Venus Concept (VERO) 10-K 20 Mar 19 2018 FY Annual report Financial data

Document and Entity Information

Document and Entity Information - USD ($)	12 Months Ended
	Dec. 31, 2018	Feb. 28, 2019	Jun. 29, 2018
Document And Entity Information [Abstract]
Document Type	10-K
Amendment Flag	false
Document Period End Date	Dec. 31, 2018
Document Fiscal Year Focus	2018
Document Fiscal Period Focus	FY
Trading Symbol	HAIR
Entity Registrant Name	Restoration Robotics, Inc.
Entity Central Index Key	0001409269
Current Fiscal Year End Date	--12-31
Entity Filer Category	Non-accelerated Filer
Entity Shell Company	false
Entity Small Business	true
Entity Emerging Growth Company	true
Entity Ex Transition Period	false
Entity Common Stock, Shares Outstanding		40,767,012
Entity Well-known Seasoned Issuer	No
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes
Entity Public Float			$ 66,841,767

Consolidated Balance Sheets

Consolidated Balance Sheets - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
CURRENT ASSETS:
Cash and cash equivalents	$ 16,122	$ 23,545
Accounts receivable, net of allowance of $1,772 and $229 as of December 31, 2018 and 2017	6,569	3,864
Inventory	5,522	2,761
Prepaid expenses and other current assets	1,278	1,562
Total current assets	29,491	31,732
Property and equipment, net	1,299	1,138
Restricted cash	83	100
Other assets	100
TOTAL ASSETS	30,973	32,970
CURRENT LIABILITIES:
Accounts payable	3,815	2,044
Accrued compensation	1,771	1,630
Other accrued liabilities	2,337	1,125
Deferred revenue	1,407	1,517
Current portion of long-term debt, net of discount of $617 and $270 as of December 31, 2018 and 2017	49	7,730
Total current liabilities	9,379	14,046
Other long-term liabilities	594	459
Long-term debt, net of discount of $746 and $29 as of December 31, 2018 and 2017	19,418	5,271
TOTAL LIABILITIES	29,391	19,776
Commitments and Contingencies (Note 6)
STOCKHOLDERS’ EQUITY:
Preferred stock, $0.0001 par value: 10,000,000 shares authorized as of December 31, 2018 and 2017; no shares issued and outstanding as of December 31, 2018 and 2017
Common stock, $0.0001 par value: 300,000,000 shares authorized as of December 31, 2018 and 2017; 40,677,012 and 28,940,282 shares issued and outstanding as of December 31, 2018 and 2017	4	3
Additional paid-in capital	194,841	177,757
Accumulated other comprehensive loss	(50)	(79)
Accumulated deficit	(193,213)	(164,487)
TOTAL STOCKHOLDERS’ EQUITY	1,582	13,194
TOTAL LIABILITIES AND STOCKHOLDERS’ EQUITY	$ 30,973	$ 32,970

Consolidated Balance Sheets (Pa

Consolidated Balance Sheets (Parenthetical) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Statement Of Financial Position [Abstract]
Accounts receivable, allowance	$ 1,772	$ 229
Current portion of long-term debt, discount	617	270
Long-term debt, discount	$ 746	$ 29
Preferred stock, par value	$ 0.0001	$ 0.0001
Preferred stock, shares authorized	10,000,000	10,000,000
Preferred stock, shares issued	0	0
Preferred stock, shares outstanding	0	0
Common stock, par value	$ 0.0001	$ 0.0001
Common stock, shares authorized	300,000,000	300,000,000
Common stock, shares issued	40,677,012	28,940,282
Common stock, shares outstanding	40,677,012	28,940,282

Consolidated Statements of Oper

Consolidated Statements of Operations - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Income Statement [Abstract]
Revenue	$ 21,956	$ 21,297	$ 15,600
Cost of revenue	12,450	12,150	10,431
Gross profit	9,506	9,147	5,169
Operating expenses:
Sales and marketing	18,204	14,390	12,483
Research and development	8,374	7,135	7,474
General and administrative	8,834	4,904	4,144
Total operating expenses	35,412	26,429	24,101
Loss from operations	(25,906)	(17,282)	(18,932)
Other income (expense), net:
Interest expense	(2,224)	(2,027)	(2,483)
Gain on sale of investment		1,851
Other expense, net	(549)	(328)	(431)
Total other income (expense), net	(2,773)	(504)	(2,914)
Net loss before provision for income taxes	(28,679)	(17,786)	(21,846)
Provision for income taxes	47	56
Net loss	$ (28,726)	$ (17,842)	$ (21,846)
Net loss per share, basic and diluted	$ (0.86)	$ (2.42)	$ (13.54)
Weighted-average shares used in computing net loss per share, basic and diluted	33,512,181	7,382,715	1,612,933

Consolidated Statements of Comp

Consolidated Statements of Comprehensive Loss - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Statement Of Income And Comprehensive Income [Abstract]
Net loss	$ (28,726)	$ (17,842)	$ (21,846)
Other comprehensive income (loss):
Cumulative translation adjustment	29	(93)
Comprehensive loss	$ (28,697)	$ (17,935)	$ (21,846)

Consolidated Statement of Conve

Consolidated Statement of Convertible Preferred Stock and Stockholders' Equity (Deficit) - USD ($) $ in Thousands	Total	Common Stock	Additional Paid-in Capital	Accumulated Other Comprehensive Income (Loss)	Accumulated Deficit	Convertible Preferred Stock
Beginning balance, value at Dec. 31, 2015						$ 123,662
Beginning balance, shares at Dec. 31, 2015						19,336,777
Beginning balance, value at Dec. 31, 2015	$ (122,205)		$ 2,580	$ 14	$ (124,799)
Beginning balance, shares at Dec. 31, 2015		1,595,277
Issuance of common stock pursuant to stock option exercises of vested options	$ 41		41
Issuance of common stock pursuant to stock option exercises of vested options, shares	20,218	20,218
Issuance of Series C convertible preferred stock for cash, net of issuance costs, value						$ 12,073
Issuance of Series C convertible preferred stock for cash, net of issuance costs, shares						1,805,518
Stock-based compensation	$ 466		466
Net loss	(21,846)				(21,846)
Ending balance, value at Dec. 31, 2016						$ 135,735
Ending balance, shares at Dec. 31, 2016						21,142,295
Ending balance, value at Dec. 31, 2016	(143,544)		3,087	14	(146,645)
Ending balance, shares at Dec. 31, 2016		1,615,495
Issuance of common stock pursuant to stock option exercises of vested options	$ 43		43
Issuance of common stock pursuant to stock option exercises of vested options, shares	21,843	21,843
Issuance of Series C convertible preferred stock for cash, net of issuance costs, value						$ 10,209
Issuance of Series C convertible preferred stock for cash, net of issuance costs, shares						1,529,306
Stock-based compensation	$ 465		465
Adjustment for fractional shares from reverse stock split, shares		137
Reclassification of preferred stock warrant liabilities to additional paid in capital	1,080		1,080
Conversion of convertible notes to common stock, value	5,027		5,027
Conversion of convertible notes to common stock, shares		718,184
Conversion of preferred stock to common stock upon initial public offering, value	145,944	$ 3	145,941			$ (145,944)
Conversion of preferred stock to common stock upon initial public offering, shares		22,671,601				(22,671,601)
Issuance of common stock in connection with initial public offering and follow-on offering, net of issuance costs, value	22,114		22,114
Issuance of common stock in connection with initial public offering and follow-on offering, net of issuance costs, shares		3,897,910
Issuance of common stock upon exercise of common stock warrants, shares		15,112
Other comprehensive gain (loss)	(93)			(93)
Net loss	(17,842)				(17,842)
Ending balance, value at Dec. 31, 2017	13,194	$ 3	177,757	(79)	(164,487)
Ending balance, shares at Dec. 31, 2017		28,940,282
Issuance of common stock pursuant to stock option exercises of vested options	$ 392		392
Issuance of common stock pursuant to stock option exercises of vested options, shares	236,730	236,730
Stock-based compensation	$ 667		667
Issuance of common stock warrants pursuant to debt financing	466		466
Issuance of common stock in connection with initial public offering and follow-on offering, net of issuance costs, value	15,560	$ 1	15,559
Issuance of common stock in connection with initial public offering and follow-on offering, net of issuance costs, shares		11,500,000
Other comprehensive gain (loss)	29			29
Net loss	(28,726)				(28,726)
Ending balance, value at Dec. 31, 2018	$ 1,582	$ 4	$ 194,841	$ (50)	$ (193,213)
Ending balance, shares at Dec. 31, 2018		40,677,012

Consolidated Statement of Con_2

Consolidated Statement of Convertible Preferred Stock and Stockholders' Equity (Deficit) (Parenthetical) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Issuance of common stock in connection with initial public offering and follow-on offering, issuance costs	$ 1,690	$ 5,171
Convertible Preferred Stock
Issuance of Series C convertible preferred stock for cash, issuance costs		$ 726	$ 837

Consolidated Statements of Cash

Consolidated Statements of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
CASH FLOWS FROM OPERATING ACTIVITIES:
Net loss	$ (28,726)	$ (17,842)	$ (21,846)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation and amortization	813	574	654
Loss on disposal of property and equipment		34	46
Amortization of debt discounts and issuance costs	470	551	737
Loss on extinguishment of debt	178
Stock-based compensation	667	465	466
Changes in fair value of preferred stock warrant liabilities		387	346
Gain on sale of investment		(1,851)
Non-cash interest expense on convertible notes		27
Provision for bad debt	1,772	229
Changes in operating assets and liabilities:
Accounts receivable	(4,478)	(1,612)	(987)
Inventory	(2,761)	(19)	2,892
Prepaid expenses and other assets	185	(752)	324
Accounts payable	1,802	246	709
Deferred revenue	144
Accrued and other liabilities	1,235	307	495
Net cash used in operating activities	(28,699)	(19,256)	(16,164)
CASH FLOWS FROM INVESTING ACTIVITIES:
Proceeds from sale of property and equipment			2
Proceeds from sale of investment		1,851
Purchases of property and equipment	(1,006)	(229)	(1,173)
Net cash provided by (used in) investing activities	(1,006)	1,622	(1,171)
CASH FLOWS FROM FINANCING ACTIVITIES:
Proceeds from issuance of common stock upon initial public offering, net		22,114
Proceeds from convertible notes		5,000
Proceeds from issuance of Series C convertible preferred stock, net		10,209	12,073
Proceeds from issuance of common stock upon follow-on offering, net	15,560
Proceeds from exercised stock options	392	43	41
Proceeds from long-term debt, net	19,584
Principal payments on long-term debt	(13,300)	(8,000)
Net cash provided by financing activities	22,236	29,366	12,114
Effect of exchange rate changes on cash, cash equivalents and restricted cash	29	(93)
NET INCREASE (DECREASE) IN CASH, CASH EQUIVALENTS AND RESTRICTED CASH	(7,440)	11,639	(5,221)
CASH, CASH EQUIVALENTS AND RESTRICTED CASH — Beginning of period	23,645	12,006	17,227
CASH, CASH EQUIVALENTS AND RESTRICTED CASH — End of period	16,205	23,645	12,006
SUPPLEMENTAL DISCLOSURES OF CASH FLOW INFORMATION:
Cash paid for income taxes	35	28	56
Cash paid for interest	1,757	1,497	$ 1,738
SUPPLEMENTAL DISCLOSURES OF NON-CASH INVESTING AND FINANCING INFORMATION:
Property and equipment purchased through AP and accrued liabilities	25	58
Discounts and issuance costs in connection with long-term debt	1,246
Conversion of preferred stock into common stock		145,944
Reclassification of preferred stock warrant liabilities to equity		1,080
Conversion of convertible notes and accrued interest into common stock		$ 5,027
Issuance of warrants in connection with long-term debt	$ 466

Nature of Operations

Nature of Operations	12 Months Ended
	Dec. 31, 2018
Organization Consolidation And Presentation Of Financial Statements [Abstract]
Nature of Operations	1. Nature of Operations Restoration Robotics, Inc. is a medical device company incorporated in the state of Delaware on November 22, 2002 and headquartered in San Jose, California. The Company develops an image-guided robotic system that enables follicular unit extraction (FUE) for use in the field of hair transplantation and markets the ARTAS ® Initial Public Offering On October 11, 2017, the Company’s Registration Statement on Form S-1 (File No. 333-220303) relating to the initial public offering (IPO) of its common stock was declared effective by the Securities and Exchange Commission (SEC). Pursuant to such Registration Statement, the Company completed its IPO of 3,897,910 shares of its common stock (inclusive of 322,910 shares of common stock from the subsequent exercise of the over-allotment option granted to the underwriters) at a price of $7.00 per share for aggregate net cash of approximately $22,114, after deducting underwriter discounts and commissions, and offering costs of $5,171. Immediately prior to the closing of the IPO, all outstanding shares of convertible preferred stock converted into 22,671,601 shares of common stock and all the outstanding convertible preferred stock warrants converted into common stock warrants resulting in the reclassification of our preferred stock warrant liabilities to additional paid-in capital. In addition, the principal and accrued interest on the outstanding Convertible Notes converted into 718,184 shares of common stock. The IPO closed on October 16, 2017. Following the filing of the Restated Certificate of Incorporation of the Company on October 16, 2017, the number of shares of capital stock the Company is authorized to issue is 310,000,000 shares, of which 300,000,000 shares may be common stock and 10,000,000 shares may be preferred stock. Both the common stock and the preferred stock have a par value of $0.0001 per share. Follow-on Public Offering On August 16, 2018, the Company closed its follow-on public offering of 10,000,000 shares of its common stock, plus 1,500,000 shares of common stock from the subsequent exercise of the over-allotment option granted to the underwriters. The public offering price of the shares sold was $1.50 per share. The Company received aggregate net cash of approximately $15,560 from the follow-on offering, after deducting underwriting discounts and commissions and offering costs totaling $1,690. The Company is using the net proceeds from this offering (including net proceeds from the underwriters’ exercise of their option to purchase additional shares of common stock) to fund expanded commercialization activities in connection with our recently launched ARTAS ® Reverse Stock Split On September 15, 2017, the Company effected a 1-for-10 reverse stock split of its common stock. Upon the effectiveness of the reverse stock split, (i) every 10 shares of outstanding common stock were combined into one share of common stock, (ii) the number of shares of common stock for which each outstanding option to purchase common stock is exercisable was proportionately decreased on a 1-for-10 basis, (iii) the exercise price of each outstanding option to purchase common stock was proportionally increased on a l-for-10 basis, and (iv) the conversion ratio for each share of outstanding preferred stock which is convertible into our common stock was proportionately reduced on a 1-for-10 basis. All the outstanding common stock share numbers (including shares of common stock into which our outstanding convertible preferred stock shares are convertible), share prices, exercise prices and per share amounts have been adjusted in these consolidated statements, on a retroactive basis, to reflect this l-for-10 reverse stock split for all periods presented. The par value per share and the authorized number of shares of common stock and convertible preferred stock were not adjusted as a result of the reverse stock split.

