizable value, with cost primarily determined under the first-in, first-out method. The Company reviews the components of inventory on a periodic basis for excess, obsolete and impaired inventory, and records a reserve for the identified items. The Company calculates an inventory reserve for estimated excess and obsolete inventory based upon historical turnover and assumptions about future demand for its products and market conditions. The Company’s biologics inventories have an expiration based on shelf life and are subject to demand fluctuations based on the availability and demand for alternative implant products. The Company’s estimates and assumptions for excess and obsolete inventory are reviewed and updated on a quarterly basis. Increases in the reserve for excess and obsolete inventory result in a corresponding increase to cost of revenues and establish a new cost basis for the part.
Property and Equipment, net	Property and Equipment, net Property and equipment are stated at cost, net of accumulated depreciation and amortization. Depreciation is computed using the straight-line method over the estimated useful lives of the related assets, generally ranging from three to seven years. Leasehold improvements and assets acquired under capital leases are amortized over the shorter of their useful lives or the remaining terms of the related leases.
Operating Lease	Operating Lease Effective January 1, 2019, the Company adopted ASC No. 2016‑02, Leases (Topic 842) (“ASC 842”), which supersedes the current accounting for leases, using the modified retrospective transition method. The Company has elected to apply the practical expedients allowed by the standard for existing leases. The new standard, while retaining two distinct types of leases, finance and operating, (i) requires lessees to record a right-of-use (“ROU”) asset and a related liability for the rights and obligations associated with a lease, regardless of lease classification, and recognize lease expense in a manner similar to current accounting, (ii) eliminates current real estate specific lease provisions, (iii) modifies the lease classification criteria and (iv) aligns many of the underlying lessor model principles with those in the new revenue standard. The Company determines the initial classification and measurement of its ROU asset and lease liabilities at the lease commencement date and thereafter, if modified. The Company recognizes a ROU asset for its operating leases with lease terms greater than 12 months. The lease term includes any renewal options and termination options that the Company is reasonably assured to exercise. The present value of lease payments is determined by using the incremental borrowing rate for operating leases determined by using the incremental borrowing rate of interest that the Company would pay to borrow on a collateralized basis an amount equal to the lease payments in a similar economic environment. The Company applied the new guidance to its existing facility lease at the time of adoption and recognized a ROU asset of $2.4 million and operating lease liability of $2.9 million as of March 31, 2019, the initial period of adoption, and removed the previous deferred rent balance under the previous lease guidance of approximately $0.6 million. The Company entered into another facility lease for smaller office space during the third quarter of 2019 and also applied this guidance to create an additional ROU asset and operating lease liability. The two leases are presented together on the Company’s consolidated balance sheet. Rent expense for operating leases is recognized on a straight-line basis over the reasonably assured lease term based on the total lease payments and is included in research and development and general and administrative expenses in the consolidated statements of operations.
Goodwill and Intangible Assets	Goodwill and Intangible Assets The Company’s goodwill represents the excess of the cost over the fair value of net assets acquired from its business combination with SafeOp. The determination of the value of goodwill and intangible assets arising from its business combination and asset acquisitions requires extensive use of accounting estimates and judgments to allocate the purchase price to the fair value of the net tangible and intangible assets acquired, including capitalized Intangible assets acquired in a business combination that are used for in-process research and development activities are considered indefinite lived until the completion or abandonment of the associated research and development efforts. Upon reaching the end of the relevant research and development project, the Company will amortize the acquired IPR&D over its estimated useful life or expense the acquired in-process research and development should the research and development project be unsuccessful with no future alternative use. Goodwill and IPR&D are not amortized; however, they are assessed for impairment using fair value measurement techniques on an annual basis or more frequently if facts and circumstance warrant such a review. The goodwill or IPR&D are considered to be impaired if the Company determines that the carrying value of the reporting unit or IPR&D exceeds its respective fair value. The Company performs its annual impairment analysis by comparing the Company’s estimated fair value, calculated from t he Company’s market capitalization, The Company completed its most recent annual evaluation for impairment as of December 31, 2019 and determined that no impairment existed and, consequently, no impairment charge has been recorded during the year Intangible assets with a finite life, such as acquired technology, customer relationships, manufacturing know-how, licensed technology, supply agreements and certain trade names and trademarks, are amortized on a straight-line basis over their estimated useful life, ranging from one to twenty-year period. In determining the useful lives of intangible assets, the Company considers the expected use of the assets and the effects of obsolescence, demand, competition, anticipated technological advances, changes in surgical techniques, market influences and other economic factors. For technology based intangible assets, the Company considers the expected life cycles of products which incorporate the corresponding technology. Trademarks and trade names that are related to products are assigned lives consistent with the period in which the products bearing each brand are expected to be sold. The Company evaluates its intangible assets with finite lives for indications of impairment whenever events or changes in circumstances indicate that the carrying value may not be recoverable. Factors that could trigger an impairment review include significant under-performance relative to expected historical or projected future operating results, significant changes in the manner of the Company’s use of the acquired assets or the strategy for the Company’s overall business or significant negative industry or economic trends. If this evaluation indicates that the value of the intangible asset may be impaired, the Company makes an assessment of the recoverability of the net carrying value of the asset over its remaining useful life. If this assessment indicates that the intangible asset is not recoverable, based on the estimated undiscounted future cash flows of the technology over the remaining amortization period, the Company reduces the net carrying value of the related intangible asset to fair value and may adjust the remaining amortization period. There were no impairment charges in 2019 or 2018.
Impairment of Long-Lived Assets	Impairment of Long-Lived Assets The Company assesses potential impairment to its long-lived assets when there is evidence that events or changes in circumstances indicate that the carrying amount of an asset may not be recoverable. An impairment loss is recognized when the carrying amount of the long-lived assets is not recoverable if it exceeds the sum of the undiscounted cash flows expected to result from the use and eventual disposition of the asset. Any required impairment loss is measured as the amount by which the carrying amount of a long-lived asset exceeds its fair value and is recorded as a reduction in the carrying value of the related asset and a charge to operating results. There were no impairment charges in 2019 or 2018.
Warrants to Purchase Common Stock	Warrants to Purchase Common Stock Warrants are accounted for in accordance with the applicable accounting guidance as either derivative liabilities or as equity instruments depending on the specific terms of the agreements. Liability-classified instruments are recorded at fair value at each reporting period with any change in fair value recognized as a component of change in fair value of derivative liabilities in the consolidated statements of operations. All warrants issued in 2019 and 2018 qualified for classification within stockholders’ equity and, therefore, did not require liability accounting.
Fair Value Measurements	Fair Value Measurements The carrying amount of financial instruments consisting of cash, trade accounts receivable, prepaid expenses and other current assets, accounts payable, accrued expenses, accrued compensation and current portion of long-term debt included in the Company’s consolidated financial statements are reasonable estimates of fair value due to their short maturities. Based on the borrowing rates currently available to the Company for loans with similar terms, management believes the fair value of long-term debt approximates its carrying value. Authoritative guidance establishes a three-tier fair value hierarchy, which prioritizes the inputs used in measuring fair value as follows: Level 1: Level 2: Level 3: Aside from the warrants issued alongside the Squadron amendment that are classified within prepaid and other assets on the consolidated balance sheet, the Company does not maintain any financial assets that are considered to be Level 1, Level 2 or Level 3 instruments as of December 31, 2019. The fair value of the contingent consideration liability assumed in the SafeOp acquisition was recorded as part of the purchase price consideration of the acquisition. The contingent consideration related to the SafeOp acquisition was classified within Level 3 of the fair value hierarchy as the Company was using a probability-weighted income approach, utilizing significant unobservable inputs including the probability of achieving each of the potential milestones and an estimated discount rate related to the risks of the expected cash flows attributable to the milestones. All the contingent milestones were achieved as of December 31, 2019. During the second quarter of 2019, the Company issued a liability classified equity award to one of its executive officers. The award will be earned over a 4 year vesting period and upon a specific market condition. As the award will be cash settled, it is classified as a liability within Level 3 of the fair value hierarchy as the Company is using a probability-weighted income approach, utilizing significant unobservable inputs including the probability of achieving the specified market condition with the valuation updated at each reporting period. The full fair value of the cash settled award was $1.7 million as of December 31, 2019 and is being recognized ratably as the underlying service period is provided. The following table provides a reconciliation of liabilities measured at fair value using significant unobservable inputs (Level 3) for the year ended December 31, 2018 and 2019 (in thousands): Level 3 Liabilities Balance at December 31, 2017 $ — Contingent consideration liability recorded upon acquisition of SafeOp 3,200 Settlement of milestone #1 (1,446 ) Change in fair value measurement 846 Balance at December 31, 2018 2,600 Settlement of milestone #2 (2,889 ) Change in fair value measurement- milestone #2 289 Straight line recognition of liability classified equity award 173 Change in fair value measurement- equity award 93 Balance at December 31, 2019 $ 266 During the year ended December 31, 2019, the Company achieved the second of the two milestones related to the acquisition of SafeOp, which was settled through the issuance of 886,843 shares of the Company’s common stock. See Note 8 for further information.
Research and Development Expenses	Research and Development Expenses Research and development expense consists of costs associated with the design, development, testing, and enhancement of the Company’s products. Research and development costs also include salaries and related employee benefits, research-related overhead expenses, fees paid to external service providers. Research and development costs are expensed as incurred.
Transaction-related Expenses	Transaction-related Expenses The Company expensed certain costs related to the SafeOp acquisition, which primarily include third-party advisory and legal fees .
Litigation-related Expenses	Litigation-related Expenses Litigation-related expenses are costs incurred for the ongoing litigation, primarily with NuVasive, Inc . See Note 6 for further information.
Product Shipment Cost	Product Shipment Cost Product shipment costs are included in sales and marketing expense in the accompanying consolidated statements of operations. Product shipment costs totaled $4.0 million and $2.5 million for the years ended December 31, 2019 and 2018, respectively.
Stock-Based Compensation	Stock-Based Compensation The Company accounts for stock-based compensation under provisions which require that share-based payment transactions with employees be recognized in the financial statements based on their fair value and recognized as compensation expense over the vesting period. The amount of expense recognized during the period is affected by subjective assumptions, including estimates of the future volatility of the Company’s stock price, the expected term for its stock options, the number of options expected to ultimately vest, and the timing of vesting for the Company’s share-based awards. The Company uses a Black-Scholes option pricing valuation model to estimate the fair value of its stock option awards. The calculation of the fair value of the awards using the Black-Scholes option pricing model is affected by the Company’s common stock price on the date of grant as well as assumptions regarding the following: • Estimated volatility is a measure of the amount by which the Company’s common stock price is expected to fluctuate each year during the expected life of the award. The Company’s estimated volatility through December 31, 2019 was based on a weighted-average volatility of its actual historical volatility over a period equal to the expected life of the awards. • The expected term represents the period of time that awards granted are expected to be outstanding. Through December 31, 2019, the Company calculated the expected term using a weighted-average term based on historical exercise patterns and the term from option date to full exercise for the options granted within the specified date range. • The risk-free interest rate is based on the yield curve of a zero-coupon U.S. Treasury bond on the date the stock option award is granted with a maturity equal to the expected term of the stock option award. • The assumed dividend yield is based on the Company’s expectation of not paying dividends in the foreseeable future. The Company used historical data to estimate the number of future stock option forfeitures. Stock-based compensation recorded in the Company’s consolidated statements of operations is based on awards expected to ultimately vest and has been reduced for estimated forfeitures. The Company’s estimated forfeiture rates may differ from its actual forfeitures which would affect the amount of expense recognized during the period. The Company accounts for stock option grants to non-employees in accordance with provisions which require that the fair value of these instruments be recognized as an expense over the period in which the related services are rendered. Stock-based compensation expense of awards with performance conditions is recognized over the period from the date the performance condition is determined to be probable of occurring through the time the applicable condition is met. Determining the likelihood and timing of achieving performance conditions is a subjective judgment made by management which may affect the amount and timing of expense related to these share-based awards. Share-based compensation is adjusted to reflect the value of options which ultimately vest as such amounts become known in future periods. Stock-based awards with market conditions are valued using the Monte Carlo valuation technique which requires management to make significant estimates and assumptions that are not observable from the market. Stock based compensation for awards with both service and market conditions that contain one vesting date are recognized on a straight line basis over the longer of the derived service period or the requisite service period. For awards with both service and market conditions with various vesting dates, stock based compensation is recognized utilizing an accelerated expense model over the longer of the derived service period or the requisite service period.
Valuation of Stock Option Awards	Valuation of Stock Option Awards The weighted average assumptions used to compute the stock-based compensation costs for the stock options granted during the years ended December 31, 2019 and 2018 are as follows: Year Ended December 31, 2019 2018 Risk-free interest rate 2.00 % 2.85 % Expected dividend yield — — Weighted average expected life (years) 6.09 6.08 Volatility 80.76 % 78.54 %
Stock-Based Compensation Costs	Stock-Based Compensation Costs The compensation cost that has been included in the Company’s consolidated statements of operations for all stock-based compensation arrangements is detailed as follows (in thousands): Year Ended December 31, 2019 2018 Cost of revenues $ 146 $ 73 Research and development 752 351 Sales, general and administrative 10,058 4,880 Total $ 10,956 $ 5,304
Income Taxes	Income Taxes The Company accounts for income taxes in accordance with provisions which set forth an asset and liability approach that requires the recognition of deferred tax assets and deferred tax liabilities for the expected future tax consequences of temporary differences between the carrying amounts and the tax bases of assets and liabilities. Valuation allowances are established when necessary to reduce deferred tax assets to the amount expected to be realized. In making such determination, a review of all available positive and negative evidence must be considered, including scheduled reversal of deferred tax liabilities, projected future taxable income, tax planning strategies, and recent financial performance. The Company recognizes interest and penalties related to uncertain tax positions as a component of the income tax provision.
Net Loss per Share	Net Loss per Share Basic earnings per share (“EPS”) is calculated by dividing the net income or loss available to common stockholders by the weighted average number of shares of common stock outstanding for the period without consideration for common stock equivalents. Diluted EPS is computed by dividing the net income or loss available to common stockholders by the weighted average number of shares of common stock outstanding for the period and the weighted average number of dilutive common stock equivalents outstanding for the period determined using the treasury-stock method. For purposes of this calculation, common stock subject to repurchase by the Company, common stock issuable upon conversion of preferred shares, options and warrants are considered to be common stock equivalents and are only included in the calculation of diluted earnings per share when their effect is dilutive. The following table sets forth the computation of basic and diluted loss per share (in thousands, except per share data): Year Ended December 31, 2019 2018 Numerator: Net loss, basic and diluted $ (57,002 ) $ (42,463 ) Denominator: Weighted average common shares outstanding 52,520 35,402 Weighted average unvested common shares subject to repurchase (286 ) (87 ) Weighted average common shares outstanding - basic and diluted 52,234 35,315 Net loss per share, basic and diluted $ (1.09 ) $ (1.20 ) Year Ended December 31, 2019 2018 Options to purchase common stock 4,215 4,682 Warrants to purchase common stock 26,557 22,302 Series A convertible preferred stock 67 2,022 Unvested restricted stock awards 6,727 3,270 Convertible notes — 988 37,566 33,264
Recent Accounting Pronouncements	Recent Accounting Pronouncements Recently Adopted Accounting Pronouncements In February 2016, the FASB issued Accounting Standards Update (“ASU”) 2016-02, Leases (Topic 842), which changes several aspects of the accounting for leases, including the requirement that all leases with durations greater than twelve months be recognized on the balance sheet. The guidance is effective for annual and interim reporting periods in fiscal years beginning after December 15, 2018. The Company adopted the guidance effective January 1, 2019 and elected the optional transition method to account for the impact of the adoption with a cumulative-effect adjustment in the period of adoption and did not restate prior periods. The Company elected certain practical expedients permitted under the transition guidance. As part of the adoption, the Company recorded a ROU asset and liability upon adoption of the guidance pertaining to its long-term real estate lease for its corporate facilities. No cumulative-effect adjustment was needed. Recently Issued Accounting Pronouncements In January 2017, the FASB issued ASU 2017-04, Intangibles – Goodwill and Other In August 2018, the FASB issued ASU 2018-15, Intangibles—Goodwill and Other—Internal-Use Software (Subtopic 350-40) In November 2019, the FASB issued ASU No. 2019-08, Compensation—Stock Compensation (Topic 718) and Revenue from Contracts with Customers (Topic 606)
SafeOp Convertible Notes
Beneficial Conversion Feature	Beneficial Conversion Feature – SafeOp Convertible Notes In March 2019, the Company’s convertible notes outstanding reached maturity and allowed for the noteholders to elect settlement in cash or shares of the Company’s common stock. As the Convertible Notes provided the holders the benefit to convert to shares of common stock, a BCF with a calculated intrinsic fair value at issuance of $0.2 million existed as of the date the Convertible Notes were able to be converted into shares of the Company’s common stock. Although the holders elected for cash settlement, the BCF was required to be recognized as interest expense on the Company’s consolidated statement of operations and within additional paid-in-capital within the Company’s consolidated statement of stockholders’ equity for the year ended December 31, 2019.
Series B Preferred Stock
Beneficial Conversion Feature	Beneficial Conversion Feature – Series B Preferred Stock In March 2018, the Company completed a private placement of equity securities to certain institutional and accredited investors, providing for the sale by the Company of newly designated Series B Convertible Preferred Stock, which shares of preferred stock were automatically converted into 14.3 million shares of our common stock upon approval by the Company’s stockholders. As the Series B Convertible Preferred Stock provided the holder the benefit to convert to shares of common stock, a beneficial conversion feature (“BCF”) with a calculated intrinsic fair value at issuance of $13.5 million existed as of the date the shares of Series B Convertible Preferred Stock were able to be converted into shares of common stock. This one-time, non-cash deemed dividend impacts net loss attributable to common stockholders and net loss per share on the Company’s consolidated statement of operations for the year ended December 31, 2018

