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Document and Entity Information - shares	3 Months Ended
Document and Entity Information - shares	Mar. 31, 2019	May 03, 2019
Document And Entity Information [Abstract]
Document Type	10-Q
Amendment Flag	false
Document Period End Date	Mar. 31, 2019
Document Fiscal Year Focus	2019
Document Fiscal Period Focus	Q1
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 Small Business	true
Entity Emerging Growth Company	true
Entity Ex Transition Period	false
Entity Common Stock, Shares Outstanding		40,857,012

Condensed Consolidated Balance Sheets (Unaudited) - USD ($) $ in Thousands	Mar. 31, 2019	Dec. 31, 2018
CURRENT ASSETS:
Cash and cash equivalents	$ 14,957	$ 16,122
Accounts receivable, net of allowance of $1,963 and $1,772 as of March 31, 2019 and December 31, 2018, respectively	6,699	6,569
Inventory	5,207	5,522
Prepaid expenses and other current assets	1,239	1,278
Total current assets	28,102	29,491
Property and equipment, net	1,471	1,299
Restricted cash	83	83
Other assets	166	100
TOTAL ASSETS	29,822	30,973
CURRENT LIABILITIES:
Accounts payable	4,193	3,815
Accrued compensation	1,515	1,771
Other accrued liabilities	2,920	2,337
Deferred revenue	1,384	1,407
Current portion of long-term debt, net of discount of $693 and $617 as of March 31, 2019 and December 31, 2018, respectively	1,974	49
Total current liabilities	11,986	9,379
Other long-term liabilities	655	594
Related party convertible promissory notes (Note 8)	5,000
Long-term debt, net of discount of $638 and $746 as of March 31, 2019 and December 31, 2018	17,655	19,418
TOTAL LIABILITIES	35,296	29,391
Commitments and Contingencies (Note 6)
STOCKHOLDERS’ EQUITY (DEFICIT)
Common stock, $0.0001 par value; 300,000,000 shares authorized as of March 31, 2019 and December 31, 2018; 40,767,012 and 40,677,012 shares issued and outstanding as of March 31, 2019 and December 31, 2018, respectively	4	4
Additional paid-in capital	195,189	194,841
Accumulated other comprehensive loss	(14)	(50)
Accumulated deficit	(200,653)	(193,213)
TOTAL STOCKHOLDERS’ EQUITY (DEFICIT)	(5,474)	1,582
TOTAL LIABILITIES AND STOCKHOLDERS’ EQUITY (DEFICIT)	$ 29,822	$ 30,973

Condensed Consolidated Balance Sheets (Unaudited) (Parenthetical) - USD ($) $ in Thousands	Mar. 31, 2019	Dec. 31, 2018
Statement Of Financial Position [Abstract]
Accounts receivable, allowance	$ 1,963	$ 1,772
Current portion of long-term debt, discount	693	617
Long-term debt, discount	$ 638	$ 746
Convertible preferred stock at liquidation preference par value	$ 0.0001	$ 0.0001
Convertible preferred stock, shares authorized	10,000,000	10,000,000
Convertible preferred stock, shares issued	0	0
Convertible 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	40,767,012	40,767,012
Common stock, shares outstanding	40,677,012	40,677,012

Condensed Consolidated Statements of Operations (Unaudited) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Income Statement [Abstract]
Revenue	$ 5,394	$ 5,005
Cost of revenue	2,457	3,185
Gross profit	2,937	1,820
Operating expenses:
Sales and marketing	4,570	4,384
Research and development	1,488	2,125
General and administrative	1,992	2,351
Merger related expenses	1,501
Total operating expenses	9,551	8,860
Loss from operations	(6,614)	(7,040)
Other expense, net:
Interest expense	(766)	(358)
Other expense, net	(46)	(20)
Total other expense, net	(812)	(378)
Net loss before provision for income taxes	(7,426)	(7,418)
Provision for income taxes	14	13
Net loss attributable to common stockholders	$ (7,440)	$ (7,431)
Net loss per share attributable to common stockholders, basic and diluted	$ (0.18)	$ (0.26)
Weighted-average shares used in computing net loss per share attributable to common stockholders, basic and diluted	40,753,012	28,962,269