Summary of Significant Accounti

Summary of Significant Accounting Policies	12 Months Ended
	Dec. 31, 2018
Accounting Policies [Abstract]
Summary of Significant Accounting Policies	2. SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES Liquidity These consolidated financial statements are prepared on a going concern basis that contemplates the realization of assets and extinguishment of liabilities in the normal course of business. The Company has incurred net operating losses and negative cash flows from operations since inception. As of December 31, 2018, and 2017, the Company has an accumulated deficit of $193,213 and $164,487 and, as of such dates, did not have sufficient capital to fund its planned operations. As a result of the Company’s recurring losses from operations and negative cash flows, the Company’s independent registered public accounting firm included an explanatory paragraph in its current report on the Company’s consolidated financial statements that such factors raise substantial doubt about the Company’s ability to continue as a going concern. Management plans to manage expenses and obtain additional funds through a combination of equity and debt financing. The Company will need to raise further capital in the future to service its debt and fund its operations until the time it can sustain positive cash flows. There can be no assurance that the Company will be successful in raising additional capital or that such capital, if available, will be on terms that are acceptable to the Company. If the Company is unable to raise sufficient additional capital, it may be compelled to reduce the scope of its operations and planned capital expenditures or sell certain assets, including intellectual property assets. The accompanying consolidated financial statements have been prepared on a going concern basis, which contemplates the realization of assets and the satisfaction of liabilities in the normal course of business, and, as such, the consolidated financial statements do not include any adjustments relating to the recoverability and classification of recorded asset amounts or amounts and classification of liabilities that might be necessary should the Company be unable to continue in existence. Basis of Presentation The accompanying consolidated financial statements have been prepared in accordance with generally accepted accounting principles in the United States of America (U.S. GAAP). The accompanying consolidated financial statements include the accounts of Restoration Robotics, Inc. and its wholly owned subsidiaries. Principles of Consolidation The accompanying consolidated financial statements include the accounts of Restoration Robotics, Inc. and its wholly owned subsidiaries, which are located in the United States, United Kingdom, Spain, Hong Kong and South Korea. All significant intercompany accounts and transactions have been eliminated in consolidation. Reclassification Accrued compensation, which was previously included in other accrued liabilities in the prior year's consolidated balance sheet has been reclassified to conform to the current period's presentation. The reclassification had no impact on the previously reported consolidated balance sheet for the year ended December 31, 2017. The provision for bad debt, which was previously included in accounts receivable in the prior year’s consolidated statements of cash flow has been reclassified to conform to the current period’s presentation. The reclassification had no impact on the previously reported consolidated statements of cash flow for the year ended December 31, 2017. Use of Estimates The preparation of the consolidated financial statements in conformity with U.S. GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities as of the date of the consolidated financial statements and the reported amounts of revenue and expenses during the reporting period. Significant estimates and assumptions made in the accompanying consolidated financial statements include, but are not limited to revenue recognition, allowance for doubtful accounts, inventory valuation, stock-based compensation, warranty accrual and the recoverability of the Company’s net deferred tax assets. The Company evaluates its estimates and assumptions on an ongoing basis using historical experience and other factors and adjusts those estimates and assumptions when facts and circumstances dictate. Actual results could materially differ from those estimates. Foreign Currency The functional currency of the Company’s non-U.S. subsidiaries is the local currency. Asset and liability balances denominated in non-U.S. dollar currencies are translated into U.S. dollars using period-end exchange rates, while revenue and expenses are based upon the exchange rate at the time of the transaction, if known, or at the average rate for the period. Differences are included in stockholders’ equity (deficit) as a component of accumulated other comprehensive loss. Financial assets and liabilities denominated in currencies other than the functional currency are recorded at the exchange rate at the time of the transaction and subsequent gains and losses related to changes in the foreign currency are included in other income (expense), net in the accompanying consolidated statements of operations. The net foreign transaction gain or losses were insignificant for all periods presented. Cash and Cash Equivalents The Company considers all highly liquid investments with an original maturity of three months or less from the date of purchase to be cash equivalents. Cash and cash equivalents consist primarily of funds invested in readily available checking and savings accounts, investments in money market funds and short-term time deposits. Restricted Cash As of December 31, 2018, and 2017, the Company was required to hold $83 and $100, respectively, in a separate money market account as collateral for credit cards. Concentration of Credit Risk Financial instruments that potentially subject the Company to a concentration of credit risk consist of cash and cash equivalents, restricted cash and accounts receivable. Substantially all of the Company’s cash and cash equivalents and restricted cash are held with two financial institutions, and the account balances exceed the Federal Deposit Insurance Corporation (FDIC) insurance limit. Accounts are insured by the FDIC up to $250 per financial institution. The Company has not experienced any losses in such accounts with these financial institutions. Concentration of Customers For the years ended December 31, 2018, 2017 and 2016, there were no customers accounting for more than 10% of the Company’s revenue. As of December 31, 2018, there were no customers accounting for more than 10% of the Company’s accounts receivable. As of December 31, 2017, two customers each accounted for 10% and 11% of the Company’s accounts receivable. Allowance for Doubtful Accounts Accounts receivable do not bear interest and are typically not collateralized. The Company performs ongoing credit evaluations of its customers’ financial condition and maintains an allowance for doubtful accounts. Uncollectible accounts are charged to expense when deemed uncollectible, and accounts receivable are presented net of an allowance for doubtful accounts. Accounts receivable are deemed past due in accordance with the contractual terms of the agreement. Actual The allowance for doubtful accounts consisted of the following activity for years ended December 31, 2018 and 2017 (in thousands): As of December 31, 2018 2017 Balance at Beginning of Year $ 229 $ — Charge to expense 1,772 229 Write-offs, net of recoveries (229 ) — Balance at End of Year $ 1,772 $ 229 Inventory Inventory is stated at the lower of cost or net realizable value and cost is principally determined using the first-in, first-out method. Costs include material, labor and overhead. Inventory that is obsolete or in excess of forecasted usage is written down to its estimated net realizable value based on assumptions about future demand and market conditions. Inventory write-downs are charged to cost of goods sold and a new cost basis for the inventory is established. Property and Equipment Property and equipment are stated at cost, net of accumulated depreciation and amortization. Depreciation and amortization are computed using the straight-line method over the estimated useful lives of the assets, which is between three and five years. Leasehold improvements are amortized over the lesser of the life of the lease or the useful life of the improvements. Maintenance and repairs are charged to expense as incurred. When assets are retired or otherwise disposed of, the cost and accumulated depreciation are removed from the consolidated balance sheet, and any resulting gain or loss is reflected in operations. Impairment of Long-Lived Assets Property and equipment are reviewed annually for impairment or whenever events or changes in circumstances indicate that the carrying amount of an asset may not be recoverable. Recoverability is measured by comparison of the carrying amount to the future net undiscounted cash flows that the assets are expected to generate. If the carrying amount of an asset group exceeds its estimated future cash flows, an impairment charge is recognized in the amount by which the carrying amount of the asset group exceeds the fair value of the asset group. If such assets are considered to be impaired, the impairment to be recognized is measured by the amount by which the carrying amount of the assets exceeds the projected discounted future net cash flows arising from the asset. There has been no impairment of long-lived assets for any of the periods presented. Debt Issuance Costs Costs related to the issuance of debt are presented as a direct deduction to the carrying value of the debt and are amortized to interest expense using the effective interest rate method over the term of the related debt. Gain on Sale of Stock Investment In the fourth quarter of 2017, the Company recognized a gain of $1,851 on the sale of stock held in a privately-held company that had been impaired and written-down to nil prior to fiscal year 2014. Revenue Recognition The Company generates revenue from sales of robotic systems and related procedures, and related support and maintenance. The Company derives revenue primarily from two sources: (i) Product revenue, which consist of the sale of the ARTAS System, procedure kits, upgrades and training; and (ii) Support and maintenance revenue, which primarily consist of our ARTAS Care (i.e. extended warranty service contracts). Revenue is recognized when all of the following criteria are met: (l) persuasive evidence of an arrangement exists; (2) the product or service has been delivered; (3) the sales price is fixed or determinable; and (4) collection is reasonably assured. The Company defines each of the four criteria above as follows: • Persuasive Evidence of Arrangement Exists . The Company uses purchase orders pursuant to the terms and conditions of a master agreement to support the evidence of an arrangement with distributors and uses purchase agreements as evidence of arrangement with direct customers. • Delivery has Occurred . Provided that all other revenue recognition criteria have been met the Company typically recognizes system revenue upon shipment for systems as title and risk of loss are transferred at that time, and there are no further obligations and no rights of return. Prior to January 1, 2018, the Company typically recognized system revenue upon customer acceptance for sales to direct customers. This change in accounting was as a result of a change in business process, which included the shipment of fully assembled systems starting in 2018. Procedure revenue is recognized upon shipment of disposable kits and delivery of the ARTAS key, if applicable. ARTAS Care (extended warranty contracts) are recognized over time as the services are delivered. • The Sales Price is Fixed or Determinable . The Company assesses whether the fee is fixed or determinable based on the payment terms associated with the transaction. If the terms are extended beyond the Company’s normal payment terms, the Company will recognize revenue as the payments become due. Payments from distributors are not contingent on the distributors’ receiving payment from the end-users. • Collection is Reasonably Assured . The Company assesses probability of collection on an individual basis based on a number of factors, including the credit-worthiness of the customer and past transaction history with the customer. The Company generally obtains a significant cash deposit from its customers prior to shipment. The Company records its revenue net of sales tax and shipping and handling costs. Incremental direct costs incurred related to the acquisition or origination of a customer contract are expensed as incurred. Multiple Element Arrangements The Company’s offering includes robotic systems containing software components that function together to provide the essential functionality of the product. Therefore, the Company’s hardware products (inclusive of the core software) are considered non-software deliverables and are not subject to industry-specific software revenue recognition guidance. The Company’s typical multiple element arrangement generally includes robotic systems (including the essential software), procedure key, product training, and procedure kits. The Company considers each of these deliverables to be separate units of accounting based on whether the delivered items have stand-alone value. The Company has determined that each unit of accounting has stand-alone value because they are sold separately by the Company or, for hardware products, because the customers can resell them to others on a stand-alone basis. For the arrangements with multiple deliverables, the Company allocates the arrangement fee to each element based upon the relative selling price of such element. When applying the relative selling price method, the Company determines the selling price for each element using vendor-specific objective evidence (VSOE) of selling price, if it exists, or if not, third-party evidence (TPE) of selling price, if it exists. If neither VSOE nor TPE of selling price exist for an element, the Company uses its best estimated selling price (BESP) for that element. The revenue allocated to each element is then recognized when the basic revenue recognition criteria are met for that element. The Company is not able to establish a selling price of its deliverables using VSOE or to determine TPE for its products and services. TPE is determined based on competitor prices for similar deliverables when sold separately. Generally, the Company’s go-to-market strategy differs from that of its peers and its offerings contain a significant level of differentiation such that the comparable pricing of products with similar functionality cannot be obtained. When the Company is unable to establish the selling price of its deliverables using VSOE or TPE, the Company uses BESP in its allocation of arrangement consideration. The objective of BESP is to determine the price at which the Company would transact a sale if the product or service were sold on a stand-alone basis. The Company determines BESP for a product or service by considering multiple factors including, but not limited to, industry and market conditions, competitive landscape, standard pricing practices and internal cost models. Additionally, the Company considers historical transactions, including transactions whereby the deliverable was sold on a stand-alone basis. Deferred revenue primarily relates to ARTAS Care (extended warranty) and training not yet provided to our customers. The current portion of deferred revenue represents the amounts that are expected to be recognized as revenue within one year of the consolidated balance sheet date. Cost of Revenue Cost of revenue consists of product and fulfillment costs. Product costs include the cost of systems and disposable kits manufacture, related labor and personnel costs and allocated shared costs. Fulfillment costs consist of costs incurred in the shipping and handling of inventory including the shipping costs to the Company's customers, labor and related personnel costs related to receiving, inspecting, warehousing, and preparing systems and reusable kits for shipment. Cost of revenue for customer service is expensed as incurred and primarily consists of personnel costs and related benefits for employees associated with service contracts, travel costs and allocated shared costs (including rent and information technology). Advertising Costs The cost of advertising and media is expensed as incurred. For the years ended December 31, 2018, 2017 and 2016, advertising costs totaled $297, $99 and $130, respectively. Research and Development Research and development costs are charged to operations as incurred. Major components of research and development expenses consist of personnel costs, including salaries and benefits, hardware and software research and development costs, regulatory affairs, and clinical costs. Warranty The Company provides a one-year warranty on the ARTAS ® Income Taxes Income taxes are accounted for under the asset and liability method. Deferred tax assets and liabilities are recognized for the future tax consequences attributable to differences between the tax and financial reporting bases of the Company’s assets and liabilities. Deferred tax assets and liabilities are measured using enacted tax rates expected to apply to taxable income in future years in which those temporary differences are expected to be recovered or settled. Deferred tax assets are reduced through the establishment of a valuation allowance, if, based upon available evidence, it is determined that it is more likely than not that the deferred tax assets will not be realized. All deferred tax assets and liabilities are classified as non-current in the consolidated financial statements. Uncertain Tax Positions The Company recognizes the effect of income tax positions only if those positions are more likely than not of being sustained on examination based on the technical merit of the position. The first step is to evaluate the tax position for recognition by determining if the weight of available evidence indicates it is more likely than not that the position will be sustained on examination, including resolution of related appeals or litigation processes, if any. The second step is to measure the tax benefit as the largest amount, which is more than 50% likely of being realized upon ultimate settlement. The Company considers many factors when evaluating and estimating its tax positions and tax benefits, which may require periodic adjustments. The Company recognizes interest charges and penalties related to unrecognized tax benefits as a component of the tax provision. Stock-Based Compensation The Company accounts for share-based compensation costs in accordance with the accounting standards for share-based compensation, which require that all share-based payments to employees be recognized in the consolidated statements of operations based on their fair values. • The fair value of stock options ("options") on the grant date is estimated using the Black-Scholes option-pricing model using the single-option approach. The Black-Scholes option pricing model requires the use of highly subjective and complex assumptions, including the option's expected term and the price volatility of the underlying stock, to determine the fair value of award. The Company recognizes the expense associated with options using a single-award approach over the requisite service period. • The fair value of Restricted Stock Awards ("RSAs") is based on the stock price on the grant date using a single-award approach. RSAs granted to non-employees are re-measured at the end of each reporting period based on the stock price on the last business day of the reporting period. The RSAs are subject to a service vesting condition and are recognized on a straight-line basis over the requisite service period, adjusted for any re-measurement changes at the end of each reporting period. No RSAs have been granted to employees. The Company recognizes share-based compensation expense for the portion of the equity award that is expected to vest over the requisite service period for those awards and develops an estimate of the number of share-based awards which will ultimately vest, primarily based on historical experience. The estimated forfeiture rate is reassessed periodically throughout the requisite service period. Such estimates are revised if they differ materially from actual forfeitures. As required, the forfeiture estimates will be adjusted to reflect actual forfeitures when an award vests. For the award types discussed above, if an employee terminates employment prior to being vested in an award, then the award is forfeited. Net Loss Per Share Prior to the conversion of all the preferred stock in connection with the IPO, the Company followed a two‑class method when computing net loss per common share as we issue shares that meet the definition of participating securities. The two‑class method determines net income (loss) per common share for each class of common stock and participating securities according to dividends declared or accumulated and participation rights in undistributed earnings. The two‑class method requires income for the period to be allocated between common stock and participating securities based upon their respective rights to receive dividends as if all income for the period had been distributed. The Company’s convertible preferred stock contractually entitles the holders of such shares to participate in dividends but does not contractually require the holders of such shares to participate in the Company’s losses. For periods in which the Company has reported net losses, diluted net loss per common share attributable to common stockholders is the same as basic net loss per common share attributable to common stockholders, because potentially dilutive common shares are not assumed to have been issued if their effect is anti‑dilutive. Defined Contribution Plan The Company offers a defined contribution retirement savings plan under Section 401(k) of the Internal Revenue Code (IRC). This plan covers employees who meet minimum age and service requirements and allows participants to defer a portion of their annual compensation on a pre-tax basis. Company contributions to the plan may be made at the discretion of the Board of Directors. There were no contributions by the Company during the years ended December 31, 2018, 2017 and 2016. JOBS Act Accounting Election The Company is an emerging growth company, as defined in the Jumpstart Our Business Startups Act of 2012, or the JOBS Act. Under the JOBS Act, emerging growth companies can delay adopting new or revised accounting standards issued subsequent to the enactment of the JOBS Act until such time as those standards apply to private companies. The Company has elected to use this extended transition period for complying with new or revised accounting standards that have different effective dates for public and private companies until the earlier of the date that it is (i) no longer an emerging growth company or (ii) affirmatively and irrevocably opt out of the extended transition period provided in the JOBS Act. As a result, these consolidated financial statements may not be comparable to companies that comply with the new or revised accounting pronouncements as of public company effective dates. Recently Issued Accounting Standards Not Yet Adopted In May 2014, the Financial Accounting Standards Board (FASB) issued ASU No. 2014‑09, Revenue from Contracts with Customers (Topic 606) In February 2016, the FASB issued ASU No. 2016‑02, Leases (Topic 842) In June 2018, the FASB issued ASU No. 2018-7, Compensation – Stock Compensation (Topic 718)— Improvements to Nonemployee Share-Based Payment Accounting