Summary of Significant Accoun_3

Summary of Significant Accounting Policies (Tables)	12 Months Ended
	Dec. 31, 2019
Accounting Policies [Abstract]
Reconciliation of liabilities measured at fair value using significant unobservable inputs	The following table provides a reconciliation of liabilities measured at fair value using significant unobservable inputs (Level 3) for the year ended December 31, 2018 and 2019 (in thousands): Level 3 Liabilities Balance at December 31, 2017 $ — Contingent consideration liability recorded upon acquisition of SafeOp 3,200 Settlement of milestone #1 (1,446 ) Change in fair value measurement 846 Balance at December 31, 2018 2,600 Settlement of milestone #2 (2,889 ) Change in fair value measurement- milestone #2 289 Straight line recognition of liability classified equity award 173 Change in fair value measurement- equity award 93 Balance at December 31, 2019 $ 266
Summary of weighted average assumptions used to compute stock-based compensation costs for stock options granted	The weighted average assumptions used to compute the stock-based compensation costs for the stock options granted during the years ended December 31, 2019 and 2018 are as follows: Year Ended December 31, 2019 2018 Risk-free interest rate 2.00 % 2.85 % Expected dividend yield — — Weighted average expected life (years) 6.09 6.08 Volatility 80.76 % 78.54 %
Summary of compensation cost for stock-based compensation arrangements	The compensation cost that has been included in the Company’s consolidated statements of operations for all stock-based compensation arrangements is detailed as follows (in thousands): Year Ended December 31, 2019 2018 Cost of revenues $ 146 $ 73 Research and development 752 351 Sales, general and administrative 10,058 4,880 Total $ 10,956 $ 5,304
Computation of Basic and Diluted Loss Per Share	The following table sets forth the computation of basic and diluted loss per share (in thousands, except per share data): Year Ended December 31, 2019 2018 Numerator: Net loss, basic and diluted $ (57,002 ) $ (42,463 ) Denominator: Weighted average common shares outstanding 52,520 35,402 Weighted average unvested common shares subject to repurchase (286 ) (87 ) Weighted average common shares outstanding - basic and diluted 52,234 35,315 Net loss per share, basic and diluted $ (1.09 ) $ (1.20 )
Weighted-average anti-dilutive securities not included in diluted net loss per share	The anti-dilutive securities not included in diluted net loss per share were as follows calculated on a weighted average basis (in thousands): Year Ended December 31, 2019 2018 Options to purchase common stock 4,215 4,682 Warrants to purchase common stock 26,557 22,302 Series A convertible preferred stock 67 2,022 Unvested restricted stock awards 6,727 3,270 Convertible notes — 988 37,566 33,264