Condensed Consolidated Statement of Stockholders' Equity (Deficit) (Unaudited) - 3 months ended Mar. 31, 2019 - USD ($) $ in Thousands	Total	Common Stock	Additional Paid-in Capital	Accumulated Other Comprehensive Income (Loss)	Accumulated Deficit
Beginning balance, value at Dec. 31, 2018	$ 1,582	$ 4	$ 194,841	$ (50)	$ (193,213)
Beginning balance, shares at Dec. 31, 2018		40,677,012
Release of restricted stock awards, shares		90,000
Stock-based compensation	348		348
Other comprehensive gain	36			36
Net loss	(7,440)				(7,440)
Ending balance, value at Mar. 31, 2019	$ (5,474)	$ 4	$ 195,189	$ (14)	$ (200,653)
Ending balance, shares at Mar. 31, 2019		40,767,012

- Definition

The portion of profit or loss for the period, net of income taxes, which is attributable to the parent.

+ References + Details

Condensed Consolidated Statements of Cash Flows (Unaudited) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
CASH FLOWS FROM OPERATING ACTIVITIES:
Net loss	$ (7,440)	$ (7,431)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation and amortization	149	132
Amortization of debt discounts and issuance costs	179	94
Stock-based compensation	348	125
Provision for bad debt	191	263
Changes in operating assets and liabilities:
Accounts receivable	(321)	(876)
Inventory	315	539
Prepaid expenses and other assets	(28)	230
Accounts payable	403	300
Accrued and other liabilities	329	1,062
Deferred revenue	36	607
Net cash used in operating activities	(5,839)	(4,955)
CASH FLOWS FROM INVESTING ACTIVITIES:
Purchases of property and equipment	(346)	(260)
Net cash used in investing activities	(346)	(260)
CASH FLOWS FROM FINANCING ACTIVITIES:
Proceeds from related party convertible promissory notes, net	4,984
Proceeds from exercised stock options		196
Principal payments on long-term debt		(2,000)
Net cash provided by (used in) financing activities	4,984	(1,804)
Effect of exchange rate changes on cash, cash equivalents and restricted cash	36	4
NET DECREASE IN CASH, CASH EQUIVALENTS AND RESTRICTED CASH	(1,165)	(7,015)
CASH, CASH EQUIVALENTS AND RESTRICTED CASH — Beginning of period	16,205	23,645
CASH, CASH EQUIVALENTS AND RESTRICTED CASH — End of period	15,040	16,630
SUPPLEMENTAL DISCLOSURES OF CASH FLOW INFORMATION:
Interest paid during the period	549	275
SUPPLEMENTAL DISCLOSURES OF NON-CASH INVESTING AND FINANCING INFORMATION:
Purchase of property and equipment included in accounts payable	25	$ 10
Discounts in connection with amendment of long-term debt	$ 130

Summary of Significant Accounting Policies

3 Months Ended

Mar. 31, 2019

Accounting Policies [Abstract]

Summary of Significant Accounting Policies

2. SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES

Liquidity

These condensed 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 March 31, 2019, and December 31, 2018, the Company has an accumulated deficit of $200,653 and $193,213 and, as of such dates, and through the date of this filing, does not have sufficient capital to fund its planned operations. Because 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 report on the Company’s consolidated financial statements as of, and for the year ended, December 31, 2018 that such factors raise substantial doubt about the Company’s ability to continue as a going concern. To continue its operations, the Company must achieve profitable operations and/or obtain additional financing. Until the Company generates revenue at a level to support its cost structure, the Company expects to continue to incur substantial operating losses and net cash outflows. The Company may never become profitable and even if it does attain profitable operations, it may not be able to sustain profitability or positive cash flows on a recurring basis.

The Company will need to raise further capital in the future to service its debt or 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 condensed 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 condensed 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 condensed consolidated balance sheet as of March 31, 2019, the condensed consolidated statements of operations and condensed consolidated statements of comprehensive loss for the three months ended March 31, 2019 and 2018, the condensed consolidated statements of cash flows for the three months ended March 31, 2019 and 2018 and the condensed consolidated statement of stockholders’ equity (deficit) for the three months ended March 31, 2019 are unaudited. The accompanying unaudited condensed consolidated financial statements have been prepared in accordance with generally accepted accounting principles in the United States (U.S. GAAP) and in the opinion of management, reflect all adjustments of a normal and recurring nature that are necessary for the fair presentation of the Company’s condensed consolidated financial statements included in this report. The condensed consolidated financial data disclosed in these notes to the condensed consolidated financial statements related to the three-month periods are also unaudited. The condensed consolidated results of operations for the three months ended March 31, 2019 are not necessarily indicative of the results to be expected for the year ending December 31, 2019, or for any other future annual or interim period. The consolidated balance sheet as of December 31, 2018 included herein was derived from the audited consolidated financial statements as of that date. These condensed consolidated financial statements should be read in conjunction with the Company’s audited consolidated financial statements included in its Annual Report filed on Form 10-K for the year ended December 31, 2018, with the SEC on March 20, 2019.