Net Loss per Share

Net Loss per Share	12 Months Ended
	Dec. 31, 2018
Earnings Per Share [Abstract]
Net Loss per Share	3. NET LOSS PER SHARE Net Loss Per Share Basic net loss per share is calculated by dividing net loss by the weighted-average number of common shares outstanding during the period, without consideration for common stock equivalents. Diluted net loss per share is computed by dividing net loss by the weighted-average number of common share equivalents outstanding for the period determined using the treasury-stock method. For purposes of this calculation, convertible preferred stock, preferred stock warrants and stock options are considered to be common stock equivalents and are only included in the calculation of diluted net loss per share when their effect is dilutive. Due to the net loss, all the outstanding shares of common stock equivalents were excluded from the calculation of diluted net loss per share attributable to common stockholders for the periods presented because including them would have been antidilutive: As of December 31, 2018 2017 2016 Options to purchase common stock 3,989,432 1,930,752 1,831,757 Convertible preferred stock — — 21,142,295 Warrants for preferred stock — — 385,126 Warrants for common stock 272,211 306,456 — Total potential dilutive shares 4,261,643 2,237,208 23,359,178

Fair Value Measurements

Fair Value Measurements	12 Months Ended
	Dec. 31, 2018
Fair Value Disclosures [Abstract]
Fair Value Measurements	4. FAIR VALUE MEASUREMENTS Fair value is defined as the price that would be received to sell an asset or paid to transfer a liability (an exit price) in an orderly transaction between market participants at the reporting date. The carrying amount of the Company’s debt approximates its fair value as of the balance sheet dates. The accounting guidance establishes a three-tiered hierarchy, which prioritizes the inputs used in the valuation methodologies in measuring fair value: Level - Quoted prices in active markets for identical assets or liabilities. Level - Inputs other than Level 1 that are observable, either directly or indirectly, such as quoted prices in markets that are not active, or other inputs that are observable or can be corroborated by observable market data for substantially the full term of the assets or liabilities. Level - Unobservable inputs that are supported by little or no market activity and that are significant to the fair value of the assets or liabilities. The categorization of a financial instrument within the valuation hierarchy is based on the lowest level of input that is significant to the fair value measurement. The Company classifies its cash equivalents and investments within Level 1 as it uses quoted market prices or alternative pricing sources and models utilizing market observable inputs. The following tables set forth the fair value of the Company’s financial assets and liabilities by level within the fair value hierarchy: Fair Value Measurements as of December 31, 2018 Quoted Prices in Active Markets using Identical Assets (Level 1) Significant Other Observable Inputs (Level 2) Significant Unobservable Inputs (Level 3) Total Assets Cash Equivalents: Money market account $ 13,968 $ — $ — $ 13,968 Restricted cash: Money market account 83 83 Total assets $ 14,051 $ — $ — $ 14,051 Fair Value Measurements as of December 31, 2017 Quoted Prices in Active Markets using Identical Assets (Level 1) Significant Other Observable Inputs (Level 2) Significant Unobservable Inputs (Level 3) Total Assets Cash Equivalents: (1) Money market account $ 18,728 $ — $ — $ 18,728 Restricted cash: Money market account 100 — — 100 Total assets $ 18,828 $ — $ — $ 18,828 (1) The Company incorrectly overstated its cash equivalents by $4,817 in the fair value measurements footnote of its annual report on Form 10-K for

Balance Sheet Components

Balance Sheet Components	12 Months Ended
	Dec. 31, 2018
Balance Sheet Components [Abstract]
Balance Sheet Components	5. BALANCE SHEET COMPONENTS Inventory Inventory December 31, 2018 2017 Raw materials $ 2,464 $ — Work-in-process 323 — Finished goods 2,735 2,761 Total inventory $ 5,522 $ 2,761 Inventory as of December 31, 2018, includes work-in-process and raw materials related to the Company’s next generation ARTAS iX System, which was launched and manufactured by the Company starting in the third quarter of 2018. All ARTAS Systems were exclusively manufactured by the Company’s contract manufacturer, Evolve Manufacturing Technologies, Inc., prior to the third quarter of 2018. Property and Equipment, Net Property December 31, 2018 2017 Computer hardware and software $ 901 $ 721 Equipment 3,531 2,929 Leasehold improvements 874 869 Furniture and fixtures 457 270 Total property and equipment 5,763 4,789 Less: Accumulated depreciation and amortization (4,464 ) (3,651 ) Total property and equipment, net $ 1,299 $ 1,138 Depreciation and amortization expense were $813, $574, $654 for the years ended December 31, 2018, 2017 and 2016.

Commitments and Contingencies

Commitments and Contingencies	12 Months Ended
	Dec. 31, 2018
Commitments And Contingencies Disclosure [Abstract]
Commitments and Contingencies	6. COMMITMENTS AND CONTINGENCIES Operating Leases The Company has various operating leases including 23,000 square feet of office space and 2,500 square feet of manufacturing space in San Jose, California, which expires in April 2022 and April 2019, respectively. The Company recognizes rent expense on a straight-line basis over the non-cancelable lease period and records the difference between cash rent payments and the recognition of rent expense as a deferred rent liability. When leases contain escalation clauses, rent abatements and/or concessions, such as rent holidays and landlord or tenant incentives or allowances, the Company applies them in the determination of straight-line rent expense over the lease period. Aggregate future minimum lease payments required under the Company’s operating leases as of December 31, 2018 are as follows: Years ending December 31, 2019 $ 518 2020 534 2021 550 2022 188 Thereafter — Total future minimum lease payments $ 1,790 The total rent expense for all operating leases for the years ended December 31, 2018, 2017 and 2016 was $564, $413, and $315. Licensing Agreements In July 2006, the Company entered into a license agreement with Rassman Licensing, LLC (Rassman) for non-exclusive, royalty bearing, non-transferable, perpetual, world-wide rights for use on approved fields relating to robotically controlled hair removal and implantation procedures. In consideration for this license, the Company paid Rassman a one-time payment of $1,000. The agreement, as amended, terminates on May 9, 2020. In February 2012, the Company amended its license agreement with Rassman. In exchange for a one-time $400 payment to Rassman, the Company now has a fully paid royalty-free license to a patent subject to this license agreement. Royalties for each of the years ended December 31, 2018, 2017 and 2016 were $0. In July 2006, the Company entered into a license agreement with HSC Development, LLC for exclusive non-transferable, royalty-free worldwide rights for use in approved fields relating to a computer-controlled system in which a device is carried on a mechanized arm for extraction or implantation of a follicular unit without manual manipulation. In consideration for this license, the Company paid HSC Development, LLC a one-time payment of $25 and issued 2,500 shares of the Company’s common stock. The agreement terminates on July 27, 2024. Commitments The Company has two master agreements and a component pricing agreement with Evolve Manufacturing Technologies, Inc. (Evolve) for the supply of the ARTAS ® ® In March 2018, the Company received U.S. FDA 510(k) clearance to expand the ARTAS ® ® ® Legal Proceedings From time to time the Company is involved in litigation arising out of claims in the normal course of business. Based on the information presently available, management believes that there are no claims or actions pending or threatened against us, the ultimate resolution of which will have a material effect on the Company’s financial position, liquidity or results of operations, although the results of litigation are inherently uncertain. Purported Shareholder Class Action On May 23, 2018, a putative shareholder class action complaint was filed in Superior Court of the State of California, County of San Mateo (the “Superior Court”), captioned Wong v. Restoration Robotics, Inc., et al., No. 18CIV02609. On June 21, 2018 and June 28, 2018, two putative class action complaints were filed in the United States District Court for the Northern District of California, captioned Guerrini v. Restoration Robotics, Inc., et al., No. 5:18-cv-03712-EJD and Yzeiraj v. Restoration Robotics, Inc., et al., No. 5:18-cv-03883-BLF, respectively. On July 24, 2018, the U.S. Northern District Court related the Guerrini and Yzeiraj actions and reassigned the Yzeiraj action to Judge Edward J. Davila. The Wong and Guerrini complaints name the Company as defendants, and certain of its current and former executive officers and directors, certain of its venture capital investors and the underwriters in the Company’s IPO. The Yzeiraj complaint names the Company as defendants and certain of its current and former executive officers and directors. The Wong complaint asserts claims under Sections 11, 12(a)(2) and 15 of the Securities Act of 1933, or the Securities Act. The Guerrini and Yzeiraj complaints assert claims under Sections 11 and 15 of the Securities Act. The complaints all allege, among other things, that the Company’s Registration Statement filed with the SEC on September 1, 2017 and the Prospectus filed with the SEC on October 13, 2017 in connection with the Company’s IPO were inaccurate and misleading, contained untrue statements of material facts, omitted to state other facts necessary to make the statements made not misleading and omitted to state material facts required to be stated therein. The complaints seek unspecified monetary damages, other equitable relief and attorneys’ fees and costs. On August 8, 2018, the Company, along with certain of its current and former executive officers and directors, filed a motion to dismiss the Wong complaint based on the forum selection clause designating the federal district courts as the exclusive forum for claims arising under the Securities Act contained in the Company’s Amended and Restated Certificate of Incorporation, and which asked the court in the alternative to stay the Wong action. Also, on August 8, 2018, the venture capital investor and underwriters’ defendants in the Wong action filed demurrers to the Wong complaint, and the Company, along with certain of its current and former executive officers and directors, joined in the venture capital investor defendants’ demurrer. A hearing on the Company’s motion to dismiss and the demurrers to the Wong complaint was held on October 24, 2018. The Company is unable to predict the date on which the Superior Court will issue any decision at this time. On October 2, 2018, the U.S. Northern District Court granted a Motion for Consolidation of Related Actions, Appointment as Lead Plaintiff and Approval of Lead Counsel filed by Plaintiff Edgardo Guerrini, which consolidated the Guerrini and Yzeiraj actions under the caption In re Restoration Robotics, Inc. Securities Litigation, Case No. 5:18-cv-03712-EJD. The U.S. Northern District Court held an initial hearing on January 24, 2019. The Company believes that these lawsuits are without merit and management intends to vigorously defend against these claims.

Long-Term Debt

Long-Term Debt	12 Months Ended
	Dec. 31, 2018
Debt Disclosure [Abstract]
Long-Term Debt	7. LONG-TERM DEBT Loan and Security Agreement with Oxford Finance LLC In May 2015, the Company entered into a loan and security agreement with Oxford Finance, LLC, or Oxford, (the Oxford Agreement). Under the terms of the loan and security agreement, the Company borrowed $20,000 with an interest rate at prime plus 8.5% per annum, which is collateralized by all personal property of the Company excluding intellectual property and issued 10-year warrants to purchase 110,486 shares of Series C Preferred Stock at $7.15 per share. The estimated fair value of the warrants at issuance was recorded as a discount on the loan and amortized into interest expense over the expected life of the loan. In connection with the loan agreement, the Company recorded $246 of credit facility fees and $153 of debt issuance cost as of January 31, 2015. The credit facility fees and debt issuance costs are a discount on the debt and are being amortized to interest expense over the term of the loan using the effective-interest method. The loan will mature in July 2019, at which time the Company must repay the outstanding principal balance which includes a final payment of $1,300. The outstanding principal balance on the loan was $13,300 and accrued interest totaled $85 as of December 31, 2017. The interest rate was 13% at December 31, 2017. In May 2018, the Company used the proceeds from the Solar Agreement to repay the indebtedness of the Oxford Agreement. Borrowings under the Oxford Agreement are collateralized by all the assets of the Company excluding intellectual property. The Oxford Agreement includes customary restrictive covenants that impose operating and financial restrictions on the Company, including restrictions on our ability to take actions that could be in the Company’s best interests. These restrictive covenants include operating covenants restricting, among other things, the Company’s ability to incur additional indebtedness, effect certain acquisitions or make other fundamental changes. The Company was in compliance with all of the covenants as of December 31, 2017. Loan and Security Agreement with Solar Capital Ltd. In May 2018, the Company entered into a Loan and Security Agreement (the Solar Agreement) with Solar Capital Ltd. (Solar) and certain other lenders thereunder (together with Solar, the Lenders), and Solar, as the Collateral Agent. The Solar Agreement consists of a four-year term loan for an aggregate principal amount of $20,000 (the Borrowings), for working capital, to fund the Company’s general business requirements and to repay indebtedness of the Company under the Oxford Agreement. The Company used $10,085 of the loan proceeds to repay the outstanding principal of $8,667, a final payment fee of $1,300 plus accrued interest and prepayment fees of $118 under the Oxford Agreement. The Borrowings under the Solar Agreement bear interest through maturity at a rate equal to the U.S. Dollar LIBOR rate plus 7.95% per annum (the Interest Rate). The outstanding balance on the loan was $20,000 and accrued interest totaled $178 as of December 31, 2018. The Interest Rate was 10.3% at December 31, 2018. Pursuant to the terms of the Solar Agreement, the Company shall make interest only payments until December 1, 2019 (the Interest Only Period). The Interest Only Period may be extended up to three additional months, if the Company achieves certain revenue and capital fundraising thresholds. Following cessation of the Interest Only Period, the Company shall make equal monthly payments on the outstanding principal balance of the Borrowings and any unpaid and accrued interest such that the Borrowings shall be fully repaid on May 1, 2022. In addition, pursuant to the Solar Agreement, the Company issued the Lenders warrants (the Warrants) to purchase an aggregate of 161,725 shares of the Company’s common stock, $0.0001 par value per share, at an exercise price of $3.71 per share. The Warrants were immediately exercisable upon issuance, and excluding certain mergers or acquisitions, will expire on the ten-year anniversary of the date of issuance. The fair value of the Warrants issued was determined to be $404 using a Black-Scholes valuation model with the following assumptions: common stock price at issuance of $3.71 per share; exercise price of $3.71; risk-free interest rate of 2.97% based upon observed risk-free interest rates; expected volatility of 55.50% based on the Company’s implied volatility; expected term of ten years, which is the contractual life of the Warrants; and a dividend yield of 0%. The fair value of the Warrants was recorded as a debt discount within notes payable and an increase to additional paid-in capital on the Company’s balance sheet. The debt discount is being amortized as interest expense over the term of the Solar Agreement, using the effective interest method. The third-party transaction costs (not paid directly to the lenders) related to the debt of $404are accounted for as a debt discount and classified within notes payable on the Company’s balance sheet and amortized as interest expense over the term of the loan using the effective interest method. Unamortized debt discounts related to the Oxford Agreement and all fees paid directly to Solar and Oxford totaling $505 in connection with the debt financing in May 2018 were written off to “Other income (expense), net” in the consolidated statements of operations. The obligations under the Solar Agreement are secured by a lien on substantially all the Company’s property. The Solar Agreement contains certain affirmative covenants, negative covenants and events of default, including, covenants and restrictions that among other things, require the Company and its subsidiary to satisfy certain financial covenants including covenants requiring the Company to satisfy certain revenue and liquidity thresholds, and restricts the ability of the Company and its subsidiary’s ability to, incur liens, incur additional indebtedness, make loans and investments, engage in mergers and acquisitions, engage in asset sales or sale and leaseback transactions, and declare dividends or redeem or repurchase capital stock. A failure to comply with these covenants could permit the Lenders under the Solar Agreement to declare the Borrowings, together with accrued but unpaid interest and certain Prepayment Fees, to be immediately due and payable. On November 2, 2018, the Solar Agreement was amended to modify the compliance requirement for certain revenue and liquidity threshold. As part of this amendment, the Company paid a fee of $50 to the Lenders and cancelled 161,725 Warrants (originally issued in May 2018, as mentioned above) and issued 161,725 new warrants of the Company’s common stock, $0.0001 par value per share, at an exercise price of $1.76 per share. The Warrants were immediately exercisable upon issuance, and excluding certain mergers or acquisitions, will expire on the nine and a half year’ anniversary of the date of issuance. The fair value of the warrants issued, after taking into account the amendment on November 2, 2018, was determined to be $466 using a Black-Scholes valuation model with the following assumptions: common stock price at issuance of $1.96 per share, exercise price of $1.76; risk-free interest rate of 3.22% based upon observed risk-free interest rates, expected volatility of 59.70% based on the Company’s implied volatility; expected term of ten years, which is the contractual life of the Warrants, and a dividend yield of 0%. The fair value of the Warrants was recorded as a debt discount within notes payable and an increase to additional paid-in capital on the Company’s balance sheet. As of December 31, 2018, the Company was in compliance with all covenants under the Solar Agreement, as amended. The Company is also required to make mandatory prepayments of the Borrowings, subject to specified exceptions, upon defaulting on any payments of principal or interest on the Borrowings, the occurrence of certain specified defaults of the covenants in the Solar Agreement, the occurrence of a material adverse change in the business, operations or conditions of the Company and specified other events (each, an Event of Default). Upon the occurrence and continuation of an Event of Default, the Borrowings shall accrue at the Interest Rate plus 4.0%. If all or any of the Borrowings are prepaid or required to be prepaid under the Solar Agreement, then the Company shall pay, in addition to such prepayment, a prepayment premium (the Prepayment Premium) equal to (i) with respect to any such prepayment paid on or prior to May 1, 2019, 3.0% of the principal amount of the Borrowings being prepaid, (ii) with respect to any prepayments paid after May 1, 2019 but on or prior to May 1, 2020, 2.0% of the principal amount of the Borrowings being prepaid and (iii) with respect to any prepayments paid after May 1, 2020 but on or prior to May 1, 2021, 1.0% of the principal amount of the Borrowings being prepaid. Notwithstanding the foregoing, if the Lenders each participate in a refinancing of the Borrowings, then the Prepayment Premium shall be 0%. The scheduled principal payments on the outstanding borrowings as of December 31, 2018 are as follows: As of December 31, 2018 2019 $ 667 2020 8,000 2021 8,000 2022 4,163 Total 20,830 Less: debt discounts and issuance costs (1,363 ) Less: current portion (49 ) Non-current portion $ 19,418 For the year ended December 31, 2018 and 2017, the Company made principal repayments of $13,300 and $8,000.