Balance Sheet Details (Tables)

Balance Sheet Details (Tables)	12 Months Ended
	Dec. 31, 2019
Balance Sheet Related Disclosures [Abstract]
Accounts receivable, net	Accounts receivable consist of the following (in thousands): December 31, 2019 2018 Accounts receivable $ 16,436 $ 15,291 Less allowance for doubtful accounts (286 ) (196 ) Accounts receivable, net $ 16,150 $ 15,095
Inventories, net	Inventories consist of the following (in thousands): December 31, 2019 2018 Raw materials $ 5,822 $ 5,813 Work-in-process 1,578 952 Finished goods 51,669 39,758 59,069 46,523 Less reserve for excess and obsolete (24,215 ) (17,758 ) Inventories, net $ 34,854 $ 28,765
Property and equipment, net	Property and equipment consist of the following (in thousands, except as indicated): Useful lives December 31, (in years) 2019 2018 Surgical instruments 4 $ 58,502 $ 54,848 Machinery and equipment 7 6,038 5,971 Computer equipment 3 3,594 3,104 Office furniture and equipment 5 1,297 1,155 Leasehold improvements various 1,761 1,765 Construction in progress n/a 496 92 71,688 66,935 Less accumulated depreciation and amortization (51,966 ) (53,700 ) Property and equipment, net $ 19,722 $ 13,235
Intangible assets, net	In conjunction with the acquisition of SafeOp in March 2018, the Company recorded $21.6 million of new intangible assets. See Note 8 for further information regarding the acquisition. Intangible assets, net consist of the following (in thousands, except as indicated): Remaining Avg. Useful lives December 31, (in years) 2019 2018 Developed product technology 10 $ 26,976 $ 26,976 Intellectual property — 1,004 1,004 License agreements 1 5,536 5,536 Trademarks and trade names — 792 792 Customer-related 5 7,458 7,458 Distribution network 4 4,027 4,027 In process research and development 19 8,800 8,800 54,593 54,593 Less accumulated amortization (28,988 ) (28,185 ) Intangible assets, net $ 25,605 $ 26,408
Schedule of intangible assets, future expected amortization expense	Future amortization expense related to intangible assets as of December 31, 2019 is as follows (in thousands): Year Ending December 31, 2020 $ 1,869 2021 1,888 2022 1,888 2023 1,888 2024 1,785 Thereafter 16,287 Total $ 25,605
Accrued expenses	Accrued expenses consist of the following (in thousands): December 31, 2019 2018 Commissions and sales milestones $ 5,299 $ 3,594 Payroll and payroll related 7,949 3,222 Litigation settlement obligation 4,400 4,400 Professional fees 3,945 2,637 Royalties 1,981 1,354 Restructuring and severance accruals 29 710 Taxes 82 (3 ) Interest 155 261 Acquisition related - contingent consideration - 2,600 Other 2,576 3,541 Total accrued expenses $ 26,416 $ 22,316
Schedule of Other Long-Term Liabilities	Other long-term liabilities consist of the following (in thousands): December 31, 2019 December 31, 2018 Litigation settlement obligation - long-term portion $ 10,712 $ 13,954 Line of credit exit fee 600 600 Tax liabilities 373 835 Other 266 - Other long-term liabilities $ 11,951 $ 15,389

Debt (Tables)

Debt (Tables)	12 Months Ended
	Dec. 31, 2019
Debt Disclosure [Abstract]
Long-Term Debt	Long-term debt consists of the following (in thousands): December 31, 2019 2018 Amended Credit Facility with MidCap $ 12,785 $ 11,010 Inventory Financing 2,987 — Squadron Term Loan 45,000 35,000 Notes payable 457 296 Convertible note — 3,000 Total 61,229 49,306 Add: capital leases 101 126 Less: debt discount (7,393 ) (3,857 ) Total 53,937 45,575 Less: current portion of long-term debt (489 ) (3,276 ) Total long-term debt, net of current portion $ 53,448 $ 42,299
Principal Payments on Debt	Principal payments on debt are as follows as of December 31, 2019 (in thousands): Year Ending December 31, 2020 $ 458 2021 4,483 2022 20,471 2023 35,817 2024 and thereafter — Total 61,229 Add: capital lease principal payments 101 Less: debt discount (7,393 ) Total 53,937 Less: current portion of long-term debt (489 ) Long-term debt, net of current portion $ 53,448

Commitments and Contingencies (

Commitments and Contingencies (Tables)	12 Months Ended
	Dec. 31, 2019
Commitments And Contingencies Disclosure [Abstract]
Future minimum annual lease payments	Future minimum annual undiscounted lease payments under the Company’s operating and capital leases are as follows (in thousands): Year ending December 31, 2020 $ 1,488 2021 921 2022 42 Total undiscounted lease payments 2,451 Less: present value adjustment (212 ) Operating lease liability 2,239 Less: current portion of operating lease liability (1,314 ) Operating lease liability, less current portion $ 925

Orthotec Settlement (Tables)

Orthotec Settlement (Tables)	12 Months Ended
	Dec. 31, 2019
Commitments And Contingencies Disclosure [Abstract]
Schedule of Reconciliation of Total Net Settlement Obligation	A reconciliation of the total net settlement obligation is as follows (in thousands): December 31, 2019 December 31, 2018 Litigation settlement obligation - short-term portion $ 4,400 $ 4,400 Litigation settlement obligation - long-term portion 10,712 13,954 Total 15,112 18,354 Future Interest 2,121 3,279 Total settlement obligation, gross 17,233 21,633 Related party receivable - included in stockholders' equity (5,000 ) (5,000 ) Total settlement obligation, net $ 12,233 $ 16,633

Equity (Tables)

Equity (Tables)	12 Months Ended
	Dec. 31, 2019
Equity [Abstract]
Summary of Outstanding Warrants	A summary of all outstanding warrants is as follows: Number of Warrants Strike Price 2017 Common Stock Warrants 3,232,000 $ 2.00 2017 Banker Warrants 148,554 $ 2.50 2018 Common Stock Warrants 13,770,488 $ 3.50 Merger Warrants 2,199,682 $ 3.50 Executive 1,327,434 $ 5.00 Squadron Capital 845,000 $ 3.15 Squadron Capital 4,838,710 $ 2.17 Other 195,312 $ 3.85 Total 26,557,180

Stock Benefit Plans and Stock_2

Stock Benefit Plans and Stock-Based Compensation (Tables)	12 Months Ended
	Dec. 31, 2019
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Summary of Stock Option Activity	A summary of the Company’s stock option activity under the Plans and related information is as follows (in thousands, except as indicated and per share data): Shares Weighted average exercise price Weighted average remaining contractual term (in years) Aggregate intrinsic value Outstanding at December 31, 2018 4,723 $ 3.64 Granted 195 $ 4.41 Exercised (161 ) $ 2.75 Forfeited (542 ) $ 7.00 Outstanding at December 31, 2019 4,215 $ 3.27 7.80 $ 17,961 Options vested and exercisable at December 31, 2019 2,238 $ 3.71 7.40 $ 9,438 Options vested and expected to vest at December 31, 2019 4,028 $ 3.29 7.77 $ 17,177
Summary of Information about Restricted Stock Awards, Restricted Stock Units and Performance-Based Restricted Units Activity (Detail)	The following table summarizes information about the restricted stock awards, restricted stock units and performance-based restricted units activity (in thousands, except as indicated and per share data): Shares Weighted average grant date fair value Weighted average remaining recognition period (in years) Unvested at December 31, 2018 3,270 $ 2.94 Awarded 4,802 $ 1.92 Vested (1,224 ) $ 2.83 Forfeited (121 ) $ 3.11 Unvested at December 31, 2019 6,727 $ 2.17 2.32
Summary of Common Stock Reserved for Future Issuance	Common stock reserved for future issuance consists of the following (in thousands): December 31, 2019 Stock options outstanding 4,215 Unvested restricted stock awards 6,727 Employee stock purchase plan 117 Series A convertible preferred stock 67 Warrants outstanding 26,557 Authorized for future grant under the Distributor and Development Services plans 3,908 Authorized for future grant under the Management Objective Strategic Incentive Plan 445 Authorized for future grant under the Plans 1,628 43,664

Income Taxes (Tables)