Principles of Consolidation

The accompanying condensed consolidated financial statements include the accounts of Restoration Robotics, Inc. and its wholly owned subsidiaries, which are organized in the United States, United Kingdom, Spain, Hong Kong and South Korea. All significant intercompany accounts and transactions have been eliminated in consolidation.

Use of Estimates

The preparation of the condensed 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 condensed consolidated financial statements and the reported amounts of revenue and expenses during the reporting period. Significant estimates and assumptions made in the accompanying condensed 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 and related valuation allowance. 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.

Cash, Cash Equivalents, and Restricted Cash

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. The Company’s restricted cash is held in a separate money market account as collateral for credit cards.

The following table provides a reconciliation of cash, cash equivalents, and restricted cash reported within the balance sheets that sum to the total of the same amounts shown in the condensed consolidated statements of cash flows.

	March 31, 2019		December 31, 2018
Cash and cash equivalents	$	14,957	$	16,122
Restricted cash		83		83
Total cash, cash equivalents and restricted cash in the condensed consolidated statements of cash flows	$	15,040	$	16,205

Segments

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.

Concentration of Customers

For the three months ended March 31, 2019, one customer accounted for more than 10% of the Company’s revenue. For the three months ended March 31, 2018, no customer accounted for more than 10% of the Company’s revenue. As of March 31, 2019, and December 31, 2018, no customers accounted for more than 10% of the Company’s accounts receivable.

JOBS Act Accounting Election

The Company is an emerging growth company, as defined in the Jumpstart Our Business Startups Act of 2012 (the JOBS Act). Under the JOBS Act, emerging growth companies can delay adopting new or revised accounting standards issued after the enactment of the JOBS Act until 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 condensed 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 Adopted Accounting Standards

In May 2014, the Financial Accounting Standards Board (FASB) issued Accounting Standards Update (ASU) No. 2014‑09, Revenue from Contracts with Customers (Topic 606), as amended by ASU No. 2015-14, ASU No. 2016-08, ASU No. 2016-10, ASU No. 2016-12, and ASU No. 2016-20, (collectively, ASU 2014-09). ASU 2014-09 establishes a principle for recognizing revenue upon the transfer of promised goods or services to customers in an amount that reflects the expected consideration received in exchange for those goods or services and provides guidance on the recognition of costs related to obtaining and fulfilling customer contracts. ASU 2014-09 is required to be adopted, using either of two methods: (i) retrospective to each prior reporting period presented with the option to elect certain practical expedients as defined within ASU 2014-09; or (ii) retrospective with the cumulative effect of initially applying ASU 2014-09 recognized at the date of initial application and providing certain additional disclosures. The Company adopted the new revenue standard on January 1, 2019, using the modified retrospective transition method applied to those contracts which were not completed as of that date. See Note 3. Revenue, to our unaudited condensed consolidated financial statements included in this Quarterly Report on Form 10-Q for additional details.

In June 2018, the FASB issued ASU No. 2018-7, Compensation – Stock Compensation (Topic 718)— Improvements to Nonemployee Share-Based Payment Accounting. This guidance supersedes ASC 505-50 and expands the scope of ASC 718 to include all share-based payment arrangements related to the acquisition of goods and services from both nonemployees and employees. The amendments should be applied on a modified retrospective basis through a cumulative-effect adjustment to retained earnings as of the beginning of the fiscal year of adoption. The Company adopted this standard on January 1, 2019 using the modified retrospective adoption method. The adoption of this standard did not have a material impact on the Company’s condensed consolidated financial statements and related disclosures and no cumulative-effect adjustment was recorded to accumulated deficit at January 1, 2019.