Common Stock Reserved For Issua

Common Stock Reserved For Issuance	12 Months Ended
	Dec. 31, 2018
Equity [Abstract]
Common Stock Reserved For Issuance	8. COMMON STOCK RESERVED FOR ISSUANCE The Company is required to reserve and keep available out of its authorized but unissued shares of common stock a number of shares sufficient to affect the conversion of all outstanding shares of convertible preferred stock (and preferred stock warrants), plus options granted and available for grant under the incentive plans. December 31, 2018 December 31, 2017 Outstanding common stock warrants 272,211 306,456 Outstanding and issued stock options 3,989,432 1,930,752 Shares reserved for future option grants 437,241 271,490 Total common stock reserved for issuance 4,698,884 2,508,698

Stock Option Plan

Stock Option Plan	12 Months Ended
	Dec. 31, 2018
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Stock Option Plan	9. STOCK OPTION PLAN 2017 Plan The 2017 Equity Incentive Plan (2017 Plan) became effective on October 11, 2017. Under the 2017 Plan, 1,913,831 shares of common stock were initially reserved for the grant of incentive stock options (ISOs), non-statutory stock options (NSOs), stock appreciation rights, restricted stock awards, restricted stock unit awards, and other forms of equity compensation to employees, directors and consultants. In addition, the Company’s 2017 Plan provides for the grant of performance cash awards to employees, directors and consultants. Prior to the 2017 Plan, 306,756 shares that had been available for future awards under 2015 Plan (defined below) as of October 11, 2017, were added to the initial reserve available under 2017 Plan, bringing the total number of shares reserved for issuance under the 2017 Plan upon effective date to 2,220,587 shares. The number of shares reserved for issuance under the 2017 Plan will increase automatically on the first day of each fiscal year beginning in 2018 and ending in 2027, equal to the lesser of (i) 4% of the shares of stock outstanding on the last day of the immediately preceding fiscal year or (ii) number of shares of stock as determined by the Company’s board of directors. 2005 and 2015 Plan The Company granted options under 2015 Equity Incentive Plan (the 2015 Plan) and 2005 Stock Option Plan (the 2005 Plan) until October 2017 when they were terminated as to future awards, although they continue to govern the terms of options that remain outstanding under the 2005 Plan and the 2015 Plan, as the case may be. The 2005 Plan provided for the granting of ISOs and NSOs. In 2015, the Company established its 2015 Plan, which superseded and replaced the 2005 Plan. In connection with the Board of Directors approval of the 2017 Plan, all remaining shares available for future award under the 2015 Plan were transferred to the 2017 Plan, and the 2015 Plan was terminated. The Company recognized stock-based compensation for its employees and non-employees in the accompanying consolidated statements of operations as follows: Year Ended December 31, 2018 2017 2016 Cost of revenue $ 19 $ 10 $ 12 Sales and marketing 149 74 85 Research and development 58 101 102 General and administrative 441 280 267 Total stock-based compensation $ 667 $ 465 $ 466 Stock Options The fair value of each option is estimated at the date of grant using the Black-Scholes option pricing formula with the following assumptions : Year Ended December 31, 2018 2017 2016 Expected term (in years) 5.10-6.10 4.95-7.50 5.53–6.11 Risk-free interest rate 2.40-2.96% 1.77-2.13% 1.30–1.84% Expected volatility 53.72-59.74% 51.62-55.38% 52.71–56.58% Expected dividend rate 0% 0% 0% Expected Term —The expected term represents expected term of the Company’s identified peer group of publicly-traded companies and will continue to apply this methodology until sufficient historical information regarding its own expected term becomes available . Volatility —Since the Company does not have a trading history for its common stock, the expected volatility was derived from the historical stock volatilities of comparable peer public companies within its industry that are considered to be comparable to the Company’s business over a period equivalent to the expected term of the stock-based awards. Risk-Free Interest Rate —The risk-free interest rate is based on the U.S. Treasury yield curve in effect at the date of grant for zero-coupon U.S. Treasury notes with maturities approximately equal to the stock-based awards’ expected term. Dividend Rate —The expected dividend is zero as the Company has not paid nor does it anticipate paying any dividends on its common stock in the foreseeable future. Fair Value of Common Stock —Prior to the closing of the Company’s IPO, the fair value of the Company’s common stock was determined by the Company’s board of directors because there was no public market for the Company’s common stock as the Company was a private company. The Company’s board of directors determined the fair value of the common stock by considering a number of objective and subjective factors, including having valuations of its common stock performed by an unrelated valuation specialist, valuations of comparable peer public companies, sales of the Company’s convertible preferred stock to unrelated third parties, operating and financial performance, the lack of liquidity of the Company’s capital stock, and general and industry-specific economic outlook. After the closing of the Company’s IPO, the fair value of the Company’s common stock is used to estimate the fair value of the stock-based awards at grant date. The following table summarizes stock option activity under the Company’s stock option plan: Number of Shares Weighted- Average Exercise Price per Share Weighted- Average Remaining Contractual Term Aggregate Intrinsic Value Outstanding – December 31, 2015 1,410,708 $ 1.90 7.9 $ — Options granted 1,179,644 1.70 Options exercised (20,218 ) 2.00 Options cancelled (737,377 ) 2.00 Options expired (1,000 ) 0.50 Outstanding – December 31, 2016 1,831,757 1.80 8.7 $ 14 Options granted 192,420 3.12 Options exercised (21,843 ) 2.01 Options cancelled (71,582 ) 1.81 Outstanding – December 31, 2017 1,930,752 1.90 7.9 $ 5,322 Options granted 2,551,707 1.98 Options exercised (236,730 ) 1.66 Options cancelled (256,297 ) 2.03 Outstanding - December 31, 2018 3,989,432 $ 1.95 8.7 $ — Vested and expected to vest – December 31, 2018 3,531,802 $ 1.96 8.6 $ — Exercisable – December 31, 2018 1,187,091 $ 1.82 7.2 $ — The weighted-average grant date fair value of options granted was $1.06, $1.73 and $0.86 per share for years ended December 31, 2018, 2017 and 2016. The total intrinsic value of options exercised were $417, $1.18 and $0 for years ended December 31, 2018, 2017 and 2016. Unamortized stock-based compensation was $2,351 as of December 31, 2018, which is expected to be recognized over a weighted-average period of approximately 3.13 years. Restricted Stock Awards The Company’s Board of Directors appointed Keith Sullivan, a current Board member of the Company, as interim Chief Commercial Officer, effective November 1, 2018, and for a period up to one year. Under the terms of the arrangement, Mr. Sullivan was granted 360,000 restricted stock awards, which shall vest in quarterly installments equal to 25% of the shares starting with the first vest date on January 15, 2019 so long as Mr. Sullivan is providing services. As of December 31, 2018, the Company had $133 of unrecognized compensation expense, net of estimated forfeitures, which it expects to recognize over the next 10 months. The aggregate intrinsic value of the RSAs outstanding was $157.

Income Taxes

Income Taxes	12 Months Ended
	Dec. 31, 2018
Income Tax Disclosure [Abstract]
Income Taxes	10. INCOME TAXES The geographical breakdown of loss before provision for income taxes is as follows: Year Ended December 31, 2018 2017 2016 Domestic $ (28,477 ) $ (17,732 ) $ (21,696 ) Foreign (202 ) (54 ) (150 ) Net loss before provision for income taxes $ (28,679 ) $ (17,786 ) $ (21,846 ) The components of the provision for income taxes are as follows: Year Ended December 31, 2018 2017 2016 Current tax provision: Federal $ — $ — $ — State 9 4 4 Foreign 38 56 16 Total current tax provision 47 60 20 Deferred tax provision (benefit): State — (4 ) (4 ) Foreign — — (16 ) Total deferred tax provision (benefit) $ — $ (4 ) $ (20 ) Total provision for income taxes $ 47 $ 56 $ — Deferred income taxes reflect the net tax effects of temporary differences between the carrying amounts of assets and liabilities for financial reporting purposes and the amounts used for income tax purposes. A valuation allowance is provided when it is more likely than not that the deferred tax assets will not be realized. The Company has established a valuation allowance in the U. S. and Korea to offset net deferred tax assets for all periods presented due to the uncertainty of realizing future tax benefits from net operating loss carryforwards and other deferred tax assets. The valuation allowance increased by $6,156 and decreased by $13,888 for the years ended December 31, 2018 and 2017. The decrease in valuation allowance in 2017 was due to the change in the corporate tax rate from 35% to 21% and the resulting revaluation of the deferred tax assets. On December 22, 2017, the Tax Cuts and Jobs Act (the "Act") was enacted into law making significant changes to the Internal Revenue Code. Changes include, but are not limited to, a federal corporate tax rate decrease from 35% to 21% for tax years beginning after December 31, 2017, the transition of U.S. international taxation from a worldwide tax system to a territorial system and a one-time transition tax on the mandatory deemed repatriation of foreign earnings. ASC 740 requires the Company to recognize the effect of the tax law changes in the period of enactment. However, the SEC staff has issued SAB 118 which will allow the Company to record provisional amounts during the measurement period. In the fourth quarter of 2018, the Company completed its analysis of the impact of U.S. Tax Reform under SAB 118. The amounts originally recorded in the 2017 year-end financial statements were adjusted for the tax rate impact of return to provision adjustments to the Net Operating Loss (“NOL”) carryforward. The tax rates valuing the carryforward changed from 35% to 21%, creating an impact on the ending deferred balances of $21. However, this effect was fully offset by the full valuation allowance, so no additional tax was recognized. The Company’s effective tax rate substantially differed from the federal statutory tax rate primarily due to the change in the valuation allowance. The reconciliation between income taxes computed at the federal statutory income tax rate and the provision for income taxes is as follows: Year Ended December 31, 2018 2017 2016 U.S. federal statutory income tax at 21% for 2018 and 34% for 2017 and 2016, respectively $ (6,022 ) $ (6,046 ) $ (7,306 ) Research tax credits (112 ) (75 ) (99 ) Stock-based compensation 66 85 102 Adjustment of deferred tax balances following changes in tax rates — 20,748 — Other (41 ) 303 117 Change in valuation allowance 6,156 (14,955 ) 7,206 Total current tax provision 47 60 20 Total deferred tax benefit — (4 ) (20 ) Total provision for income taxes $ 47 $ 56 $ — The components of the deferred tax assets are as follows: December 31, 2018 2017 Deferred tax assets: Net operating loss carryforwards $ 42,359 $ 37,173 Research and development credits 3,041 2,823 Accrual and reserves 2,003 1,251 Total deferred tax assets 47,403 41,247 Less: valuation allowance (47,403 ) (41,247 ) Total net deferred tax assets $ — $ — As of December 31, 2018, the Company has federal and state NOL carryforwards of approximately $178,393 and $96,232. The use of these NOL carryforwards might be subject to limitation under the rules regarding a change in stock ownership as determined by the IRC and similar state provisions (the “Code”); however, a complete analysis of the limitation of the NOL carryforwards will not be complete until the time the Company projects it will be able to utilize such NOLs. The NOL carryforwards expire between 2022 and 2038, and valuation allowances have been reserved, where necessary. In addition, as of December 31, 2018, the Company also had NOL carryforwards in South Korea of approximately $1,426 which begin to expire in 2025. The Company also had federal and state research and development credit carryforwards of approximately $1,602 and $1,822, as of December 31, 2018. The federal credit will expire starting in 2025 if not utilized. The state credits have no expiration date. Utilization of the research and development credit carryforwards may be subject to an annual limitation due to the ownership percentage change limitations provided by the Code. However, the Company has not conducted a formal study to determine the extent of the limitations, which could impact the realizability of these credit carryforwards in future periods. The annual limitations may result in the expiration of the net operating losses and research and development credits before utilization. The Company has not provided for U.S. income taxes on undistributed earnings of its foreign subsidiaries because it intends to permanently re-invest these earnings outside the U.S. The cumulative amount of such undistributed earnings upon which no U.S. income taxes have been provided was $443 as of December 31, 2018. These earnings have been subject to U.S. federal income tax via the one-time transition tax on previously undistributed foreign earnings or via the newly enacted Global Intangible Low-Taxed Income (“GILTI”) provision. If these foreign earnings were to be repatriated in the future, the amount of unrecognized deferred tax liability for state income or foreign withholding taxes on these undistributed earnings is not expected to be significant as of December 31, 2018. Uncertain Tax Positions The activity related to the gross amount of unrecognized tax benefits is as follows: Year Ended December 31, 2018 2017 Balance as of the beginning of the year $ 1,362 $ 1,283 Increases related to tax positions in prior period 8 5 Increases related to tax positions taken during the current period 97 74 Balance at the end of the year $ 1,467 $ 1,362 These amounts are related to certain deferred tax assets with a corresponding valuation allowance. If recognized, the impact on the Company’s effective tax rate would not be material due to the full valuation allowance. Management believes that there will not be any significant changes in the Company’s unrecognized tax benefits in the next twelve-months. The Company recognizes interest and penalties related to unrecognized tax benefits in the provision for income taxes in the accompanying consolidated statement of operations. Accrued interest and penalties, if applicable, are included in accrued liabilities in the consolidated balance sheet. For the years ended December 31, 2018, 2017 and 2016, the Company did not recognize any accrued interest and penalties. The Company files income tax returns in the United States and in various state jurisdictions with varying statutes of limitations. Tax years 2002 through 2018 remain open to examination by the United States and various state jurisdictions. The Company is not currently under examination by the Internal Revenue Service or any other jurisdiction for any year.

Segment and Geographic Informat

Segment and Geographic Information	12 Months Ended
	Dec. 31, 2018
Segment Reporting [Abstract]
Segment and Geographic Information	11. SEGMENT AND GEOGRAPHIC INFORMATION Operating segments are defined as components of an entity for which separate financial information is available and that is regularly reviewed by the Chief Operating Decision Maker (CODM) in deciding how to allocate resources to an individual segment and in assessing performance. The Company's CODM is its Chief Executive Officer. The Company has determined it operates in a single operating segment and has one reportable segment, as the CODM reviews financial information presented on a consolidated basis for purposes of making operating decisions, allocating resources, and evaluating financial performance. The Company does not assess the performance of individual product line on measures of profit or loss, or asset-based metrics. Therefore, the information below is presented only for revenues by geography. Revenue by geographic location, which is based on the product shipped to location, is summarized as follows: Year Ended December 31, 2018 2017 2016 United States $ 13,132 $ 8,919 $ 6,736 Europe and Middle East 3,504 5,784 3,112 Asia Pacific 4,007 4,353 3,552 Rest of World 1,313 2,241 2,200 Total revenue $ 21,956 $ 21,297 $ 15,600 As of December 31, 2018, and 2017, all long-term assets were located within the United States.