Income Taxes (Tables)	12 Months Ended
	Dec. 31, 2019
Income Tax Disclosure [Abstract]
Components of Pretax Income (Loss)	The components of the pretax income (loss) are presented in the following table (in thousands): Year Ended December 31, 2019 2018 U.S. Domestic $ (57,141 ) $ (30,169 ) Foreign (100 ) (167 ) Pretax loss from operations $ (57,241 ) $ (30,336 )
Components of (Benefit) Provision for Income Taxes from Continuing Operations	The components of the (benefit) provision for income taxes from continuing operations are presented in the following table (in thousands): Year Ended December 31, 2019 2018 Current income tax (benefit) provision: Federal $ — $ (64 ) State 207 86 Foreign — 4 Total current 207 26 Deferred income tax benefit: Federal (195 ) (1,140 ) State (251 ) (247 ) Total deferred (446 ) (1,387 ) Total income tax benefit $ (239 ) $ (1,361 )
Schedule of Effective Income Tax Rate Reconciliation	The provision for income taxes differs from the amount of income tax determined by applying the applicable U.S. statutory federal income tax rate to pretax income (loss) from continuing operations as a result of the following differences: December 31, 2019 2018 Federal statutory rate 21.00 % 21.00 % Adjustments for tax effects of: State taxes, net 0.12 % 0.47 % Stock-based compensation 0.26 % (4.29 )% R&D credit expiration (5.96 )% — Fair market value adjustments — (0.59 )% Other permanent adjustments (0.42 )% (0.56 )% Foreign partnership liquidation 19.19 % — Federal uncertain tax positions 3.25 % 0.30 % NOL expiration (3.01 )% — Other 1.16 % (1.57 )% Valuation allowance (35.09 )% (10.25 )% Effective income tax rate 0.50 % 4.51 %
Significant Components of Company's Deferred Tax Assets and Liabilities	Significant components of the Company’s deferred tax assets and liabilities as of December 31, 2019 and 2018 are as follows (in thousands): December 31, 2019 2018 Deferred tax assets: Accruals and reserves $ 2,730 $ 1,133 Income tax credit carryforwards 1,591 3,150 Interest 4,095 1,351 Inventory 8,625 4,959 Legal settlement 3,789 4,693 Net operating losses 53,592 45,092 Stock-based compensation 2,256 1,182 Total deferred tax assets 76,678 61,560 Valuation allowance (71,159 ) (46,578 ) Total deferred tax assets, net of valuation allowance 5,519 14,982 Deferred tax liabilities: Property and equipment (3,117 ) (21 ) Goodwill and intangibles (2,344 ) (1,972 ) Investment in foreign partnership — (13,370 ) Total deferred tax liabilities (5,461 ) (15,363 ) Net deferred tax assets (liabilities) $ 58 $ (381 )
Summary of Changes to Unrecognized Tax Benefits	The following table summarizes the changes to unrecognized tax benefits (in thousands): Year ended December 31, 2019 2018 Unrecognized tax benefit at the beginning of the year $ 4,334 $ 4,440 Reductions as a result of lapse of applicable statute of limitations (1,882 ) (106 ) Unrecognized tax benefits at the end of the year $ 2,452 $ 4,334

Restructuring Activities (Table

Restructuring Activities (Tables)	12 Months Ended
	Dec. 31, 2019
Restructuring And Related Activities [Abstract]
Rollforward of accrued restructuring liability	A rollforward of the accrued restructuring liability is presented below (in thousands): Balance at December 31, 2018 $ 710 Accrued restructuring charges 60 Payments (746 ) Balance at December 31, 2019 $ 24

The Company and Basis of Pres_2

The Company and Basis of Presentation - Additional Information (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2019USD ($)segment	Dec. 31, 2018USD ($)
Company And Basis Of Presentation [Line Items]
Number of reportable segments | segment	1
Working capital	$ 71,900
Cash	47,113	$ 29,054
Stock-based compensation	10,956	5,304
Reclassification
Company And Basis Of Presentation [Line Items]
Stock-based compensation		$ 100
Current Lenders
Company And Basis Of Presentation [Line Items]
Minimum financial covenant cash balance	5,000
Term Loan | Squadron Credit Agreement
Company And Basis Of Presentation [Line Items]
Available additional debt	$ 20,000

Summary of Significant Accoun_4

Summary of Significant Accounting Policies - Additional Information (Details)	Mar. 08, 2018shares	Mar. 31, 2019USD ($)	Mar. 31, 2019USD ($)shares	Sep. 30, 2018shares	Jun. 30, 2018shares	Mar. 31, 2018USD ($)shares	Dec. 31, 2019USD ($)customershares	Dec. 31, 2018USD ($)customershares	Sep. 30, 2019USD ($)
Significant Accounting Policies [Line Items]
Accounts receivable payment terms							30 days
Accounts receivable related to products and services							$ 16,150,000	$ 15,095,000
Operating lease, ROU asset		$ 2,400,000	$ 2,400,000				1,860,000
Operating lease liability		2,900,000	$ 2,900,000				2,239,000
Removal of deferred rent									$ 600,000
Goodwill and intangible asset impairment charge							0
Impairment charges of Long-lived assets disposition							0	0
Impairment charges of Long-lived assets held for use							0	0
Sales, general and administrative							101,714,000	72,640,000
Preferred stock convertible to common stock | shares						14,300,000
Recognition of beneficial conversion feature series B preferred stock						$ 13,500,000		13,488,000
Recognition of beneficial conversion feature SafeOp convertible notes		$ 200,000
Product Shipment
Significant Accounting Policies [Line Items]
Sales, general and administrative							$ 4,000,000	$ 2,500,000
SafeOp Surgical, Inc.
Significant Accounting Policies [Line Items]
Preferred stock convertible to common stock | shares	987,578
SafeOp Surgical, Inc. | Common Stock
Significant Accounting Policies [Line Items]
Stock issued for acquisition | shares	2,975,209		886,843	174,302	115,621		886,843	443,421
Fair value, inputs, level 3
Significant Accounting Policies [Line Items]
Vesting period							4 years
Fair value of the cash settled award							$ 1,700
Minimum
Significant Accounting Policies [Line Items]
Estimated useful lives of property and equipment							3 years
Minimum | Acquired Technology, Customer Relationships, Manufacturing Know-how, Licensed Technology, Supply Agreements and Certain Trade Names and Trademarks
Significant Accounting Policies [Line Items]
Intangible assets, amortization period							1 year
Maximum
Significant Accounting Policies [Line Items]
Estimated useful lives of property and equipment							7 years
Maximum | Acquired Technology, Customer Relationships, Manufacturing Know-how, Licensed Technology, Supply Agreements and Certain Trade Names and Trademarks
Significant Accounting Policies [Line Items]
Intangible assets, amortization period							20 years
Sales | Customer Concentration Risk
Significant Accounting Policies [Line Items]
Concentration risk, number of customers | customer							0	0
Accounts Receivable | Customer Concentration Risk
Significant Accounting Policies [Line Items]
Concentration risk, number of customers | customer							0	0

Summary of Significant Accoun_5

Summary of Significant Accounting Policies - Reconciliation of Liabilities (Details) - Fair value, inputs, level 3 - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Roll Forward]
Beginning balance	$ 2,600
Settlement of milestone #1 and #2	(2,889)	$ (1,446)
Change in fair value measurement and milestone #2	289
Straight line recognition of liability classified equity award	173
Change in fair value measurement- equity award	93
Change in fair value measurement		846
Ending balance	$ 266	2,600
SafeOp Surgical, Inc.
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Roll Forward]
Contingent consideration liability recorded upon acquisition of SafeOp		$ 3,200

Summary of Significant Accoun_6

Summary of Significant Accounting Policies - Summary of Weighted Average Assumptions Used to Compute Stock-Based Compensation Costs for Stock Options Granted (Detail) - Options to purchase common stock	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Risk-free interest rate	2.00%	2.85%
Expected dividend yield		0.00%
Weighted average expected life	6 years 1 month 2 days	6 years 29 days
Volatility	80.76%	78.54%

Summary of Significant Accoun_7

Summary of Significant Accounting Policies - Summary of Compensation Cost for Stock-Based Compensation Arrangements (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation expense	$ 10,956	$ 5,304
Cost of revenues
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation expense	146	73
Research and development
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation expense	752	351
Sales, General and Administrative
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation expense	$ 10,058	$ 4,880

Summary of Significant Accoun_8

Summary of Significant Accounting Policies - Computation of Basic and Diluted Loss Per Share (Detail) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Numerator:
Net loss, basic and diluted	$ (57,002)	$ (42,463)
Denominator:
Weighted average common shares outstanding	52,520	35,402
Weighted average unvested common shares subject to repurchase	(286)	(87)
Weighted average common shares outstanding - basic and diluted	52,234	35,315
Net loss per share, basic and diluted	$ (1.09)	$ (1.20)

Summary of Significant Accoun_9

Summary of Significant Accounting Policies - Weighted-Average Anti-Dilutive Securities Not Included in Diluted Net Loss Per Share (Details) - shares shares in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Anti-dilutive securities not included in diluted net loss per share (in shares)	37,566	33,264
Convertible notes
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Anti-dilutive securities not included in diluted net loss per share (in shares)		988
Series A Convertible Preferred Stock
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Anti-dilutive securities not included in diluted net loss per share (in shares)	67	2,022
Options to purchase common stock
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Anti-dilutive securities not included in diluted net loss per share (in shares)	4,215	4,682
Warrants to purchase common stock
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Anti-dilutive securities not included in diluted net loss per share (in shares)	26,557	22,302
Unvested restricted stock awards
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Anti-dilutive securities not included in diluted net loss per share (in shares)	6,727	3,270

Balance Sheet Details - Account

Balance Sheet Details - Accounts Receivable, Net (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Balance Sheet Related Disclosures [Abstract]
Accounts receivable	$ 16,436	$ 15,291
Less allowance for doubtful accounts	(286)	(196)
Accounts receivable, net	$ 16,150	$ 15,095

Balance Sheet Details - Invento

Balance Sheet Details - Inventories, Net (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Balance Sheet Related Disclosures [Abstract]
Raw materials	$ 5,822	$ 5,813
Work-in-process	1,578	952
Finished goods	51,669	39,758
Inventory, gross, total	59,069	46,523
Less reserve for excess and obsolete	(24,215)	(17,758)
Inventories, net	$ 34,854	$ 28,765

Balance Sheet Details - Propert

Balance Sheet Details - Property and Equipment, Net (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Property, Plant and Equipment [Line Items]
Property and equipment, gross	$ 71,688	$ 66,935
Less accumulated depreciation and amortization	(51,966)	(53,700)
Property and equipment, net	$ 19,722	13,235
Surgical instruments
Property, Plant and Equipment [Line Items]
Useful lives	4 years
Property and equipment, gross	$ 58,502	54,848
Machinery and equipment
Property, Plant and Equipment [Line Items]
Useful lives	7 years
Property and equipment, gross	$ 6,038	5,971
Computer equipment
Property, Plant and Equipment [Line Items]
Useful lives	3 years
Property and equipment, gross	$ 3,594	3,104
Office furniture and equipment
Property, Plant and Equipment [Line Items]
Useful lives	5 years
Property and equipment, gross	$ 1,297	1,155
Leasehold improvements
Property, Plant and Equipment [Line Items]
Various useful lives of leasehold improvements	various
Property and equipment, gross	$ 1,761	1,765
Construction in progress
Property, Plant and Equipment [Line Items]
Property and equipment, gross	$ 496	$ 92