Recently Issued Accounting Standards Not Yet Adopted

In February 2016, the FASB issued ASU No. 2016‑02, Leases (Topic 842), or ASU 2016‑02, as amended by ASU 2019-01 issued in March 2019, (collectively, ASU 2016-02), which requires lessees to record most leases on their balance sheets but recognize the expenses on their income statements in a manner similar to current practice. Under ASU 2016‑02, a lessee would recognize a lease liability for the obligation to make lease payments and a right‑to‑use asset for the right to use the underlying asset for the lease term. For public entities, this standard is effective for annual reporting periods beginning after December 15, 2018, including interim periods within that reporting period. As an Emerging Growth Company, this standard is effective for the Company in annual reporting periods beginning after December 15, 2019, and interim periods within annual periods beginning after December 15, 2020. Early adoption is permitted. The Company is currently evaluating the standard and its impact on the condensed consolidated financial statements. However, the Company does expect a material change in its consolidated assets and liabilities upon adoption of this standard.

Revenue

3 Months Ended

Mar. 31, 2019

Revenues [Abstract]

Revenue

3. REVENUE

Change in Accounting Principle

In May 2014, the FASB issued ASU 2014-09, Revenue from Contracts with Customers (Topic 606). Topic 606 supersedes the revenue recognition requirements in Topic 605 Revenue Recognition (Topic 605) and requires entities to recognize revenue when control of the promised goods or services is transferred to customers at an amount that reflects the consideration to which the entity expects to be entitled in exchange for those goods or services. The FASB has issued several amendments to the standard, including clarifications on disclosure of prior-period performance obligations and remaining performance obligations.

The guidance permits two methods of adoption: retrospectively to each prior reporting period presented (full retrospective method), or retrospectively with the cumulative effect of initially applying the guidance recognized at the date of initial application (the modified retrospective method). The Company adopted the standard effective January 1, 2019 using the modified retrospective method. This approach was applied to all contracts that were not completed as of January 1, 2019. The adoption of Topic 606 did not have a material impact on the Company’s historical net losses and, therefore, no adjustment was made to the opening balance of accumulated deficit at January 1, 2019. Therefore, the comparative 2018 period has not been adjusted and continues to be reported under Topic 605.

Topic 606’s core principle is that a reporting entity will recognize revenue when it transfers promised goods or services to customers in an amount that reflects the consideration to which the entity expects to be entitled in exchange for those goods or services. In applying this new guidance to contracts within its scope, an entity will:

•

Identify the contract(s) with a customer;

•

Identify the performance obligations in the contract;

•

Determine the transaction price;

•

Allocate the transaction price to the performance obligations in the contract; and

•

Recognize revenue when (or as) the entity satisfies a performance obligation.

Impact on Financial Statements

In accordance with Topic 606, the disclosure of the impact of the change in accounting principle to the unaudited condensed consolidated statements of operations and balance sheets was as follows:

	Three months ended March 31, 2019
Condensed Consolidated Statements of Operations Data	As Reported			Adjustments			Balance Without ASC 606 Adoption
Revenue	$	5,394		$	(169	)	$	5,225
Gross profit		2,937			(169	)		2,768
Total operating expenses		9,551			11			9,562
Loss from operations		(6,614	)		(180	)		(6,794	)
Net loss before provision for income taxes		(7,426	)		(180	)		(7,606	)
Net loss attributable to common stockholders	$	(7,440	)	$	(180	)	$	(7,620	)
Net loss per share attributable to common stockholders, basic and diluted	$	(0.18	)	$	(0.01	)	$	(0.19	)
Weighted-average shares used in computing net loss per share attributable to common stockholders, basic and diluted		40,753,012						40,753,012

	March 31, 2019
Condensed Consolidated Balance Sheets Data	As Reported			Adjustments			Balance Without ASC 606 Adoption
Assets
Prepaid expenses and other current assets	$	1,239		$	(132	)	$	1,107
Other assets		166			(48	)		118
Stockholders' deficit
Accumulated deficit		(200,653	)		(180	)		(200,833	)

Revenue Recognition

The Company generates revenue primarily through the sale and delivery of promised goods and services, which consists of the sale of ARTAS^® and ARTAS^® iX Systems, training on the systems, extended service contracts, consumables and marketing services. Revenue is recognized when control is transferred to customers, in an amount that reflects the consideration the Company expects to be entitled to in exchange for the goods or services. Sales prices are documented in the executed sales contract or purchase order prior to the transfer of control to the customer. Customers may enter into a separate extended service agreement (referred to as ARTAS Care) to purchase an extended warranty for products from the Company whereby the payment is due at the inception of the agreement or in monthly installment payments. Revenue for ARTAS Care is recognized ratably over the term of the agreement.