Selected Quarterly Financial Da

Selected Quarterly Financial Data	12 Months Ended
	Dec. 31, 2018
Quarterly Financial Data [Abstract]
Selected Quarterly Financial Data	12. SELECTED QUARTERLY FINANCIAL DATA The following tables present certain selected unaudited consolidated quarterly financial information for each of the eight quarters ended December 31, 2018. This consolidated quarterly information has been prepared on the same basis as the consolidated financial statements and includes all adjustments necessary to state fairly the information for the periods presented. The selected consolidated quarterly financial results from operations for the years ended December 31, 2018 and 2017 are set forth therein. Net loss per share for all periods presented has been retroactively adjusted to reflect the 1-for-10 reverse stock split effected on September 15, 2017. Fiscal 2018 Quarter Ended, March 31, 2018 Unaudited June 30, 2018 Unaudited September 30, 2018 Unaudited December 31, 2018 Unaudited Revenue, net $ 5,005 $ 5,475 $ 4,818 $ 6,658 Gross profit $ 1,820 $ 2,961 $ 2,155 $ 2,570 Net loss $ (7,431 ) $ (6,244 ) $ (7,070 ) $ (7,981 ) Basic and diluted net loss per share $ (0.26 ) $ (0.21 ) $ (0.20 ) $ (0.20 ) Fiscal 2017 Quarter Ended, March 31, 2017 Unaudited June 30, 2017 Unaudited September 30, 2017 Unaudited December 31, 2017 Unaudited Revenue, net $ 5,475 $ 5,789 $ 4,177 $ 5,856 Gross profit $ 2,383 $ 2,302 $ 1,703 $ 2,759 Net loss $ (5,175 ) $ (5,007 ) $ (6,596 ) $ (1,064 ) Basic and diluted net loss per share $ (3.20 ) $ (3.09 ) $ (4.07 ) $ (0.04 )

Related Party Transactions

Related Party Transactions	12 Months Ended
	Dec. 31, 2018
Related Party Transactions [Abstract]
Related Party Transactions	13. RELATED PARTY TRANSACTIONS During the year ended December 31, 2018, the Company did not engage in any related party transactions. During the year ended December 31, 2017, the Company had engaged in a commercial transaction with a then-member of the Company’s board of directors. The aggregate revenue for this transaction was $83 for the year ended December 31, 2017. There were no accounts receivable due from this then-member of the board of directors as of December 31, 2017. In January 2017, that member of the Company’s board of directors resigned.

Subsequent Event (Unaudited)

Subsequent Event (Unaudited)	12 Months Ended
	Dec. 31, 2018
Subsequent Events [Abstract]
Subsequent Event (Unaudited)	14. SUBSEQUENT EVENT (unaudited) Amendment to Solar Loan On February 13, 2019, the Company entered into a Third Amendment to the Loan and Security Agreement (the “Third Amendment”), which amended the Solar Agreement with the Lenders. Pursuant to the terms of the Third Amendment, the Solar Agreement was amended to modify the compliance requirement for certain liquidity thresholds to provide the Company with additional flexibility. As part of the Third Amendment, the Final Fee (as defined in the Solar Agreement) that is payable to the Lenders upon prepayment, default and maturity of the Solar Agreement, was amended and increased to $960. In addition, the Solar Agreement was amended to include certain additional changes to covenants covering certain operational milestones. Issuance of Convertible Promissory Notes On February 28, 2019, the Company entered into a Note Purchase Agreement pursuant to which the Company raised $5.0 million through the issuance of two unsecured subordinated convertible promissory notes (the “Notes”) to Frederic Moll, M.D., one of the Company’s directors, and Interwest Partners IX, LP, one of the Company’s stockholders affiliated with Gil Kliman, M.D., one of the Company’s directors (together, the “Investors”). The maturity date of the Notes is August 28, 2020 (the “Maturity Date”). The Notes bear interest on the unpaid principal amount at a rate of eight percent (8.0%) per annum from the date of issuance. The Notes are unsecured and subordinate in priority to the Company’s existing obligations under the Solar Agreement, as amended. All of the outstanding principal and unpaid accrued interest on the Notes will automatically be converted into shares of the same class and series of capital stock of the Company issued to other investors in any Qualified Financing to occur after the date of the Notes, at a conversion price equal to the price per share of the securities of the Company sold in such Qualified Financing. A “Qualified Financing” means the first issuance or series of related issuances of capital stock of the Company after the date of the Notes with gross proceeds to the Company of at least $20.0 million. Upon the occurrence of certain events of default or the Maturity Date, the Notes require the Company to repay the principal amount of the Notes and any unpaid accrued interest. Proposed Merger with Venus On March 15, 2019, the Company entered into the Merger Agreement with Venus to combine the companies in an all-stock transaction. The Merger Agreement and the Merger (as defined below) have been approved by the Company’s board of directors and the board of directors of Venus. The transaction is expected to close in the third quarter of 2019, subject to customary closing conditions, including the approval by stockholders of the Company and Venus and receipt of all necessary regulatory approvals. The Merger Agreement provides that, upon the terms and subject to the satisfaction or waiver of the conditions set forth therein, Merger Sub will be merged with and into Venus, with Venus continuing as the surviving corporation and a direct wholly-owned subsidiary of the Company. Under the terms of the transaction, the Company and Venus shareholders will own approximately 15% and 85% of the combined company, respectively, on a fully diluted basis, without giving effect to the shares issued in the proposed equity financing that is expected to close immediately after the merger. EW Healthcare Partners has committed to lead a $21.0 million equity investment, priced at $0.825 per share (subject to adjustment for stock splits), in the combined company’s common stock contingent on the closing of the merger transaction. Additional investors committed to participating in the proposed equity financing include HealthQuest Capital, Madryn Asset Management, Longitude Capital Management, Fred Moll and Aperture Venture Partners. In addition to the equity financing, Fred Moll and InterWest Partners previously funded a $5.0 million convertible note into the Company, which will convert into the combined company’s common stock at the closing of the equity financing led by EW Healthcare, at a price of $0.825 per share (subject to adjustment for stock splits). Concurrent with closing of the transaction, the Company anticipates effecting a reverse stock split. The Company expects to have approximately 283.2 million shares outstanding (or approximately 18.9 million shares outstanding after giving effect to an anticipated 1-for-15 reverse stock split) and after taking into account shares issued to the former Venus Concept shareholders in the merger, shares issued as part of the $21.0 million equity investment, and shares issued upon conversion of the $5.0 million convertible notes issued by the Company in February, 2019, as discussed above.

Summary of Significant Accoun_2

Summary of Significant Accounting Policies (Policies)	12 Months Ended
	Dec. 31, 2018
Accounting Policies [Abstract]
Liquidity	Liquidity These consolidated financial statements are prepared on a going concern basis that contemplates the realization of assets and extinguishment of liabilities in the normal course of business. The Company has incurred net operating losses and negative cash flows from operations since inception. As of December 31, 2018, and 2017, the Company has an accumulated deficit of $193,213 and $164,487 and, as of such dates, did not have sufficient capital to fund its planned operations. As a result of the Company’s recurring losses from operations and negative cash flows, the Company’s independent registered public accounting firm included an explanatory paragraph in its current report on the Company’s consolidated financial statements that such factors raise substantial doubt about the Company’s ability to continue as a going concern. Management plans to manage expenses and obtain additional funds through a combination of equity and debt financing. The Company will need to raise further capital in the future to service its debt and fund its operations until the time it can sustain positive cash flows. There can be no assurance that the Company will be successful in raising additional capital or that such capital, if available, will be on terms that are acceptable to the Company. If the Company is unable to raise sufficient additional capital, it may be compelled to reduce the scope of its operations and planned capital expenditures or sell certain assets, including intellectual property assets. The accompanying consolidated financial statements have been prepared on a going concern basis, which contemplates the realization of assets and the satisfaction of liabilities in the normal course of business, and, as such, the consolidated financial statements do not include any adjustments relating to the recoverability and classification of recorded asset amounts or amounts and classification of liabilities that might be necessary should the Company be unable to continue in existence.
Basis of Presentation	Basis of Presentation The accompanying consolidated financial statements have been prepared in accordance with generally accepted accounting principles in the United States of America (U.S. GAAP). The accompanying consolidated financial statements include the accounts of Restoration Robotics, Inc. and its wholly owned subsidiaries.
Principles of Consolidation	Principles of Consolidation The accompanying consolidated financial statements include the accounts of Restoration Robotics, Inc. and its wholly owned subsidiaries, which are located in the United States, United Kingdom, Spain, Hong Kong and South Korea. All significant intercompany accounts and transactions have been eliminated in consolidation.
Reclassification	Reclassification Accrued compensation, which was previously included in other accrued liabilities in the prior year's consolidated balance sheet has been reclassified to conform to the current period's presentation. The reclassification had no impact on the previously reported consolidated balance sheet for the year ended December 31, 2017. The provision for bad debt, which was previously included in accounts receivable in the prior year’s consolidated statements of cash flow has been reclassified to conform to the current period’s presentation. The reclassification had no impact on the previously reported consolidated statements of cash flow for the year ended December 31, 2017.
Use of Estimates	Use of Estimates The preparation of the consolidated financial statements in conformity with U.S. GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities as of the date of the consolidated financial statements and the reported amounts of revenue and expenses during the reporting period. Significant estimates and assumptions made in the accompanying consolidated financial statements include, but are not limited to revenue recognition, allowance for doubtful accounts, inventory valuation, stock-based compensation, warranty accrual and the recoverability of the Company’s net deferred tax assets. The Company evaluates its estimates and assumptions on an ongoing basis using historical experience and other factors and adjusts those estimates and assumptions when facts and circumstances dictate. Actual results could materially differ from those estimates.
Foreign Currency	Foreign Currency The functional currency of the Company’s non-U.S. subsidiaries is the local currency. Asset and liability balances denominated in non-U.S. dollar currencies are translated into U.S. dollars using period-end exchange rates, while revenue and expenses are based upon the exchange rate at the time of the transaction, if known, or at the average rate for the period. Differences are included in stockholders’ equity (deficit) as a component of accumulated other comprehensive loss. Financial assets and liabilities denominated in currencies other than the functional currency are recorded at the exchange rate at the time of the transaction and subsequent gains and losses related to changes in the foreign currency are included in other income (expense), net in the accompanying consolidated statements of operations. The net foreign transaction gain or losses were insignificant for all periods presented.
Cash and Cash Equivalents	Cash and Cash Equivalents The Company considers all highly liquid investments with an original maturity of three months or less from the date of purchase to be cash equivalents. Cash and cash equivalents consist primarily of funds invested in readily available checking and savings accounts, investments in money market funds and short-term time deposits.
Restricted Cash	Restricted Cash As of December 31, 2018, and 2017, the Company was required to hold $83 and $100, respectively, in a separate money market account as collateral for credit cards.
Concentration of Credit Risk	Concentration of Credit Risk Financial instruments that potentially subject the Company to a concentration of credit risk consist of cash and cash equivalents, restricted cash and accounts receivable. Substantially all of the Company’s cash and cash equivalents and restricted cash are held with two financial institutions, and the account balances exceed the Federal Deposit Insurance Corporation (FDIC) insurance limit. Accounts are insured by the FDIC up to $250 per financial institution. The Company has not experienced any losses in such accounts with these financial institutions.
Concentration of Customers	Concentration of Customers For the years ended December 31, 2018, 2017 and 2016, there were no customers accounting for more than 10% of the Company’s revenue. As of December 31, 2018, there were no customers accounting for more than 10% of the Company’s accounts receivable. As of December 31, 2017, two customers each accounted for 10% and 11% of the Company’s accounts receivable.
Allowance for Doubtful Accounts	Allowance for Doubtful Accounts Accounts receivable do not bear interest and are typically not collateralized. The Company performs ongoing credit evaluations of its customers’ financial condition and maintains an allowance for doubtful accounts. Uncollectible accounts are charged to expense when deemed uncollectible, and accounts receivable are presented net of an allowance for doubtful accounts. Accounts receivable are deemed past due in accordance with the contractual terms of the agreement. Actual The allowance for doubtful accounts consisted of the following activity for years ended December 31, 2018 and 2017 (in thousands): As of December 31, 2018 2017 Balance at Beginning of Year $ 229 $ — Charge to expense 1,772 229 Write-offs, net of recoveries (229 ) — Balance at End of Year $ 1,772 $ 229
Inventory	Inventory Inventory is stated at the lower of cost or net realizable value and cost is principally determined using the first-in, first-out method. Costs include material, labor and overhead. Inventory that is obsolete or in excess of forecasted usage is written down to its estimated net realizable value based on assumptions about future demand and market conditions. Inventory write-downs are charged to cost of goods sold and a new cost basis for the inventory is established.
Property and Equipment	Property and Equipment Property and equipment are stated at cost, net of accumulated depreciation and amortization. Depreciation and amortization are computed using the straight-line method over the estimated useful lives of the assets, which is between three and five years. Leasehold improvements are amortized over the lesser of the life of the lease or the useful life of the improvements. Maintenance and repairs are charged to expense as incurred. When assets are retired or otherwise disposed of, the cost and accumulated depreciation are removed from the consolidated balance sheet, and any resulting gain or loss is reflected in operations.
Impairment of Long-Lived Assets	Impairment of Long-Lived Assets Property and equipment are reviewed annually for impairment or whenever events or changes in circumstances indicate that the carrying amount of an asset may not be recoverable. Recoverability is measured by comparison of the carrying amount to the future net undiscounted cash flows that the assets are expected to generate. If the carrying amount of an asset group exceeds its estimated future cash flows, an impairment charge is recognized in the amount by which the carrying amount of the asset group exceeds the fair value of the asset group. If such assets are considered to be impaired, the impairment to be recognized is measured by the amount by which the carrying amount of the assets exceeds the projected discounted future net cash flows arising from the asset. There has been no impairment of long-lived assets for any of the periods presented.
Debt Issuance Costs	Debt Issuance Costs Costs related to the issuance of debt are presented as a direct deduction to the carrying value of the debt and are amortized to interest expense using the effective interest rate method over the term of the related debt.
Gain on Sale of Stock Investment	Gain on Sale of Stock Investment In the fourth quarter of 2017, the Company recognized a gain of $1,851 on the sale of stock held in a privately-held company that had been impaired and written-down to nil prior to fiscal year 2014.
Revenue Recognition	Revenue Recognition The Company generates revenue from sales of robotic systems and related procedures, and related support and maintenance. The Company derives revenue primarily from two sources: (i) Product revenue, which consist of the sale of the ARTAS System, procedure kits, upgrades and training; and (ii) Support and maintenance revenue, which primarily consist of our ARTAS Care (i.e. extended warranty service contracts). Revenue is recognized when all of the following criteria are met: (l) persuasive evidence of an arrangement exists; (2) the product or service has been delivered; (3) the sales price is fixed or determinable; and (4) collection is reasonably assured. The Company defines each of the four criteria above as follows: • Persuasive Evidence of Arrangement Exists . The Company uses purchase orders pursuant to the terms and conditions of a master agreement to support the evidence of an arrangement with distributors and uses purchase agreements as evidence of arrangement with direct customers. • Delivery has Occurred . Provided that all other revenue recognition criteria have been met the Company typically recognizes system revenue upon shipment for systems as title and risk of loss are transferred at that time, and there are no further obligations and no rights of return. Prior to January 1, 2018, the Company typically recognized system revenue upon customer acceptance for sales to direct customers. This change in accounting was as a result of a change in business process, which included the shipment of fully assembled systems starting in 2018. Procedure revenue is recognized upon shipment of disposable kits and delivery of the ARTAS key, if applicable. ARTAS Care (extended warranty contracts) are recognized over time as the services are delivered. • The Sales Price is Fixed or Determinable . The Company assesses whether the fee is fixed or determinable based on the payment terms associated with the transaction. If the terms are extended beyond the Company’s normal payment terms, the Company will recognize revenue as the payments become due. Payments from distributors are not contingent on the distributors’ receiving payment from the end-users. • Collection is Reasonably Assured . The Company assesses probability of collection on an individual basis based on a number of factors, including the credit-worthiness of the customer and past transaction history with the customer. The Company generally obtains a significant cash deposit from its customers prior to shipment. The Company records its revenue net of sales tax and shipping and handling costs. Incremental direct costs incurred related to the acquisition or origination of a customer contract are expensed as incurred. Multiple Element Arrangements The Company’s offering includes robotic systems containing software components that function together to provide the essential functionality of the product. Therefore, the Company’s hardware products (inclusive of the core software) are considered non-software deliverables and are not subject to industry-specific software revenue recognition guidance. The Company’s typical multiple element arrangement generally includes robotic systems (including the essential software), procedure key, product training, and procedure kits. The Company considers each of these deliverables to be separate units of accounting based on whether the delivered items have stand-alone value. The Company has determined that each unit of accounting has stand-alone value because they are sold separately by the Company or, for hardware products, because the customers can resell them to others on a stand-alone basis. For the arrangements with multiple deliverables, the Company allocates the arrangement fee to each element based upon the relative selling price of such element. When applying the relative selling price method, the Company determines the selling price for each element using vendor-specific objective evidence (VSOE) of selling price, if it exists, or if not, third-party evidence (TPE) of selling price, if it exists. If neither VSOE nor TPE of selling price exist for an element, the Company uses its best estimated selling price (BESP) for that element. The revenue allocated to each element is then recognized when the basic revenue recognition criteria are met for that element. The Company is not able to establish a selling price of its deliverables using VSOE or to determine TPE for its products and services. TPE is determined based on competitor prices for similar deliverables when sold separately. Generally, the Company’s go-to-market strategy differs from that of its peers and its offerings contain a significant level of differentiation such that the comparable pricing of products with similar functionality cannot be obtained. When the Company is unable to establish the selling price of its deliverables using VSOE or TPE, the Company uses BESP in its allocation of arrangement consideration. The objective of BESP is to determine the price at which the Company would transact a sale if the product or service were sold on a stand-alone basis. The Company determines BESP for a product or service by considering multiple factors including, but not limited to, industry and market conditions, competitive landscape, standard pricing practices and internal cost models. Additionally, the Company considers historical transactions, including transactions whereby the deliverable was sold on a stand-alone basis. Deferred revenue primarily relates to ARTAS Care (extended warranty) and training not yet provided to our customers. The current portion of deferred revenue represents the amounts that are expected to be recognized as revenue within one year of the consolidated balance sheet date.
Cost of Revenue	Cost of Revenue Cost of revenue consists of product and fulfillment costs. Product costs include the cost of systems and disposable kits manufacture, related labor and personnel costs and allocated shared costs. Fulfillment costs consist of costs incurred in the shipping and handling of inventory including the shipping costs to the Company's customers, labor and related personnel costs related to receiving, inspecting, warehousing, and preparing systems and reusable kits for shipment. Cost of revenue for customer service is expensed as incurred and primarily consists of personnel costs and related benefits for employees associated with service contracts, travel costs and allocated shared costs (including rent and information technology).
Advertising Costs	Advertising Costs The cost of advertising and media is expensed as incurred. For the years ended December 31, 2018, 2017 and 2016, advertising costs totaled $297, $99 and $130, respectively.
Research and Development	Research and Development Research and development costs are charged to operations as incurred. Major components of research and development expenses consist of personnel costs, including salaries and benefits, hardware and software research and development costs, regulatory affairs, and clinical costs.
Warranty	Warranty The Company provides a one-year warranty on the ARTAS ®
Income Taxes	Income Taxes Income taxes are accounted for under the asset and liability method. Deferred tax assets and liabilities are recognized for the future tax consequences attributable to differences between the tax and financial reporting bases of the Company’s assets and liabilities. Deferred tax assets and liabilities are measured using enacted tax rates expected to apply to taxable income in future years in which those temporary differences are expected to be recovered or settled. Deferred tax assets are reduced through the establishment of a valuation allowance, if, based upon available evidence, it is determined that it is more likely than not that the deferred tax assets will not be realized. All deferred tax assets and liabilities are classified as non-current in the consolidated financial statements. Uncertain Tax Positions The Company recognizes the effect of income tax positions only if those positions are more likely than not of being sustained on examination based on the technical merit of the position. The first step is to evaluate the tax position for recognition by determining if the weight of available evidence indicates it is more likely than not that the position will be sustained on examination, including resolution of related appeals or litigation processes, if any. The second step is to measure the tax benefit as the largest amount, which is more than 50% likely of being realized upon ultimate settlement. The Company considers many factors when evaluating and estimating its tax positions and tax benefits, which may require periodic adjustments. The Company recognizes interest charges and penalties related to unrecognized tax benefits as a component of the tax provision.
Stock-Based Compensation	Stock-Based Compensation The Company accounts for share-based compensation costs in accordance with the accounting standards for share-based compensation, which require that all share-based payments to employees be recognized in the consolidated statements of operations based on their fair values. • The fair value of stock options ("options") on the grant date is estimated using the Black-Scholes option-pricing model using the single-option approach. The Black-Scholes option pricing model requires the use of highly subjective and complex assumptions, including the option's expected term and the price volatility of the underlying stock, to determine the fair value of award. The Company recognizes the expense associated with options using a single-award approach over the requisite service period. • The fair value of Restricted Stock Awards ("RSAs") is based on the stock price on the grant date using a single-award approach. RSAs granted to non-employees are re-measured at the end of each reporting period based on the stock price on the last business day of the reporting period. The RSAs are subject to a service vesting condition and are recognized on a straight-line basis over the requisite service period, adjusted for any re-measurement changes at the end of each reporting period. No RSAs have been granted to employees. The Company recognizes share-based compensation expense for the portion of the equity award that is expected to vest over the requisite service period for those awards and develops an estimate of the number of share-based awards which will ultimately vest, primarily based on historical experience. The estimated forfeiture rate is reassessed periodically throughout the requisite service period. Such estimates are revised if they differ materially from actual forfeitures. As required, the forfeiture estimates will be adjusted to reflect actual forfeitures when an award vests. For the award types discussed above, if an employee terminates employment prior to being vested in an award, then the award is forfeited.
Net Loss Per Share	Net Loss Per Share Prior to the conversion of all the preferred stock in connection with the IPO, the Company followed a two‑class method when computing net loss per common share as we issue shares that meet the definition of participating securities. The two‑class method determines net income (loss) per common share for each class of common stock and participating securities according to dividends declared or accumulated and participation rights in undistributed earnings. The two‑class method requires income for the period to be allocated between common stock and participating securities based upon their respective rights to receive dividends as if all income for the period had been distributed. The Company’s convertible preferred stock contractually entitles the holders of such shares to participate in dividends but does not contractually require the holders of such shares to participate in the Company’s losses. For periods in which the Company has reported net losses, diluted net loss per common share attributable to common stockholders is the same as basic net loss per common share attributable to common stockholders, because potentially dilutive common shares are not assumed to have been issued if their effect is anti‑dilutive.
Defined Contribution Plan	Defined Contribution Plan The Company offers a defined contribution retirement savings plan under Section 401(k) of the Internal Revenue Code (IRC). This plan covers employees who meet minimum age and service requirements and allows participants to defer a portion of their annual compensation on a pre-tax basis. Company contributions to the plan may be made at the discretion of the Board of Directors. There were no contributions by the Company during the years ended December 31, 2018, 2017 and 2016.
Jobs Act Accounting Election	JOBS Act Accounting Election The Company is an emerging growth company, as defined in the Jumpstart Our Business Startups Act of 2012, or the JOBS Act. Under the JOBS Act, emerging growth companies can delay adopting new or revised accounting standards issued subsequent to the enactment of the JOBS Act until such time as those standards apply to private companies. The Company has elected to use this extended transition period for complying with new or revised accounting standards that have different effective dates for public and private companies until the earlier of the date that it is (i) no longer an emerging growth company or (ii) affirmatively and irrevocably opt out of the extended transition period provided in the JOBS Act. As a result, these consolidated financial statements may not be comparable to companies that comply with the new or revised accounting pronouncements as of public company effective dates.
Recently Issued Accounting Standards Not Yet Adopted	Recently Issued Accounting Standards Not Yet Adopted In May 2014, the Financial Accounting Standards Board (FASB) issued ASU No. 2014‑09, Revenue from Contracts with Customers (Topic 606) In February 2016, the FASB issued ASU No. 2016‑02, Leases (Topic 842) In June 2018, the FASB issued ASU No. 2018-7, Compensation – Stock Compensation (Topic 718)— Improvements to Nonemployee Share-Based Payment Accounting