Balance Sheet Details - Intangi

Balance Sheet Details - Intangible Assets - Additional Information (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Mar. 31, 2018
Property, Plant and Equipment [Line Items]
Depreciation	$ 6.8	$ 6
Amortization of intangible assets	0.7	0.8
SafeOp Surgical, Inc.
Property, Plant and Equipment [Line Items]
Business acquisition, intangible assets recorded			$ 21.6
Machinery and equipment
Property, Plant and Equipment [Line Items]
Capital leased assets, gross	$ 0.1	$ 0.1

Balance Sheet Details - Intan_2

Balance Sheet Details - Intangible Assets (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Finite Lived Intangible Assets [Line Items]
Intangible assets, Gross	$ 54,593	$ 54,593
Less accumulated amortization	(28,988)	(28,185)
Intangible assets, net	$ 25,605	26,408
Developed product technology
Finite Lived Intangible Assets [Line Items]
Useful lives	10 years
Intangible assets, Gross	$ 26,976	26,976
Intellectual property
Finite Lived Intangible Assets [Line Items]
Intangible assets, Gross	$ 1,004	1,004
License agreements
Finite Lived Intangible Assets [Line Items]
Useful lives	1 year
Intangible assets, Gross	$ 5,536	5,536
Trademarks and trade names
Finite Lived Intangible Assets [Line Items]
Intangible assets, Gross	$ 792	792
Customer-related
Finite Lived Intangible Assets [Line Items]
Useful lives	5 years
Intangible assets, Gross	$ 7,458	7,458
Distribution network
Finite Lived Intangible Assets [Line Items]
Useful lives	4 years
Intangible assets, Gross	$ 4,027	4,027
In process research and development
Finite Lived Intangible Assets [Line Items]
Useful lives	19 years
Intangible assets, Gross	$ 8,800	$ 8,800

Balance Sheet Details - Schedul

Balance Sheet Details - Schedule of Intangible Assets, Future Expected Amortization Expense (Details) $ in Thousands	Dec. 31, 2019USD ($)
Balance Sheet Related Disclosures [Abstract]
2020	$ 1,869
2021	1,888
2022	1,888
2023	1,888
2024	1,785
Thereafter	16,287
Total	$ 25,605

Balance Sheet Details - Accrued

Balance Sheet Details - Accrued Expenses (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Balance Sheet Related Disclosures [Abstract]
Commissions and sales milestones	$ 5,299	$ 3,594
Payroll and payroll related	7,949	3,222
Litigation settlement obligation	4,400	4,400
Professional fees	3,945	2,637
Royalties	1,981	1,354
Restructuring and severance accruals	29	710
Taxes	82	(3)
Interest	155	261
Acquisition related - contingent consideration		2,600
Other	2,576	3,541
Total accrued expenses	$ 26,416	$ 22,316

Balance Sheet Details - Sched_2

Balance Sheet Details - Schedule of Other Long-Term Liabilities (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Balance Sheet Related Disclosures [Abstract]
Litigation settlement obligation - long-term portion	$ 10,712	$ 13,954
Line of credit exit fee	600	600
Tax liabilities	373	835
Other	266
Other long-term liabilities	$ 11,951	$ 15,389

Discontinued Operations - Addit

Discontinued Operations - Additional Information (Details) $ in Thousands	Sep. 01, 2016option	Mar. 31, 2019	Dec. 31, 2019USD ($)	Dec. 31, 2018USD ($)
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Contracts revenue			$ 113,427	$ 91,694
Cost of revenues			35,833	28,457
Supply agreement
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Contracts revenue			5,200	8,000
Cost of revenues			$ 4,800	$ 7,500
Discontinued operations, disposed of by sale | International Operations
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Supply commitment term	3 years
Supply agreement, number of annual options to extend | option	2
Supply agreement, extended term		12 months
Supply agreement, extended period		2020-08

Debt - MidCap Facility Agreemen

Debt - MidCap Facility Agreement (Details) - USD ($)	Nov. 06, 2018	Mar. 08, 2018	Dec. 31, 2019	Dec. 31, 2018
Line of Credit Facility [Line Items]
Unamortized debt discount			$ 7,393,000	$ 3,857,000
Amended credit facility with MidCap
Line of Credit Facility [Line Items]
Unamortized debt discount			$ 900,000
Minimum liquidity covenant amount		$ 5,000,000
Latest effective date of minimum liquidity covenant	2020-03	2019-03
Amended credit facility with MidCap | Maximum
Line of Credit Facility [Line Items]
Effective date of financial covenants of amended credit facility	2020-04	2019-04
Amended credit facility with MidCap | Minimum
Line of Credit Facility [Line Items]
Effective date of financial covenants of amended credit facility	2019-04	2018-04
Amended credit facility with MidCap | Line of Credit | Maximum
Line of Credit Facility [Line Items]
Debt default, interest rate increase			5.00%
Amended credit facility with MidCap | Revolving credit facility
Line of Credit Facility [Line Items]
Maximum borrowing capacity			$ 22,500,000
Line of credit			$ 12,800,000
Line of credit, expiration month and year			2022-12
Interest rate			7.69%
Amended credit facility with MidCap | Revolving credit facility | LIBOR
Line of Credit Facility [Line Items]
Interest rate description			("LIBOR") plus 6.0%
Basis spread			6.00%
Amended credit facility with MidCap | Term Loan
Line of Credit Facility [Line Items]
Maximum borrowing capacity			$ 5,000,000

Debt - Globus Facility Agreemen

Debt - Globus Facility Agreement (Details) - USD ($)	Nov. 07, 2018	Dec. 31, 2019	Dec. 31, 2018	Sep. 01, 2016
Debt Instrument [Line Items]
Final settlement under agreement	$ 29,200,000	$ 112,934,000	$ 89,993,000
Globus facility agreement
Debt Instrument [Line Items]
Maximum borrowing capacity				$ 30,000,000

Debt - Squadron Credit Agreemen

Debt - Squadron Credit Agreement (Details) - USD ($)	Mar. 27, 2019	Nov. 06, 2018	Mar. 31, 2019	Dec. 31, 2019	Dec. 31, 2018	Sep. 01, 2016
Squadron Credit Agreement
Line of Credit Facility [Line Items]
Current interest rate		10.00%
Debt instrument, aggregate principal to be paid on installments		$ 10,000,000
Debt instrument, frequency of periodic payment	29 equal monthly installments	29 equal monthly installments
Debt instrument payment at maturity		$ 25,000,000
Debt instrument, maturity date	Nov. 30, 2023	Nov. 30, 2023
New debt issuance costs			$ 300,000
Additional warrants for future				0
Debt carrying amount, net of issuance cost		$ 38,600,000
Debt issuance cost, amortization period		5 years
Squadron Credit Agreement | Expanded Credit Facility
Line of Credit Facility [Line Items]
Maximum borrowing capacity	$ 30,000,000			$ 45,000,000
Squadron Credit Agreement | Common Stock
Line of Credit Facility [Line Items]
Number of warrants issued (in shares)	4,838,710	845,000
Exercise price of warrants	$ 2.17	$ 3.15
Warrants term	7 years	7 years
Squadron Credit Agreement | Maximum
Line of Credit Facility [Line Items]
Current interest rate		13.00%
Squadron Credit Agreement | Minimum [Member]
Line of Credit Facility [Line Items]
Current interest rate		10.00%
Globus facility agreement
Line of Credit Facility [Line Items]
Maximum borrowing capacity						$ 30,000,000
Term Loan | Squadron Credit Agreement
Line of Credit Facility [Line Items]
Secured debt agreement		$ 35,000,000		45,000,000	$ 35,000,000
Proceeds from secured term loan		34,100,000
Line of Credit | Squadron Credit Agreement
Line of Credit Facility [Line Items]
Line of credit				$ 10,000,000
Minimum liquidity covenant amount		$ 5,000,000
Fixed Charge Coverage Ratio		100.00%
Floor on interest rate	10.00%
Ceiling on interest rate	13.00%
Line of Credit | Squadron Credit Agreement | Maximum
Line of Credit Facility [Line Items]
Debt default, interest rate increase		5.00%
Line of Credit | Squadron Credit Agreement | LIBOR
Line of Credit Facility [Line Items]
Maturity Term		5 years
Interest rate description		LIBOR plus 8%
Line of Credit | Globus facility agreement
Line of Credit Facility [Line Items]
Line of credit		$ 29,200,000

Debt - Inventory Financing Agre

Debt - Inventory Financing Agreement (Details) - Inventory Financing Agreement	12 Months Ended
	Dec. 31, 2019USD ($)
Line of Credit Facility [Line Items]
Maximum borrowing capacity	$ 3,000,000
Line of Credit
Line of Credit Facility [Line Items]
Debt instrument, maturity date	Nov. 6, 2023
Debt instrument, frequency of periodic payment	monthly
Obligation outstanding under inventory financing agreement	$ 3,000,000
LIBOR | Line of Credit
Line of Credit Facility [Line Items]
Interest rate description	LIBOR plus 8%
Basis spread	8.00%
Floor on interest rate	10.00%
Ceiling on interest rate	13.00%

Debt - Other Debt Agreements (D

Debt - Other Debt Agreements (Details)	12 Months Ended
	Dec. 31, 2019Agreement
Debt Disclosure [Abstract]
Capital leases interest percentage	6.40%
Number of capital lease agreement	1

Debt - Long-Term Debt (Detail)

Debt - Long-Term Debt (Detail) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018	Nov. 06, 2018
Debt Instrument [Line Items]
Inventory Financing	$ 2,987
Notes payable	457	$ 296
Convertible note		3,000
Total	61,229	49,306
Add: capital leases	101	126
Less: debt discount	(7,393)	(3,857)
Total	53,937	45,575
Less: current portion of long-term debt	(489)	(3,276)
Total long-term debt, net of current portion	53,448	42,299
Term Loan | Squadron Credit Agreement
Debt Instrument [Line Items]
Squadron Term Loan	45,000	35,000	$ 35,000
Amended Credit Facility And Term Loan With Mid Cap
Debt Instrument [Line Items]
Maximum borrowing capacity	$ 12,785	$ 11,010