The Company also utilizes distributors to sell ARTAS^® and ARTAS^® iX Systems and related consumables in certain markets outside of the United States. The Company recognizes revenue when control of the goods or services is transferred to the distributors. Standard terms for all agreements with either end customers or distributors do not allow for right of return, refunds, payment contingent on obtaining financing or other terms that could impact the customer’s payment obligation. Payment terms for U.S. customers are generally at shipment, delivery, or within 30 day of shipment, while payment terms for customers outside of the U.S. vary between 30 and 180 days after shipment.

Performance Obligations, Determination and Allocation of Transaction Price and Method of Recognition

The Company's system sale arrangements generally contain multiple products and services. For these bundled sale arrangements, the Company accounts for individual products and services as separate performance obligations. These performance obligations include: ARTAS^® or ARTAS^® iX System, including related accessories and software license (considered as one performance obligation), product training, consumables (consisting of harvest or site making/implantation kits), extended service contracts and marketing services. All ARTAS^® and ARTAS^® iX Systems include an assurance-type standard warranty, generally for a 12-month period. ARTAS Care (extended warranty service contract) will commence at the expiration of the standard warranty period. For multiple performance obligations arrangements, the Company allocates revenue to each performance obligation based on its relative standalone selling price (SSP), which is based on a combination of observable prices or management’s best estimate of standalone selling price when an observable price is not available.

ARTAS^® and ARTAS^® iX Systems and consumables are performance obligations that are satisfied at a point in time (upon shipment), whereas ARTAS Care, product training, and marketing services are performance obligations that are satisfied over time (e.g. straight line over the performance period or as training and marketing services are performed).

The following table includes estimated revenue expected to be recognized in the future related to performance obligations that are unsatisfied or partially unsatisfied at the end of the reporting period as follows (in thousands):

Revenue	2019		2020		2021		2022 and Thereafter		Total
System related	$	339	$	—	$	—	$	—	$	339
Procedure-based		238		—		—		—		238
Service-related fees		807		176		25		112		1,120
Total	$	1,384	$	176	$	25	$	112	$	1,697

Shipping and Freight Costs

Shipping and freight costs are treated as fulfillment costs. For shipments to end-customers, the customer bears the shipping and freight costs and has control of the product upon shipment. For shipments to distributors, the distributor bears the shipping and freight costs, including insurance, tariffs and other import/export costs. Additionally, sale taxes are excluded from revenue.

Practical Expedients

In connection with the Company’s adoption of Topic 606, the Company elected to use the following practical expedients (i) not to adjust the promised amount of consideration for the effects of a significant financing component when the Company expects, at contract inception, that the period between the Company's transfer of a promised product or service to a customer and when the customer pays for that product or service will be one year or less; (ii) to expense costs as incurred for costs to obtain a contract when the amortization period would have been one year or less; and (iii) not to recast revenue for contracts that begin and end in the same fiscal year.

Costs to Obtain Customer Contracts

Sales commissions and related expenses are considered incremental and recoverable costs of acquiring customer contracts. Except for sales commissions that would have been amortized in one year or less, which we have elected the practical expedient discussed above, certain sales commissions related to ARTAS Care and consumables that are sold bundled with the ARTAS^® and ARTAS^® iX Systems, are capitalized and amortized on a straight-line basis over the anticipated period of benefit, which we have estimated to be three years for ARTAS Care extended warranty service contracts and five years for consumables. We determined the period of benefit by taking into consideration the length of the customer contracts, the Company’s technology lifecycle, and other factors. Amortization expense is recorded in sales and marketing expense within the condensed consolidated statement of operations. As of March 31, 2019, short-term and long-term unamortized deferred compensation were $3 and $8, which are included in “Prepaid and other current assets” and “Other Assets,” respectively, on the condensed consolidated balance sheets.

Deferred Revenue (Remaining Performance Obligations)

The aggregate balance of remaining performance obligations represents contracted revenue that has not yet been recognized primarily from ARTAS Care extended warranty service contracts, product training and marketing services not yet rendered to customers.