Summary of Significant Accoun_3

Summary of Significant Accounting Policies (Tables)	12 Months Ended
	Dec. 31, 2018
Accounting Policies [Abstract]
Summary of Allowance for Doubtful Accounts	The allowance for doubtful accounts consisted of the following activity for years ended December 31, 2018 and 2017 (in thousands): As of December 31, 2018 2017 Balance at Beginning of Year $ 229 $ — Charge to expense 1,772 229 Write-offs, net of recoveries (229 ) — Balance at End of Year $ 1,772 $ 229

Net Loss Per Share (Tables)

Net Loss Per Share (Tables)	12 Months Ended
	Dec. 31, 2018
Earnings Per Share [Abstract]
Outstanding Shares of Common Stock Equivalents Excluded from Calculation of Diluted Net Loss per Share Attributable to Common Stockholders	Due to the net loss, all the outstanding shares of common stock equivalents were excluded from the calculation of diluted net loss per share attributable to common stockholders for the periods presented because including them would have been antidilutive: As of December 31, 2018 2017 2016 Options to purchase common stock 3,989,432 1,930,752 1,831,757 Convertible preferred stock — — 21,142,295 Warrants for preferred stock — — 385,126 Warrants for common stock 272,211 306,456 — Total potential dilutive shares 4,261,643 2,237,208 23,359,178

Fair Value Measurements - (Tabl

Fair Value Measurements - (Tables)	12 Months Ended
	Dec. 31, 2018
Fair Value Disclosures [Abstract]
Schedule for Fair Value of Financial Assets and Liabilities by Level within Fair Value Hierarchy	The following tables set forth the fair value of the Company’s financial assets and liabilities by level within the fair value hierarchy: Fair Value Measurements as of December 31, 2018 Quoted Prices in Active Markets using Identical Assets (Level 1) Significant Other Observable Inputs (Level 2) Significant Unobservable Inputs (Level 3) Total Assets Cash Equivalents: Money market account $ 13,968 $ — $ — $ 13,968 Restricted cash: Money market account 83 83 Total assets $ 14,051 $ — $ — $ 14,051 Fair Value Measurements as of December 31, 2017 Quoted Prices in Active Markets using Identical Assets (Level 1) Significant Other Observable Inputs (Level 2) Significant Unobservable Inputs (Level 3) Total Assets Cash Equivalents: (1) Money market account $ 18,728 $ — $ — $ 18,728 Restricted cash: Money market account 100 — — 100 Total assets $ 18,828 $ — $ — $ 18,828 (1) The Company incorrectly overstated its cash equivalents by $4,817 in the fair value measurements footnote of its annual report on Form 10-K for

Balance Sheet Components (Table

Balance Sheet Components (Tables)	12 Months Ended
	Dec. 31, 2018
Balance Sheet Components [Abstract]
Schedule of Inventory	Inventory December 31, 2018 2017 Raw materials $ 2,464 $ — Work-in-process 323 — Finished goods 2,735 2,761 Total inventory $ 5,522 $ 2,761
Schedule of Property and Equipment, Net	Property December 31, 2018 2017 Computer hardware and software $ 901 $ 721 Equipment 3,531 2,929 Leasehold improvements 874 869 Furniture and fixtures 457 270 Total property and equipment 5,763 4,789 Less: Accumulated depreciation and amortization (4,464 ) (3,651 ) Total property and equipment, net $ 1,299 $ 1,138

Commitments and Contingencies (

Commitments and Contingencies (Tables)	12 Months Ended
	Dec. 31, 2018
Commitments And Contingencies Disclosure [Abstract]
Summary of Aggregate Future Minimum Lease Payments under Operating Leases	Aggregate future minimum lease payments required under the Company’s operating leases as of December 31, 2018 are as follows: Years ending December 31, 2019 $ 518 2020 534 2021 550 2022 188 Thereafter — Total future minimum lease payments $ 1,790

Long-Term Debt (Tables)

Long-Term Debt (Tables)	12 Months Ended
	Dec. 31, 2018
Debt Disclosure [Abstract]
Schedule Principal Payments on Outstanding Borrowings	The scheduled principal payments on the outstanding borrowings as of December 31, 2018 are as follows: As of December 31, 2018 2019 $ 667 2020 8,000 2021 8,000 2022 4,163 Total 20,830 Less: debt discounts and issuance costs (1,363 ) Less: current portion (49 ) Non-current portion $ 19,418

Common Stock Reserved For Iss_2

Common Stock Reserved For Issuance (Tables)	12 Months Ended
	Dec. 31, 2018
Equity [Abstract]
Schedule of Common Stock Reserved for Issuance	The Company is required to reserve and keep available out of its authorized but unissued shares of common stock a number of shares sufficient to affect the conversion of all outstanding shares of convertible preferred stock (and preferred stock warrants), plus options granted and available for grant under the incentive plans. December 31, 2018 December 31, 2017 Outstanding common stock warrants 272,211 306,456 Outstanding and issued stock options 3,989,432 1,930,752 Shares reserved for future option grants 437,241 271,490 Total common stock reserved for issuance 4,698,884 2,508,698

Stock Option Plan (Tables)

Stock Option Plan (Tables)	12 Months Ended
	Dec. 31, 2018
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Summary of Recognized Stock-based Compensation Expense for Employees and Non-employees	The Company recognized stock-based compensation for its employees and non-employees in the accompanying consolidated statements of operations as follows: Year Ended December 31, 2018 2017 2016 Cost of revenue $ 19 $ 10 $ 12 Sales and marketing 149 74 85 Research and development 58 101 102 General and administrative 441 280 267 Total stock-based compensation $ 667 $ 465 $ 466
Assumptions used in Fair Value of Option Estimated at Date of Grant using Black-Scholes Option Pricing Formula	The fair value of each option is estimated at the date of grant using the Black-Scholes option pricing formula with the following assumptions : Year Ended December 31, 2018 2017 2016 Expected term (in years) 5.10-6.10 4.95-7.50 5.53–6.11 Risk-free interest rate 2.40-2.96% 1.77-2.13% 1.30–1.84% Expected volatility 53.72-59.74% 51.62-55.38% 52.71–56.58% Expected dividend rate 0% 0% 0%
Summary of Stock Option Activity	The following table summarizes stock option activity under the Company’s stock option plan: Number of Shares Weighted- Average Exercise Price per Share Weighted- Average Remaining Contractual Term Aggregate Intrinsic Value Outstanding – December 31, 2015 1,410,708 $ 1.90 7.9 $ — Options granted 1,179,644 1.70 Options exercised (20,218 ) 2.00 Options cancelled (737,377 ) 2.00 Options expired (1,000 ) 0.50 Outstanding – December 31, 2016 1,831,757 1.80 8.7 $ 14 Options granted 192,420 3.12 Options exercised (21,843 ) 2.01 Options cancelled (71,582 ) 1.81 Outstanding – December 31, 2017 1,930,752 1.90 7.9 $ 5,322 Options granted 2,551,707 1.98 Options exercised (236,730 ) 1.66 Options cancelled (256,297 ) 2.03 Outstanding - December 31, 2018 3,989,432 $ 1.95 8.7 $ — Vested and expected to vest – December 31, 2018 3,531,802 $ 1.96 8.6 $ — Exercisable – December 31, 2018 1,187,091 $ 1.82 7.2 $ —

Income Taxes (Tables)

Income Taxes (Tables)	12 Months Ended
	Dec. 31, 2018
Income Tax Disclosure [Abstract]
Schedule of Geographical Breakdown of Loss Before Provision for Income Taxes	The geographical breakdown of loss before provision for income taxes is as follows: Year Ended December 31, 2018 2017 2016 Domestic $ (28,477 ) $ (17,732 ) $ (21,696 ) Foreign (202 ) (54 ) (150 ) Net loss before provision for income taxes $ (28,679 ) $ (17,786 ) $ (21,846 )
Schedule of Components of Provision for Income Taxes	The components of the provision for income taxes are as follows: Year Ended December 31, 2018 2017 2016 Current tax provision: Federal $ — $ — $ — State 9 4 4 Foreign 38 56 16 Total current tax provision 47 60 20 Deferred tax provision (benefit): State — (4 ) (4 ) Foreign — — (16 ) Total deferred tax provision (benefit) $ — $ (4 ) $ (20 ) Total provision for income taxes $ 47 $ 56 $ —
Reconciliation between Income Taxes Computed at Federal Statutory Income Tax Rate and Provision for Income Taxes	The reconciliation between income taxes computed at the federal statutory income tax rate and the provision for income taxes is as follows Year Ended December 31, 2018 2017 2016 U.S. federal statutory income tax at 21% for 2018 and 34% for 2017 and 2016, respectively $ (6,022 ) $ (6,046 ) $ (7,306 ) Research tax credits (112 ) (75 ) (99 ) Stock-based compensation 66 85 102 Adjustment of deferred tax balances following changes in tax rates — 20,748 — Other (41 ) 303 117 Change in valuation allowance 6,156 (14,955 ) 7,206 Total current tax provision 47 60 20 Total deferred tax benefit — (4 ) (20 ) Total provision for income taxes $ 47 $ 56 $ —
Schedule of Components of Deferred Tax Assets	The components of the deferred tax assets are as follows: December 31, 2018 2017 Deferred tax assets: Net operating loss carryforwards $ 42,359 $ 37,173 Research and development credits 3,041 2,823 Accrual and reserves 2,003 1,251 Total deferred tax assets 47,403 41,247 Less: valuation allowance (47,403 ) (41,247 ) Total net deferred tax assets $ — $ —
Schedule of Reconciliation of Uncertain Tax Position	The activity related to the gross amount of unrecognized tax benefits is as follows: Year Ended December 31, 2018 2017 Balance as of the beginning of the year $ 1,362 $ 1,283 Increases related to tax positions in prior period 8 5 Increases related to tax positions taken during the current period 97 74 Balance at the end of the year $ 1,467 $ 1,362