Debt - Principal Payments on De

Debt - Principal Payments on Debt (Detail) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Debt Disclosure [Abstract]
2020	$ 458
2021	4,483
2022	20,471
2023	35,817
Total	61,229
Add: capital lease principal payments	101	$ 126
Less: debt discount	(7,393)	(3,857)
Total	53,937	45,575
Less: current portion of long-term debt	(489)	(3,276)
Long-term debt, net of current portion	$ 53,448	$ 42,299

Commitments and Contingencies -

Commitments and Contingencies - Additional Information (Details)	Dec. 04, 2019USD ($)ft²	Dec. 31, 2019USD ($)	Dec. 31, 2018USD ($)ft²	Jan. 01, 2019
Loss Contingencies [Line Items]
Lease interest rate		6.40%
Capital lease commitment outstanding		$ 100,000	$ 100,000
Remaining operating lease term		1 year 8 months 12 days
Rent expense		$ 1,300,000	1,400,000
Cash payments related to operating lease		1,400,000	$ 1,400,000
Liability in connection with lawsuit		0
Alphatec Spine, Inc.
Loss Contingencies [Line Items]
Guaranteed obligated minimum royalty payments through 2022 and beyond		$ 5,400,000
Maximum
Loss Contingencies [Line Items]
Operating lease term		5 years 6 months
Minimum
Loss Contingencies [Line Items]
Operating lease term		1 year
Building lease
Loss Contingencies [Line Items]
Area for facility of office, engineering and research and development space | ft²	121,541		76,000
Lease agreement expiry date	Nov. 30, 2030		Jul. 31, 2021
Lease agreement commencement date	Nov. 15, 2020
Lease renewal term	260 months
Annual increase in base rent	3.00%
Operating lease discount rate				10.50%
First year | Building lease
Loss Contingencies [Line Items]
Lease rent payable per month			$ 111,000
Each year thereafter | Building lease
Loss Contingencies [Line Items]
Lease rent payable increase per month			$ 3,000
First year | Building lease
Loss Contingencies [Line Items]
Lease base rent payment per month	$ 195,000
First year | Building lease | Maximum
Loss Contingencies [Line Items]
Abatement period	10 years
First year | Building lease | Minimum
Loss Contingencies [Line Items]
Abatement period	2 years
Second year | Building lease
Loss Contingencies [Line Items]
Lease base rent payment per month	$ 244,115

Commitments and Contingencies_2

Commitments and Contingencies - Future Minimum Annual Lease Payments (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Mar. 31, 2019
Commitments And Contingencies Disclosure [Abstract]
2020	$ 1,488
2021	921
2022	42
Total undiscounted lease payments	2,451
Less: present value adjustment	(212)
Operating lease liability	2,239	$ 2,900
Less: current portion of operating lease liability	(1,314)
Operating lease liability, less current portion	$ 925

Orthotec Settlement - Additiona

Orthotec Settlement - Additional Information (Details)	Jul. 01, 2016USD ($)	Oct. 01, 2014USD ($)	Aug. 13, 2014USD ($)installment	Sep. 30, 2014USD ($)	Apr. 30, 2014USD ($)	Mar. 31, 2014USD ($)	Dec. 31, 2019USD ($)	Dec. 31, 2018USD ($)
Loss Contingencies [Line Items]
Settlement amount to be contributed							$ 5,000,000	$ 5,000,000
Litigation settlement, remaining outstanding balance including interest							0
Orthotec LLC, litigation settlement
Loss Contingencies [Line Items]
Judgment assessed by court for (against) company			$ 49,000,000
Payments of settlement					$ 15,750,000	$ 1,750,000	40,600,000
Number of quarterly installments | installment			28
Litigation settlement interest, quarterly installments, amount			$ 1,100,000
Litigation settlement, final installment amount			700,000
Litigation settlement, remaining outstanding balance including interest							17,200,000
Orthotec LLC, litigation settlement | HealthpointCapital, LLC
Loss Contingencies [Line Items]
Judgment assessed by court for (against) company				$ 5,000,000
Payments of settlement	$ 1,000,000						1,100,000
Settlement amount to be contributed							$ 5,000,000	$ 5,000,000
Beginning fourth quarter of 2014 | Orthotec LLC, litigation settlement
Loss Contingencies [Line Items]
Settlement amount, remaining balance		$ 31,500,000
Litigation settlement interest, quarterly installments, amount			$ 1,100,000
Litigation settlement interest rate			7.00%
Litigation settlement payments, quarterly payment amount			$ 1,100,000
Final installment | Orthotec LLC, litigation settlement
Loss Contingencies [Line Items]
Number of quarterly installments | installment			1

Orthotec Settlement - Schedule

Orthotec Settlement - Schedule of Reconciliation of Total Net Settlement Obligation (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Commitments And Contingencies Disclosure [Abstract]
Litigation settlement obligation - short-term portion	$ 4,400	$ 4,400
Litigation settlement obligation - long-term portion	10,712	13,954
Total	15,112	18,354
Future Interest	2,121	3,279
Total settlement obligation, gross	17,233	21,633
Related party receivable - included in stockholders' equity	(5,000)	(5,000)
Total settlement obligation, net	$ 12,233	$ 16,633

Acquisition of SafeOp Surgica_2

Acquisition of SafeOp Surgical, Inc. - Additional Information (Details) - USD ($) $ / shares in Units, $ in Thousands	Mar. 08, 2018	Mar. 31, 2019	Mar. 31, 2019	Sep. 30, 2018	Jun. 30, 2018	Dec. 31, 2019	Dec. 31, 2018	Mar. 31, 2018
Business Acquisition [Line Items]
Convertible note convertible to common stock								14,300,000
Recognition of beneficial conversion feature SafeOp convertible notes		$ 200
Accretion to contingent consideration						$ 289	$ 846
SafeOp Surgical, Inc.
Business Acquisition [Line Items]
Business acquisition date	Mar. 8, 2018
Cash paid	$ 15,100						$ 15,100
Stock issued for acquisition, value	$ 9,800
Closing share price	$ 3.30
Convertible notes issued	$ 3,000
Convertible note convertible to common stock	987,578
Number of warrants issued	2,200,000
Exercise price of warrants per share	$ 3.50
Convertible note, maturity date	Mar. 9, 2019
Warrant issued to purchase of common stock and purchase of common stock period	5 years
Accretion to contingent consideration						$ 300
SafeOp Surgical, Inc. | Interest Expense
Business Acquisition [Line Items]
Recognition of beneficial conversion feature SafeOp convertible notes	$ 200
SafeOp Surgical, Inc. | Common Stock
Business Acquisition [Line Items]
Number of shares of common stock issued	3,265,132
Stock issued for acquisition	2,975,209		886,843	174,302	115,621	886,843	443,421