Segment and Geographic Inform_2

Segment and Geographic Information (Tables)	12 Months Ended
	Dec. 31, 2018
Segment Reporting [Abstract]
Schedule of Revenue by Geographic Area	Revenue by geographic location, which is based on the product shipped to location, is summarized as follows: Year Ended December 31, 2018 2017 2016 United States $ 13,132 $ 8,919 $ 6,736 Europe and Middle East 3,504 5,784 3,112 Asia Pacific 4,007 4,353 3,552 Rest of World 1,313 2,241 2,200 Total revenue $ 21,956 $ 21,297 $ 15,600

Selected Quarterly Financial _2

Selected Quarterly Financial Data (Tables)	12 Months Ended
	Dec. 31, 2018
Quarterly Financial Data [Abstract]
Schedule of Selected Quarterly Financial Data	The following tables present certain selected unaudited consolidated quarterly financial information for each of the eight quarters ended December 31, 2018. This consolidated quarterly information has been prepared on the same basis as the consolidated financial statements and includes all adjustments necessary to state fairly the information for the periods presented. The selected consolidated quarterly financial results from operations for the years ended December 31, 2018 and 2017 are set forth therein. Net loss per share for all periods presented has been retroactively adjusted to reflect the 1-for-10 reverse stock split effected on September 15, 2017. Fiscal 2018 Quarter Ended, March 31, 2018 Unaudited June 30, 2018 Unaudited September 30, 2018 Unaudited December 31, 2018 Unaudited Revenue, net $ 5,005 $ 5,475 $ 4,818 $ 6,658 Gross profit $ 1,820 $ 2,961 $ 2,155 $ 2,570 Net loss $ (7,431 ) $ (6,244 ) $ (7,070 ) $ (7,981 ) Basic and diluted net loss per share $ (0.26 ) $ (0.21 ) $ (0.20 ) $ (0.20 ) Fiscal 2017 Quarter Ended, March 31, 2017 Unaudited June 30, 2017 Unaudited September 30, 2017 Unaudited December 31, 2017 Unaudited Revenue, net $ 5,475 $ 5,789 $ 4,177 $ 5,856 Gross profit $ 2,383 $ 2,302 $ 1,703 $ 2,759 Net loss $ (5,175 ) $ (5,007 ) $ (6,596 ) $ (1,064 ) Basic and diluted net loss per share $ (3.20 ) $ (3.09 ) $ (4.07 ) $ (0.04 )

Nature of Operations - Addition

Nature of Operations - Additional Information (Details) $ / shares in Units, $ in Thousands	Aug. 16, 2018USD ($)$ / sharesshares	Oct. 16, 2017USD ($)$ / sharesshares	Sep. 15, 2017	Dec. 31, 2018USD ($)$ / sharesshares	Dec. 31, 2017USD ($)$ / sharesshares
Nature of Operations [Line Items]
Aggregate net cash from initial public offering, after deducting underwriter discounts and commission | $					$ 22,114
Capital stock, authorized		310,000,000
Common stock, shares authorized		300,000,000		300,000,000	300,000,000
Preferred stock, shares authorized		10,000,000		10,000,000	10,000,000
Preferred stock, par value | $ / shares		$ 0.0001		$ 0.0001	$ 0.0001
Common stock, par value | $ / shares		$ 0.0001		$ 0.0001	$ 0.0001
Net cash from follow-on offering | $				$ 15,560
Reverse stock split of common stock, description			1-for-10 reverse stock split	1-for-15 reverse stock split
Reverse stock split of common stock, ratio			0.1
IPO
Nature of Operations [Line Items]
Number of common stock shares issued		3,897,910
Shares issued price per share | $ / shares		$ 7
Aggregate net cash from initial public offering, after deducting underwriter discounts and commission | $		$ 22,114
Offering costs | $		$ 5,171
Outstanding shares of convertible preferred stock converted into common stock		22,671,601
IPO | Subordinated Convertible Notes
Nature of Operations [Line Items]
Outstanding convertible notes converted into common stock		718,184
Over-Allotment Option
Nature of Operations [Line Items]
Number of common stock shares issued	1,500,000	322,910
Follow-on Public Offering
Nature of Operations [Line Items]
Number of common stock shares issued	10,000,000
Shares issued price per share | $ / shares	$ 1.50
Offering costs | $	$ 1,690
Net cash from follow-on offering | $	$ 15,560

Summary of Significant Accoun_4

Summary of Significant Accounting Policies - Additional Information (Details)	3 Months Ended	12 Months Ended
	Dec. 31, 2017USD ($)	Dec. 31, 2018USD ($)InstitutionCustomer	Dec. 31, 2017USD ($)Customer	Dec. 31, 2016USD ($)Customer
Summary Of Significant Accounting Policies [Line Items]
Accumulated deficit	$ (164,487,000)	$ (193,213,000)	$ (164,487,000)
Impairment of long-lived assets		$ 0	0	$ 0
Gain on sale of stock investment	1,851,000		1,851,000
Deferred revenue expected recognized period		1 year
Advertising costs		$ 297,000	99,000	130,000
Warrant period on ARTAS system accrues estimated future costs of repair		1 year
Effective tax benefit realized upon ultimate settlement		50.00%
Board of Directors
Summary Of Significant Accounting Policies [Line Items]
Defined contribution plan employer contribution amount		$ 0	$ 0	$ 0
Minimum | Property and Equipment
Summary Of Significant Accounting Policies [Line Items]
Depreciation and amortization, estimated useful lives of assets		3 years
Maximum | Property and Equipment
Summary Of Significant Accounting Policies [Line Items]
Depreciation and amortization, estimated useful lives of assets		5 years
Credit Concentration Risk
Summary Of Significant Accounting Policies [Line Items]
Number of financial institution | Institution		2
Credit Concentration Risk | Maximum
Summary Of Significant Accounting Policies [Line Items]
FDIC insured amount		$ 250,000
Customer Concentration Risk | Revenue
Summary Of Significant Accounting Policies [Line Items]
Number of major customers | Customer		0	0	0
Customer Concentration Risk | Accounts Receivable
Summary Of Significant Accounting Policies [Line Items]
Number of major customers | Customer		0	2
Concentration risk, percentage		10.00%
Allowance for doubtful accounts	229,000	$ 1,772,000	$ 229,000
Customer Concentration Risk | Customer One | Accounts Receivable
Summary Of Significant Accounting Policies [Line Items]
Concentration risk, percentage			10.00%
Customer Concentration Risk | Customer Two | Accounts Receivable
Summary Of Significant Accounting Policies [Line Items]
Concentration risk, percentage			11.00%
Collateral for Credit Cards | Other Assets
Summary Of Significant Accounting Policies [Line Items]
Restricted cash	$ 100,000	$ 83,000	$ 100,000

Summary of Significant Accoun_5

Summary of Significant Accounting Policies - Summary of Allowance for Doubtful Accounts (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Accounting Policies [Abstract]
Balance at Beginning of Year	$ 229
Charge to expense	1,772	$ 229
Write-offs, net of recoveries	(229)
Balance at End of Year	$ 1,772	$ 229

Net Loss Per Share - Outstandin

Net Loss Per Share - Outstanding Shares of Common Stock Equivalents Excluded from Calculation of Diluted Net Loss per Share Attributable to Common Stockholders (Details) - shares	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Total potential dilutive shares	4,261,643	2,237,208	23,359,178
Options to Purchase Common Stock
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Total potential dilutive shares	3,989,432	1,930,752	1,831,757
Warrants for Preferred Stock
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Total potential dilutive shares			385,126
Warrants for Common Stock
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Total potential dilutive shares	272,211	306,456
Convertible Preferred Stock
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Total potential dilutive shares			21,142,295

Fair Value Measurements - Sched

Fair Value Measurements - Schedule for Fair Value of Financial Assets and Liabilities by Level within Fair Value Hierarchy - (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Total assets	$ 14,051	$ 18,828
Quoted Prices in Active Markets using Identical Assets (Level 1)
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Total assets	14,051	18,828
Money Market Account
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Cash Equivalents	13,968	18,728
Restricted cash	83	100
Money Market Account | Quoted Prices in Active Markets using Identical Assets (Level 1)
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Cash Equivalents	13,968	18,728
Restricted cash	$ 83	$ 100

Fair Value Measurements - Sch_2

Fair Value Measurements - Schedule for Fair Value of Financial Assets and Liabilities by Level within Fair Value Hierarchy - (Parenthetical) (Details) $ in Thousands	Dec. 31, 2017USD ($)
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Cash equivalents	$ 18,728
Cash	4,817
Overstated
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Cash equivalents	$ 4,817

Balance Sheet Components - Sche

Balance Sheet Components - Schedule of Inventory (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Inventory Disclosure [Abstract]
Raw materials	$ 2,464
Work-in-process	323
Finished goods	2,735	$ 2,761
Total inventory	$ 5,522	$ 2,761

Balance Sheet Components - Sc_2

Balance Sheet Components - Schedule of Property and Equipment, Net (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Property Plant And Equipment [Abstract]
Computer hardware and software	$ 901	$ 721
Equipment	3,531	2,929
Leasehold improvements	874	869
Furniture and fixtures	457	270
Total property and equipment	5,763	4,789
Less: Accumulated depreciation and amortization	(4,464)	(3,651)
Total property and equipment, net	$ 1,299	$ 1,138

Balance Sheet Components - Addi

Balance Sheet Components - Additional Information (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Property Plant And Equipment [Abstract]
Depreciation and amortization	$ 813	$ 574	$ 654

Commitments and Contingencies -

Commitments and Contingencies - Additional Information (Details) $ in Thousands	1 Months Ended		3 Months Ended	12 Months Ended
	Feb. 29, 2012USD ($)	Jul. 31, 2006USD ($)shares	Dec. 31, 2018USD ($)ft²	Dec. 31, 2018USD ($)ft²AgreementComplaint	Dec. 31, 2017USD ($)	Dec. 31, 2016USD ($)
Commitment And Contingencies [Line Items]
Rent expense				$ 564	$ 413	$ 315
Charge related to excess purchase commitments			$ 188
Loss contingency accrual				$ 473
Number of complaints filed | Complaint				2
Evolve Manufacturing Technologies, Inc. | ARTAS Systems
Commitment And Contingencies [Line Items]
Number of master agreements | Agreement				2
Master agreement for purchase of robotic device, effective date				Apr. 1, 2016
Master agreement for purchase of kits used with robotic device, effective date				Mar. 1, 2016
Initial term of master agreements				2 years
Master agreements, renewal term				12 months
Master agreements, term description				Both agreements are effective for an initial term of two years and will continue to automatically renew for additional twelve-month periods, subject to either party’s right to terminate the agreement upon 180 days advance notice during the initial term, if our quarterly forecasted demand falls below 75% of our historical forecasted demand for the same period in the previous year or upon 120 days’ advance notice after the initial term.
Future purchase commitments			$ 330	$ 330
Rassman Licensing, LLC
Commitment And Contingencies [Line Items]
License agreement termination date		May 9, 2020
Rassman Licensing, LLC | License Agreement
Commitment And Contingencies [Line Items]
One time payment of royalty related to license	$ 400	$ 1,000
Royalty expense				$ 0	$ 0	$ 0
HSC Development, LLC
Commitment And Contingencies [Line Items]
License agreement termination date		Jul. 27, 2024
HSC Development, LLC | License Agreement
Commitment And Contingencies [Line Items]
One time payment of royalty related to license		$ 25
Number of common stock shares issued | shares		2,500
San Jose, California
Commitment And Contingencies [Line Items]
Operating lease office space area | ft²			23,000	23,000
Operating Lease manufacturing space area | ft²			2,500	2,500
Operating lease expiration date of office space area				2022-04
Operating lease expiration date of manufacturing space area				2019-04

Commitments and Contingencies_2

Commitments and Contingencies - Summary of Aggregate Future Minimum Lease Payments under Operating Leases (Details) $ in Thousands	Dec. 31, 2018USD ($)
Commitments And Contingencies Disclosure [Abstract]
2019	$ 518
2020	534
2021	550
2022	188
Total future minimum lease payments	$ 1,790

Long-Term Debt - Additional Inf

Long-Term Debt - Additional Information (Details) $ / shares in Units, $ in Thousands	Nov. 02, 2018USD ($)$ / sharesshares	May 31, 2018USD ($)	May 31, 2015USD ($)$ / sharesshares	Dec. 31, 2018USD ($)$ / sharesshares	Dec. 31, 2017USD ($)$ / shares	Oct. 16, 2017$ / shares	Jan. 31, 2015USD ($)
Debt Instrument [Line Items]
Net deferred debt costs				$ 1,363
Common stock, par value | $ / shares				$ 0.0001	$ 0.0001	$ 0.0001
Repayments of long-term debt				$ 13,300	$ 8,000
Loan and Security Agreement
Debt Instrument [Line Items]
Debt instrument, borrowed amount		$ 20,000
Debt instrument, term		4 years
Debt conversion, warrants issued | shares	161,725			161,725
Debt instrument, final payment amount upon maturity		$ 1,300
Debt instrument, outstanding balance				$ 20,000
Proceeds from loan used to repay debt		10,085
Debt instrument, outstanding balance repaid		8,667
Debt instrument accrued interest and prepayment fees		$ 118
Debt instrument, accrued interest				$ 178
Debt instrument, interest rate				10.30%
Debt instrument, interest only period				Dec. 1, 2019
Debt Instrument, full repayment date				May 1, 2022
Common stock, par value | $ / shares	$ 0.0001			$ 0.0001
Exercise price of warrants | $ / shares	$ 1.76			$ 3.71
Debt instrument, term	9 years 6 months			10 years
Fair value of warrants issued	$ 466			$ 404
Debt instrument transaction cost related amount				$ 505
Fee paid to lenders	$ 50
Cancellation of warrants | shares	161,725
Debt instrument, default interest percentage				4.00%
Percentage of prepayment premium				0.00%
Loan and Security Agreement | On Or Prior To May 1, 2019
Debt Instrument [Line Items]
Percentage of principal amount of borrowings being prepaid				3.00%
Loan and Security Agreement | After May 1, 2019 But On Or Prior To May 1, 2020
Debt Instrument [Line Items]
Percentage of principal amount of borrowings being prepaid				2.00%
Loan and Security Agreement | After May 1, 2020 But On Or Prior To May 1, 2021
Debt Instrument [Line Items]
Percentage of principal amount of borrowings being prepaid				1.00%
Loan and Security Agreement | Other Income (Expense), Net
Debt Instrument [Line Items]
Debt instrument, unamortized debt discount and fee amount				$ 404
Loan and Security Agreement | Measurement Input, Share Price
Debt Instrument [Line Items]
Warrants and Rights Outstanding, Measurement Input | $ / shares	1.96			3.71
Loan and Security Agreement | Measurement Input, Exercise Price
Debt Instrument [Line Items]
Warrants and Rights Outstanding, Measurement Input | $ / shares	1.76			3.71
Loan and Security Agreement | Measurement Input, Risk Free Interest Rate
Debt Instrument [Line Items]
Warrants and Rights Outstanding, Measurement Input	0.0322			0.0297
Loan and Security Agreement | Measurement Input, Price Volatility
Debt Instrument [Line Items]
Warrants and Rights Outstanding, Measurement Input	0.5970			0.5550
Loan and Security Agreement | Measurement Input, Expected Term
Debt Instrument [Line Items]
Debt instrument, term	10 years			10 years
Loan and Security Agreement | Measurement Input, Expected Dividend Rate
Debt Instrument [Line Items]
Warrants and Rights Outstanding, Measurement Input	0			0
Loan and Security Agreement | Maximum
Debt Instrument [Line Items]
Debt instrument, additional interest only period				3 months
Loan and Security Agreement | LIBOR
Debt Instrument [Line Items]
Debt instrument, basis spread on variable rate		7.95%
Loan and Security Agreement | Oxford Finance, LLC
Debt Instrument [Line Items]
Debt instrument, borrowed amount			$ 20,000
Credit facility fees							$ 246
Net deferred debt costs							$ 153
Debt Instrument, maturity month and year			2019-07
Debt instrument, final payment amount upon maturity			$ 1,300
Debt instrument, outstanding balance					13,300
Debt instrument, accrued interest					$ 85
Debt instrument, interest rate					13.00%
Loan and Security Agreement | Oxford Finance, LLC | Series C Convertible Preferred Stock
Debt Instrument [Line Items]
Debt conversion, warrants issued | shares			110,486
Shares issued price per share | $ / shares			$ 7.15
Loan and Security Agreement | Oxford Finance, LLC | Warrants for Preferred Stock
Debt Instrument [Line Items]
Debt instrument, term			10 years
Loan and Security Agreement | Oxford Finance, LLC | Prime Rate
Debt Instrument [Line Items]
Debt instrument, interest rate, stated percentage			8.50%