Equity - Additional Information

Equity - Additional Information (Detail) - USD ($) $ / shares in Units, $ in Thousands	Aug. 02, 2019	Mar. 08, 2018	Dec. 31, 2011	Mar. 31, 2017	Dec. 31, 2019	Dec. 31, 2018	Jun. 30, 2019	Mar. 31, 2018
Subsidiary Sale Of Stock [Line Items]
Net proceeds from offering					$ 1,977	$ 51,902
Redeemable preferred stock carrying value					$ 23,603	$ 23,603
Redeemable preferred stock authorized					20,000,000	20,000,000
Redeemable preferred stock, price per share					$ 0.0001	$ 0.0001
Preferred stock convertible to common stock								14,300,000
Warrant outstanding					26,557,180
Stock-based compensation					$ 10,956	$ 5,304
Patrick S. Miles
Subsidiary Sale Of Stock [Line Items]
Number of warrants issued (in shares)						1,327,434
Exercise price of warrants						$ 5
Warrant expiration period						5 years
Stock-based compensation						$ 1,400
SiliconValley Bank (SVB)
Subsidiary Sale Of Stock [Line Items]
Number of warrants issued (in shares)			7,812
Exercise price of warrants			$ 19.20
Amendment fee amount waived			$ 200
Warrant term			10 years
Squadron Capital
Subsidiary Sale Of Stock [Line Items]
Number of warrants issued (in shares)						845,000	4,838,710
Exercise price of warrants						$ 3.15	$ 2.17
Warrant outstanding							5,683,710
Warrant expiration period						7 years
2017 Common Stock Warrants
Subsidiary Sale Of Stock [Line Items]
Exercise price of warrants					$ 2
Warrant outstanding					3,232,000
Proceeds from exercise of warrant					$ 1,100	$ 4,000
Number of warrants exercised					500,000	1,900,000
2017 Common Stock Warrants | Maximum
Subsidiary Sale Of Stock [Line Items]
Beneficial ownership limitation percentage					4.99%
Beneficial ownership, limitation option, percentage					9.99%
Beneficial ownership limitation notification period					61 days
2017 Banker Warrants
Subsidiary Sale Of Stock [Line Items]
Exercise price of warrants					$ 2.50
Warrant outstanding					148,554
2018 Common Stock Warrants
Subsidiary Sale Of Stock [Line Items]
Number of warrants issued (in shares)					1,800,000
Exercise price of warrants					$ 3.50
Warrant outstanding					13,770,488
Warrant expiration period					5 years
2018 Common Stock Warrants | Maximum
Subsidiary Sale Of Stock [Line Items]
Beneficial ownership limitation percentage					4.99%
Beneficial ownership, limitation option, percentage					9.99%
Beneficial ownership limitation notification period					61 days
Redeemable Preferred Stock
Subsidiary Sale Of Stock [Line Items]
Redeemable preferred stock carrying value					$ 23,600	$ 23,600
Redeemable preferred stock authorized					20,000,000	20,000,000
Redeemable preferred stock redemption, price per share					$ 9	$ 9
Redeemable preferred stock, price per share					$ 7.11	$ 7.11
Series A Convertible Preferred Stock
Subsidiary Sale Of Stock [Line Items]
Number of preferred shares converted					3,909	1,274
Number of preferred shares outstanding for being conversion					135
Common Stock
Subsidiary Sale Of Stock [Line Items]
Common stock issued					12,535,000
Number of preferred shares converted to common stock					1,954,000	14,986,000
Common Stock | Series A Convertible Preferred Stock
Subsidiary Sale Of Stock [Line Items]
Number of preferred shares converted to common stock					1,954,334	636,997
Number of preferred shares outstanding for being conversion to common stock					67,338
August 2019 Offering
Subsidiary Sale Of Stock [Line Items]
Net proceeds from offering	$ 53,900
August 2019 Offering | Common Stock
Subsidiary Sale Of Stock [Line Items]
Common stock issued	12,535,000
Shares issued price per share	$ 4.60
Shares issued of underwriters option to purchase additional shares	1,635,000
2017 Private Placement | 2017 Common Stock Warrants
Subsidiary Sale Of Stock [Line Items]
Exercise price of warrants					$ 2
2017 Private Placement | 2017 Banker Warrants
Subsidiary Sale Of Stock [Line Items]
Exercise price of warrants					$ 2.50
2017 Private Placement | 2017 Banker Warrants | Maximum
Subsidiary Sale Of Stock [Line Items]
Number of warrants issued (in shares)					471,600
2017 Private Placement | Series A Convertible Preferred Stock
Subsidiary Sale Of Stock [Line Items]
Shares issued price per share				$ 1,000
Preferred stock, shares issued				15,245
2017 Private Placement | Common Stock
Subsidiary Sale Of Stock [Line Items]
Issuance of common stock upon securities purchase agreement				1,809,628
Common stock purchase price per share				$ 2
2017 Private Placement | Common Stock | 2017 Common Stock Warrants | Maximum
Subsidiary Sale Of Stock [Line Items]
Number of warrants issued (in shares)					9,432,000
2017 Private Placement | Common Stock | Series A Convertible Preferred Stock
Subsidiary Sale Of Stock [Line Items]
Preferred stock convertible to common stock				7,622,372
2018 Private Placement
Subsidiary Sale Of Stock [Line Items]
Exercise price of warrants		$ 3.50
Warrant expiration period		5 years
Aggregate gross proceeds for private placement		$ 45,200
2018 Private Placement | 2017 Common Stock Warrants
Subsidiary Sale Of Stock [Line Items]
Exercise price of warrants		$ 2
Warrant outstanding		2,400,000
Proceeds from exercise of warrant						$ 4,800
2018 Private Placement | 2017 Banker Warrants
Subsidiary Sale Of Stock [Line Items]
Warrant outstanding					148,554
Proceeds from exercise of warrant					$ 100	$ 800
Number of warrants exercised					18,864	304,182
2018 Private Placement | 2018 Common Stock Warrants
Subsidiary Sale Of Stock [Line Items]
Warrant outstanding					13,770,488
Proceeds from exercise of warrant					$ 600
Number of warrants exercised					200,000	0
2018 Private Placement | Series A Convertible Preferred Stock
Subsidiary Sale Of Stock [Line Items]
Shares issued price per share		$ 1,000
Preferred stock, shares issued		45,200
2018 Private Placement | Common Stock | Maximum
Subsidiary Sale Of Stock [Line Items]
Number of warrants issued (in shares)		12,196,851
2018 Private Placement | Common Stock | Series A Convertible Preferred Stock
Subsidiary Sale Of Stock [Line Items]
Preferred stock convertible to common stock		14,349,236

Equity - Summary of Outstanding

Equity - Summary of Outstanding Warrants (Details)	Dec. 31, 2019$ / sharesshares
Class Of Warrant Or Right [Line Items]
Number of Warrants	26,557,180
2017 Common Stock Warrants
Class Of Warrant Or Right [Line Items]
Number of Warrants	3,232,000
Exercise price of warrants per share | $ / shares	$ 2
2017 Banker Warrants
Class Of Warrant Or Right [Line Items]
Number of Warrants	148,554
Exercise price of warrants per share | $ / shares	$ 2.50
2018 Common Stock Warrants
Class Of Warrant Or Right [Line Items]
Number of Warrants	13,770,488
Exercise price of warrants per share | $ / shares	$ 3.50
Merger Warrants
Class Of Warrant Or Right [Line Items]
Number of Warrants	2,199,682
Exercise price of warrants per share | $ / shares	$ 3.50
Executive Warrants
Class Of Warrant Or Right [Line Items]
Number of Warrants	1,327,434
Exercise price of warrants per share | $ / shares	$ 5
Squadron Capital Warrant Exercise Price at $3.15
Class Of Warrant Or Right [Line Items]
Number of Warrants	845,000
Exercise price of warrants per share | $ / shares	$ 3.15
Squadron Capital Warrant Exercise Price at $2.17
Class Of Warrant Or Right [Line Items]
Number of Warrants	4,838,710
Exercise price of warrants per share | $ / shares	$ 2.17
Other Warrants
Class Of Warrant Or Right [Line Items]
Number of Warrants	195,312
Exercise price of warrants per share | $ / shares	$ 3.85

Stock Benefit Plans and Stock_3

Stock Benefit Plans and Stock-Based Compensation - Additional Information (Details) - USD ($)	1 Months Ended		3 Months Ended	12 Months Ended
	Jul. 31, 2019	Feb. 28, 2018	Sep. 30, 2016	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Common stock reserved for future issuance				43,664,000
Stock-based compensation				$ 10,956,000	$ 5,304,000
Collaborative Arrangement | Elite Medical Holdings L L C And Pac3 Surgical Products L L C
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Payments of settlement		$ 400,000
Gain Loss On Contract Termination					$ 6,200,000
Common Stock
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Common stock issued				12,535,000
Employee Stock Option
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Common stock reserved for future issuance				4,215,000
Weighted-average grant-date fair value of stock options granted				$ 1.92	$ 2
Share price				$ 7.10
Unrecognized compensation expense for stock options and awards expected to be recognized				$ 3,700,000
Straight-line basis over a weighted average period				2 years 3 months 18 days
Restricted Stock
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Common stock reserved for future issuance				6,727,000
Restricted shares granted under the plan				4,802,000
Straight-line basis over a weighted average period				2 years 3 months 25 days
Weighted average fair value of awards granted				$ 1.92	$ 2.87
Unrecognized compensation expense for restricted stock and awards expected to be recognized				$ 16,000,000
2016 Equity Incentive Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Common stock reserved for future issuance			1,083,333
Number of shares available for grant				666,742
2016 Equity Incentive Plan | Employee Stock Option
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expiration period			10 years
Award vesting period			4 years
Exercise price minimum percentage of market price on grant date			100.00%
2016 Equity Incentive Plan | Employee Stock Option | 10 Percent Stockholder
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expiration period			5 years
Exercise price minimum percentage of market price on grant date			110.00%
Inducement Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Common stock reserved for future issuance				801,099
Maximum award to be deductible other than options				$ 1,000,000
2019 Management Objective Strategic Incentive Plan | Board of Directors Chairman | Common Stock
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share authorized grant of warrants	500,000
Maximum grant of shares per participant	50,000
2019 Management Objective Strategic Incentive Plan | Restricted Stock
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Restricted shares granted under the plan				55,000
Two Thousand Seventeen Distributor Inducement Plan | Common Stock
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of warrants issued (in shares)				300,000
Common stock issued				92,000
Stock-based compensation				$ 400,000	$ 200,000
Number of warrants available to be granted						50,000
Two Thousand Seventeen Distributor Inducement Plan | Board of Directors Chairman | Common Stock
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share authorized grant of warrants						1,000,000
Two Thousand Seventeen Distributor Inducement Plan | Restricted Stock Units | Common Stock
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares available for grant						75,000
2017 Development Services Plan | Board of Directors Chairman | Common Stock
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share authorized grant of warrants				2,400,000	3,000,000
Common stock issued				0
Issuance of shares granted to distributors was vested				0

Stock Benefit Plans and Stock_4

Stock Benefit Plans and Stock-Based Compensation - Summary of Stock Option Activity (Detail) $ / shares in Units, shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2019USD ($)$ / sharesshares
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding [Roll Forward]
Shares Outstanding, Beginning balance | shares	4,723
Shares, Granted | shares	195
Shares, Exercised | shares	(161)
Shares, Forfeited | shares	(542)
Shares Outstanding, Ending balance | shares	4,215
Shares, Options vested and exercisable | shares	2,238
Shares, Options vested and expected to vest | shares	4,028
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Exercise Price [Abstract]
Weighted average exercise price, Outstanding, Beginning balance | $ / shares	$ 3.64
Weighted average exercise price, Granted | $ / shares	4.41
Weighted average exercise price,Exercised | $ / shares	2.75
Weighted average exercise price, Forfeited | $ / shares	7
Weighted average exercise price, Outstanding, Ending balance | $ / shares	3.27
Weighted average exercise price, Options vested and exercisable | $ / shares	3.71
Weighted average exercise price, Options vested and expected to vest | $ / shares	$ 3.29
Share-based Compensation Arrangement by Share-based Payment Award, Options, Additional Disclosures [Abstract]
Weighted average remaining contractual term, Outstanding, balance	7 years 9 months 18 days
Weighted average remaining contractual term, Options vested and exercisable	7 years 4 months 24 days
Weighted average remaining contractual term, Options vested and expected to vest	7 years 9 months 7 days
Aggregate intrinsic value, Outstanding, Beginning balance | $	$ 0
Aggregate intrinsic value, Outstanding, Ending balance | $	17,961
Aggregate intrinsic value, Options vested and exercisable | $	9,438
Aggregate intrinsic value, Options vested and expected to vest | $	$ 17,177

Stock Benefit Plans and Stock_5

Stock Benefit Plans and Stock-Based Compensation - Summary of Information about Restricted Stock Awards, Restricted Stock Units and Performance-Based Restricted Units Activity (Detail) - Restricted Stock - $ / shares shares in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number of Shares [Roll Forward]
Shares, Unvested beginning balance	3,270
Shares, Awarded	4,802
Shares, Vested	(1,224)
Shares, Forfeited	(121)
Shares, Unvested ending balance	6,727	3,270
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Weighted Average Grant Date Fair Value [Abstract]
Weighted average grant date fair value, Unvested beginning balance	$ 2.94
Weighted average grant date fair value, Awarded	1.92	$ 2.87
Weighted average grant date fair value, Vested	2.83
Weighted average grant date fair value, Forfeited	3.11
Weighted average grant date fair value, Unvested ending balance	$ 2.17	$ 2.94
Weighted average remaining recognition period (in years)	2 years 3 months 25 days

Stock Benefit Plans and Stock_6

Stock Benefit Plans and Stock-Based Compensation - Summary Common Stock Reserved for Future Issuance (Detail) shares in Thousands	Dec. 31, 2019shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Common stock reserved for future issuance	43,664
Employee Stock Option
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Common stock reserved for future issuance	4,215
Unvested restricted stock awards
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Common stock reserved for future issuance	6,727
Employee Stock Purchase Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Common stock reserved for future issuance	117
Series A Convertible Preferred Stock
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Common stock reserved for future issuance	67
Warrants Outstanding
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Common stock reserved for future issuance	26,557
Authorized for Future Grant Under the Distributor and Development Services Plans
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Common stock reserved for future issuance	3,908
Authorized for Future Grant Under the Management Objective Strategic Incentive Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Common stock reserved for future issuance	445
Authorized for Future Grant Under the Plans
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Common stock reserved for future issuance	1,628

Income Taxes - Components of Pr

Income Taxes - Components of Pretax Income (Loss) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Income Tax Disclosure [Abstract]
U.S. Domestic	$ (57,141)	$ (30,169)
Foreign	(100)	(167)
Pretax loss from operations	$ (57,241)	$ (30,336)

Income Taxes - Components of (B

Income Taxes - Components of (Benefit) Provision for Income Taxes from Continuing Operations (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Current income tax (benefit) provision:
Federal		$ (64)
State	$ 207	86
Foreign		4
Total current	207	26
Deferred income tax benefit:
Federal	(195)	(1,140)
State	(251)	(247)
Total deferred	(446)	(1,387)
Total income tax benefit	$ (239)	$ (1,361)

Income Taxes - Schedule of Effe

Income Taxes - Schedule of Effective Income Tax Rate Reconciliation (Details)	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Income Tax Disclosure [Abstract]
Federal statutory rate	21.00%	21.00%
Adjustments for tax effects of:
State taxes, net	0.12%	0.47%
Stock-based compensation	0.26%	(4.29%)
R&D credit expiration	(5.96%)
Fair market value adjustments		(0.59%)
Other permanent adjustments	(0.42%)	(0.56%)
Foreign partnership liquidation	19.19%
Federal uncertain tax positions	3.25%	0.30%
NOL expiration	(3.01%)
Other	1.16%	(1.57%)
Valuation allowance	(35.09%)	(10.25%)
Effective income tax rate	0.50%	4.51%

Income Taxes - Significant Comp

Income Taxes - Significant Components of Company's Deferred Tax Assets and Liabilities (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Deferred tax assets:
Accruals and reserves	$ 2,730	$ 1,133
Income tax credit carryforwards	1,591	3,150
Interest	4,095	1,351
Inventory	8,625	4,959
Legal settlement	3,789	4,693
Net operating losses	53,592	45,092
Stock-based compensation	2,256	1,182
Total deferred tax assets	76,678	61,560
Valuation allowance	(71,159)	(46,578)
Total deferred tax assets, net of valuation allowance	5,519	14,982
Deferred tax liabilities:
Property and equipment	(3,117)	(21)
Goodwill and intangibles	(2,344)	(1,972)
Investment in foreign partnership		(13,370)
Total deferred tax liabilities	(5,461)	(15,363)
Net deferred tax assets	$ 58
Net deferred tax (liabilities)		$ (381)

Income Taxes - Additional Infor

Income Taxes - Additional Information (Details) - USD ($)	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Income Tax [Line Items]
Deferred tax asset, valuation allowance	$ 71,159,000	$ 46,578,000
Number of years cumulative pre-tax loss	3 years
Indefinite-lived intangible assets	$ 0
Unrecognized tax benefits	2,452,000	$ 4,334,000	$ 4,440,000
Accrued interest and penalties	0
Operating loss carryforwards state	205,200,000
Operating loss carryforwards federal	128,200,000
Federal and state net operating loss carryforwards, expiring year		2039
State research and development tax credit carryforwards	$ 3,200,000
Cumulative change in ownership percentage	50.00%
Period for cumulative change in ownership	3 years
Federal
Income Tax [Line Items]
Deferred tax asset, valuation allowance increase (decrease)	$ 20,100,000
State
Income Tax [Line Items]
Deferred tax asset, valuation allowance increase (decrease)	$ 4,500,000

Income Taxes - Summary of Chang

Income Taxes - Summary of Changes to Unrecognized Tax Benefits (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Reconciliation of Unrecognized Tax Benefits, Excluding Amounts Pertaining to Examined Tax Returns [Roll Forward]
Unrecognized tax benefit at the beginning of the year	$ 4,334	$ 4,440
Reductions as a result of lapse of applicable statute of limitations	(1,882)	(106)
Unrecognized tax benefits at the end of the year	$ 2,452	$ 4,334

Related Party Transactions - Ad

Related Party Transactions - Additional Information (Details) - USD ($) $ in Thousands	Jul. 01, 2016	Aug. 13, 2014	Sep. 30, 2014	Apr. 30, 2014	Mar. 31, 2014	Dec. 31, 2019	Dec. 31, 2018
Related Party Transaction [Line Items]
Settlement amount to be contributed						$ 5,000	$ 5,000
Withholding tax receivable from officer							350
Restricted Stock Units
Related Party Transaction [Line Items]
Withholding tax receivable from officer							300
Orthotec LLC, litigation settlement
Related Party Transaction [Line Items]
Payments of settlement				$ 15,750	$ 1,750	40,600
Judgment assessed by court for (against) company		$ (49,000)
Orthotec LLC, litigation settlement | HealthpointCapital, LLC
Related Party Transaction [Line Items]
Payments of settlement	$ 1,000					1,100
Judgment assessed by court for (against) company			$ (5,000)
Settlement amount to be contributed						$ 5,000	$ 5,000

Retirement Plan - Additional In

Retirement Plan - Additional Information (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Defined Contribution Plan Disclosure [Line Items]
Matching contributions by employer	4.00%
Employer matching contribution, vesting period	1 year
Section 401(k) plan
Defined Contribution Plan Disclosure [Line Items]
Total contributions	$ 0.6	$ 0.4

Restructuring Activities - Roll

Restructuring Activities - Rollforward of accrued restructuring liability (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Restructuring And Related Activities [Abstract]
Beginning balance	$ 710
Accrued restructuring charges	60	$ 1,381
Payments	(746)
Ending balance	$ 24	$ 710

Subsequent Event - Additional I

Subsequent Event - Additional Information (Details) $ / shares in Units, $ in Millions	Feb. 28, 2020USD ($)$ / sharesshares	Feb. 28, 2020€ / shares	Dec. 31, 2019$ / sharesshares	Dec. 31, 2018$ / sharesshares
Subsequent Event [Line Items]
Common stock, shares | shares			61,718,000	43,518,000
Common stock, par value | $ / shares			$ 0.0001	$ 0.0001
Subsequent Event | Commitment Letter | Perceptive Credit Holdings III, LP
Subsequent Event [Line Items]
Secured debt financing | $	$ 130
Subsequent Event | Commitment Letter | Perceptive Credit Holdings III, LP | Refinancing Warrants
Subsequent Event [Line Items]
Percentage of warrant price per share	50.00%
Volume weighted average price, period	5 days
Warrant floor price per share | $ / shares	$ 4.60
Percentage of remaining warrant price per share	50.00%
Percentage of warrant premium	12.50%
Subsequent Event | Commitment Letter | Perceptive Credit Holdings III, LP | Tender Offer Warrants
Subsequent Event [Line Items]
Percentage of warrant price per share	50.00%
Volume weighted average price, period	5 days
Warrant floor price per share | $ / shares	$ 4.60
Percentage of remaining warrant price per share	50.00%
Percentage of warrant premium	12.50%
Subsequent Event | Commitment Letter | Perceptive Credit Holdings III, LP | Supplemental Warrants
Subsequent Event [Line Items]
Percentage of warrant price per share	50.00%
Volume weighted average price, period	5 days
Warrant floor price per share | $ / shares	$ 4.60
Percentage of remaining warrant price per share	50.00%
Percentage of warrant premium	12.50%
Subsequent Event | Commitment Letter | Refinancing Portion | Perceptive Credit Holdings III, LP
Subsequent Event [Line Items]
Percentage of aggregate principal amount	18.50%
Subsequent Event | Commitment Letter | Refinancing Portion | Perceptive Credit Holdings III, LP | Maximum
Subsequent Event [Line Items]
Secured debt financing | $	$ 60
Subsequent Event | Commitment Letter | Tender Offer Portion | Perceptive Credit Holdings III, LP
Subsequent Event [Line Items]
Secured debt financing | $	$ 70
Percentage of aggregate principal amount	9.00%
Subsequent Event | Commitment Letter | Tender Offer Portion | Perceptive Credit Holdings III, LP | Maximum
Subsequent Event [Line Items]
Secured debt financing | $	$ 100
Subsequent Event | Commitment Letter | Supplemental Portion | Perceptive Credit Holdings III, LP
Subsequent Event [Line Items]
Percentage of aggregate principal amount	9.00%
Subsequent Event | Commitment Letter | Supplemental Portion | Perceptive Credit Holdings III, LP | Maximum
Subsequent Event [Line Items]
Secured debt financing | $	$ 15
Subsequent Event | Tender Offer Agreement | EOS Imaging S.A
Subsequent Event [Line Items]
Share price | € / shares		€ 0.01
Tender offer price | (per share)	$ 3.08	2.80
Common stock, shares | shares	0.50
Common stock, par value | $ / shares	$ 0.0001
Subsequent Event | Tender Offer Agreement | OCEANEs | EOS Imaging S.A
Subsequent Event [Line Items]
Tender offer price | (per share)	$ 7.71	€ 7.01