Long-Term Debt - Schedule Princ

Long-Term Debt - Schedule Principal Payments on Outstanding Borrowings (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Debt Disclosure [Abstract]
2019	$ 667
2020	8,000
2021	8,000
2022	4,163
Total	20,830
Less: debt discounts and issuance costs	(1,363)
Less: current portion	(49)	$ (7,730)
Non-current portion	$ 19,418	$ 5,271

Common Stock Reserved For Iss_3

Common Stock Reserved For Issuance - Schedule of Common Stock Reserved for Issuance (Details) - shares	Dec. 31, 2018	Dec. 31, 2017	Oct. 11, 2017	Dec. 31, 2016	Dec. 31, 2015
Class Of Stock [Line Items]
Outstanding and issued stock options	3,989,432	1,930,752		1,831,757	1,410,708
Shares reserved for future option grants	437,241	271,490
Total common stock reserved for issuance	4,698,884	2,508,698	2,220,587
Common Stock
Class Of Stock [Line Items]
Outstanding common stock warrants	272,211	306,456

Stock Option Plan - Additional

Stock Option Plan - Additional Information (Details) - USD ($)	Nov. 01, 2018	Oct. 11, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Shares reserved for issuance		2,220,587	4,698,884	2,508,698
Expected dividend			$ 0
Weighted-average grant date fair value of options granted			$ 1.06	$ 1.73	$ 0.86
Total intrinsic value of options exercised			$ 417,000	$ 1,180	$ 0
Unamortized stock-based compensation			$ 2,351,000
Unamortized stock-based compensation, weighted-average period			3 years 1 month 17 days
Restricted Stock Awards
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Unrecognized compensation expense, net of estimated forfeitures			$ 133,000
Expense recognition period			10 months
Aggregate intrinsic value of the RSUs outstanding			$ 157,000
Keith Sullivan | Maximum
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Term of office	1 year
Keith Sullivan | Restricted Stock Awards
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Number of stock awards granted	360,000
Vesting rights description	Under the terms of the arrangement, Mr. Sullivan was granted 360,000 restricted stock awards, which shall vest in quarterly installments equal to 25% of the shares starting with the first vest date on January 15, 2019 so long as Mr. Sullivan is providing services.
Vesting percentage	25.00%
First vest date	Jan. 15, 2019
2015 Plan
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Shares reserved for issuance		306,756
2017 Plan
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Shares reserved for issuance		1,913,831
Effective date of plan		Oct. 11, 2017
Annual increase in shares reserved for issuance beginning year		2018
Annual increase in shares reserved for issuance ending year		2027
Percentage threshold of increase in shares reserved for issuance		4.00%

Stock Option Plan - Summary of

Stock Option Plan - Summary of Recognized Stock-based Compensation Expense for Employees and Non-employees (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Stock-based compensation	$ 667	$ 465	$ 466
Employees and Non-employees
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Stock-based compensation	667	465	466
Cost of Revenue | Employees and Non-employees
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Stock-based compensation	19	10	12
Sales and Marketing | Employees and Non-employees
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Stock-based compensation	149	74	85
Research and Development | Employees and Non-employees
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Stock-based compensation	58	101	102
General and Administrative | Employees and Non-employees
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Stock-based compensation	$ 441	$ 280	$ 267

Stock Option Plan - Assumptions

Stock Option Plan - Assumptions used in Fair Value of Option Estimated at Date of Grant using Black-Scholes Option Pricing Formula (Details)	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Risk-free interest rate, minimum	2.40%	1.77%	1.30%
Risk-free interest rate, maximum	2.96%	2.13%	1.84%
Expected volatility, minimum	53.72%	51.62%	52.71%
Expected volatility, maximum	59.74%	55.38%	56.58%
Expected dividend rate	0.00%	0.00%	0.00%
Minimum
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Expected term (in years)	5 years 1 month 6 days	4 years 11 months 12 days	5 years 6 months 10 days
Maximum
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Expected term (in years)	6 years 1 month 6 days	7 years 6 months	6 years 1 month 9 days

Stock Option Plan - Summary o_2

Stock Option Plan - Summary of Stock Option Activity (Details) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Share Based Compensation Arrangement By Share Based Payment Award Options Outstanding Roll Forward
Number of Shares, Outstanding, Beginning Balance	1,930,752	1,831,757	1,410,708
Number of Shares, Options granted	2,551,707	192,420	1,179,644
Number of Shares, Options exercised	(236,730)	(21,843)	(20,218)
Number of Shares, Options cancelled	(256,297)	(71,582)	(737,377)
Number of Shares, Options expired			(1,000)
Number of Shares, Outstanding, Ending Balance	3,989,432	1,930,752	1,831,757
Number of Shares, Vested and expected to vest	3,531,802
Number of Shares, Exercisable	1,187,091
Weighted-Average Exercise Price Per Share, Outstanding, Beginning Balance	$ 1.90	$ 1.80	$ 1.90
Weighted-Average Exercise Price Per Share, Options granted	1.98	3.12	1.70
Weighted-Average Exercise Price Per Share, Options exercised	1.66	2.01	2
Weighted-Average Exercise Price Per Share, Options cancelled	2.03	1.81	2
Weighted-Average Exercise Price Per Share, Options expired			0.50
Weighted-Average Exercise Price Per Share, Outstanding, Ending Balance	1.95	$ 1.90	$ 1.80
Weighted-Average Exercise Price Per Share, Vested and expected to vest	1.96
Weighted-Average Exercise Price Per Share, Exercisable	$ 1.82
Weighted-Average Remaining Contractual Term, Outstanding	8 years 8 months 12 days	8 years 8 months 12 days	7 years 10 months 24 days
Weighted-Average Remaining Contractual Term, Vested and expected to vest	8 years 7 months 6 days
Weighted-Average Remaining Contractual Term, Exercisable	7 years 2 months 12 days
Aggregate Intrinsic Value, Outstanding		$ 5,322	$ 14

Income Taxes - Schedule of Geog

Income Taxes - Schedule of Geographical Breakdown of Loss Before Provision for Income Taxes (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Income Tax Disclosure [Abstract]
Domestic	$ (28,477)	$ (17,732)	$ (21,696)
Foreign	(202)	(54)	(150)
Net loss before provision for income taxes	$ (28,679)	$ (17,786)	$ (21,846)

Income Taxes - Schedule of Comp

Income Taxes - Schedule of Components of Provision for Income Taxes (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Current tax provision:
State	$ 9	$ 4	$ 4
Foreign	38	56	16
Total current tax provision	47	60	20
Deferred tax provision (benefit):
State		(4)	(4)
Foreign			(16)
Total deferred tax provision (benefit)		(4)	$ (20)
Total provision for income taxes	$ 47	$ 56

Income Taxes - Additional Infor

Income Taxes - Additional Information (Details) - USD ($)	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Income Taxes [Line Items]
Deferred tax assets, valuation allowance, change in amount	$ 6,156,000	$ (13,888,000)
Federal statutory rate	21.00%	34.00%	34.00%
Tax reforms impact on deferred balances	$ 21,000
Additional tax recognized	0
Deferred tax assets, federal operating loss carry forwards	178,393,000
Deferred tax assets, state operating loss carry forwards	$ 96,232,000
Operating loss carry forwards, expiry year start	2022
Operating loss carry forwards, expiry year end	2038
Federal research and development tax credit carryforwards	$ 1,602,000
State research and development tax credit carryforwards	$ 1,822,000
Federal research and development tax credit carryforwards, expiration starting year	2025
Cumulative amount undistributed earnings	$ 443,000
Earliest Tax Year
Income Taxes [Line Items]
Tax year	2002
Latest Tax Year
Income Taxes [Line Items]
Tax year	2018
South Korea
Income Taxes [Line Items]
Operating loss carry forwards, expiry year end	2025
Deferred tax assets, foreign operating loss carry forwards	$ 1,426,000
Maximum
Income Taxes [Line Items]
Federal statutory rate		35.00%

Income Taxes - Reconciliation b

Income Taxes - Reconciliation between Income Taxes Computed at Federal Statutory Income Tax Rate and Provision for Income Taxes (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Effective Income Tax Rate Continuing Operations Tax Rate Reconciliation [Abstract]
U.S. federal statutory income tax	$ (6,022)	$ (6,046)	$ (7,306)
Research tax credits	(112)	(75)	(99)
Stock-based compensation	66	85	102
Adjustment of deferred tax balances following changes in tax rates		20,748
Other	(41)	303	117
Change in valuation allowance	6,156	(14,955)	7,206
Total current tax provision	47	60	20
Total deferred tax benefit		(4)	$ (20)
Total provision for income taxes	$ 47	$ 56

Income Taxes - Reconciliation_2

Income Taxes - Reconciliation between Income Taxes Computed at Federal Statutory Income Tax Rate and Provision for Income Taxes (Parenthetical) (Details)	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Effective Income Tax Rate Continuing Operations Tax Rate Reconciliation [Abstract]
Federal statutory rate	21.00%	34.00%	34.00%

Income Taxes - Schedule of Co_2

Income Taxes - Schedule of Components of Deferred Tax Assets (Details) - USD ($)	Dec. 31, 2018	Dec. 31, 2017
Deferred tax assets:
Net operating loss carryforwards	$ 42,359,000	$ 37,173,000
Research and development credits	3,041,000	2,823,000
Accrual and reserves	2,003,000	1,251,000
Total deferred tax assets	47,403,000	41,247,000
Less: valuation allowance	(47,403,000)	$ (41,247,000)
Total net deferred tax assets	$ 0

Income Taxes - Schedule of Reco

Income Taxes - Schedule of Reconciliation of Uncertain Tax Position (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Income Tax Disclosure [Abstract]
Balance as of the beginning of the year	$ 1,362	$ 1,283
Increases related to tax positions in prior period	8	5
Increases related to tax positions taken during the current period	97	74
Balance at the end of the year	$ 1,467	$ 1,362

Segment and Geographic Inform_3

Segment and Geographic Information - Additional Information (Details)	12 Months Ended
	Dec. 31, 2018Segment
Segment Reporting [Abstract]
Number of operating segments	1
Number of reportable segments	1

Segment and Geographic Inform_4

Segment and Geographic Information - Schedule of Revenue by Geographic Area (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Revenues From External Customers And Long Lived Assets [Line Items]
Total revenue	$ 6,658	$ 4,818	$ 5,475	$ 5,005	$ 5,856	$ 4,177	$ 5,789	$ 5,475	$ 21,956	$ 21,297	$ 15,600
United States
Revenues From External Customers And Long Lived Assets [Line Items]
Total revenue									13,132	8,919	6,736
Europe and Middle East
Revenues From External Customers And Long Lived Assets [Line Items]
Total revenue									3,504	5,784	3,112
Asia Pacific
Revenues From External Customers And Long Lived Assets [Line Items]
Total revenue									4,007	4,353	3,552
Rest of World
Revenues From External Customers And Long Lived Assets [Line Items]
Total revenue									$ 1,313	$ 2,241	$ 2,200

Selected Quarterly Financial _3

Selected Quarterly Financial Data - Additional Information (Details)	Sep. 15, 2017	Dec. 31, 2018
Quarterly Financial Data [Abstract]
Reverse stock split	1-for-10 reverse stock split	1-for-15 reverse stock split
Reverse stock split, ratio	0.1

Selected Quarterly Financial _4

Selected Quarterly Financial Data (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Quarterly Financial Data [Abstract]
Revenue, net	$ 6,658	$ 4,818	$ 5,475	$ 5,005	$ 5,856	$ 4,177	$ 5,789	$ 5,475	$ 21,956	$ 21,297	$ 15,600
Gross profit	2,570	2,155	2,961	1,820	2,759	1,703	2,302	2,383	9,506	9,147	5,169
Net loss	$ (7,981)	$ (7,070)	$ (6,244)	$ (7,431)	$ (1,064)	$ (6,596)	$ (5,007)	$ (5,175)	$ (28,726)	$ (17,842)	$ (21,846)
Basic and diluted net loss per share	$ (0.20)	$ (0.20)	$ (0.21)	$ (0.26)	$ (0.04)	$ (4.07)	$ (3.09)	$ (3.20)	$ (0.86)	$ (2.42)	$ (13.54)

Related Party Transactions - Ad

Related Party Transactions - Additional Information (Details) - Member of Board of Directors - Commercial Transaction	12 Months Ended
	Dec. 31, 2017USD ($)
Related Party Transaction [Line Items]
Aggregate revenue	$ 83,000
Accounts receivable due from related party	$ 0

Subsequent Event (Unaudited) -

Subsequent Event (Unaudited) - Additional Information (Details)	Mar. 15, 2019USD ($)$ / sharesshares	Feb. 28, 2019USD ($)ConvertiblePromissoryNote	Sep. 15, 2017	Dec. 31, 2018shares	Dec. 31, 2017USD ($)shares	Feb. 13, 2019USD ($)	May 31, 2018USD ($)
Subsequent Event [Line Items]
Conversion of convertible notes to common stock, value					$ 5,027,000
Common stock, shares outstanding | shares				40,677,012	28,940,282
Reverse stock split			1-for-10 reverse stock split	1-for-15 reverse stock split
Reverse stock split of common stock, ratio			0.1
Loan and Security Agreement
Subsequent Event [Line Items]
Amount of convertible promissory notes authorized to issue							$ 20,000,000
Debt instrument, maturity date				May 1, 2022
Subsequent Event | Merger Agreement
Subsequent Event [Line Items]
Percentage of ownership acquired	15.00%
Common stock, shares outstanding | shares	283,200,000
Reverse stock split of common stock, ratio	0.0667
Subsequent Event | Merger Agreement | Reverse Stock Split
Subsequent Event [Line Items]
Common stock, shares outstanding | shares	18,900,000
Subsequent Event | Merger Agreement | Venus
Subsequent Event [Line Items]
Percentage of ownership acquired	85.00%
Subsequent Event | Merger Agreement | EW Healthcare Partners
Subsequent Event [Line Items]
Equity method investments amount	$ 21,000,000
Equity method investment price per share | $ / shares	$ 0.825
Subsequent Event | Loan and Security Agreement | Third Amendment
Subsequent Event [Line Items]
Debt instrument final fee payable increased amount						$ 960,000
Subsequent Event | 8% Unsecured Convertible Promissory Notes | Note Purchase Agreement
Subsequent Event [Line Items]
Amount of convertible promissory notes authorized to issue		$ 5,000,000
Number of convertible promissory notes issued | ConvertiblePromissoryNote		2
Debt instrument, maturity date		Aug. 28, 2020
Debt instrument, interest rate, stated percentage		8.00%
Subsequent Event | 8% Unsecured Convertible Promissory Notes | Note Purchase Agreement | Minimum
Subsequent Event [Line Items]
Conversion of convertible notes to common stock, value		$ 20,000,000
Subsequent Event | Unsecured Convertible Promissory Notes | Merger Agreement | Fred Moll and Inter West Partners
Subsequent Event [Line Items]
Amount of convertible promissory notes authorized to issue	$ 5,000,000
Conversion price of convertible promissory notes | $ / shares	$ 0.825
Subsequent Event | Unsecured Convertible Promissory Notes | Note Purchase Agreement
Subsequent Event [Line Items]
Amount of convertible promissory notes authorized to issue		$ 5,000,000