	Three months ended March 31, 2019
Balance at the beginning of the period	$	1,661
Additions		615
Recognition of deferred revenue		(579	)
Balance at the end of the period	$	1,697
Less: Deferred revenue - current	$	1,384
Deferred revenue - non-current (A)	$	313

(A)

Included in “Other long-term liabilities” on the condensed consolidated balance sheets as of March 31, 2019.

Disaggregation of Revenue

The Company disaggregates revenue from contracts with customers into geographical regions and by the timing of when goods and services are transferred. The Company determined that disaggregating revenue into these categories depicts how the nature, amount, timing and uncertainty of revenue and cash flows are affected by regional economic factors.

The following tables provide information about disaggregated revenue from contracts with customers into geographic regions, and the nature of the products and services:

	Three Months Ended
	March 31,
	2019		2018
United States	$	3,183	$	2,255
Europe and Middle East		1,115		973
Asia Pacific		688		1,104
Rest of World		408		673
Total revenue	$	5,394	$	5,005

	Three Months Ended
	March 31,
	2019		2018
Systems	$	3,553	$	2,005
Procedure-based		1,362		2,473
Service-related fees		479		527
Total revenue	$	5,394	$	5,005

Fair Value Measurements

3 Months Ended

Mar. 31, 2019

Fair Value Disclosures [Abstract]

Fair Value Measurements

5. FAIR VALUE MEASUREMENTS

Cash and cash equivalents, restricted cash, accounts receivable, accounts payable, and accrued liabilities approximate fair market value because of the short-term nature of those instruments. The Company’s Term Loan with Solar and Convertible Promissory Notes (both discussed further in Note 8) have fair values that approximate their carrying value.

U.S. GAAP establishes a framework for measuring fair value and a fair value hierarchy based on the inputs used to measure fair value. This framework maximizes the use of observable inputs and minimizes the use of unobservable inputs by requiring that the observable inputs be used when available. Fair value is defined as the price that would be received to sell an asset or paid to transfer a liability in an orderly transaction between market participants at the measurement date. It applies to both items recognized and reported at fair value in the condensed consolidated financial statements and items disclosed at fair value in the notes to the condensed consolidated financial statements.

Observable inputs are inputs that market participants would use in pricing the asset or liability based on market data obtained from independent sources. Unobservable inputs reflect assumptions that market participants would use in pricing the asset or liability based on the best information available in the circumstances. The hierarchy is broken down into three levels based on the transparency of inputs as follows:

Level 1 - Quoted prices are available in active markets for identical assets or liabilities as of the report date. A quoted price for an identical asset or liability in an active market provides the most reliable fair value measurement because it is directly observable to the market.

Level 2 - Pricing inputs are other than quoted prices in active markets, which are either directly or indirectly observable as of the report date. The nature of these securities includes investments for which quoted prices are available but traded less frequently and investments that are fair valued using other securities, the parameters of which can be directly observed.

Level 3 - Securities that have little to no pricing observability as of the report date. These securities are measured using management’s best estimate of fair value, where the inputs into the determination of fair value are not observable and require significant management judgment or estimation.

A financial instrument’s level within the fair value hierarchy is based on the lowest level of any input that is significant to the fair value measurement. However, the determination of what constitutes “observable” requires significant judgment by the Company. The categorization of a financial instrument within the hierarchy is based upon the pricing transparency of the instrument and does not necessarily correspond to the Company’s perceived risk of that instrument.

The following tables summarize the levels of fair value measurements of the Company’s cash equivalents:

	Fair Value Measurements as of March 31, 2019
	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	$	13,715	$	—	$	—	$	13,715
Restricted cash:
Money market account		83		—		—		83
Total assets	$	13,798	$	—	$	—	$	13,798

	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

- Definition

The entire disclosure for the fair value of financial instruments (as defined), including financial assets and financial liabilities (collectively, as defined), and the measurements of those instruments as well as disclosures related to the fair value of non-financial assets and liabilities. Such disclosures about the financial instruments, assets, and liabilities would include: (1) the fair value of the required items together with their carrying amounts (as appropriate); (2) for items for which it is not practicable to estimate fair value, disclosure would include: (a) information pertinent to estimating fair value (including, carrying amount, effective interest rate, and maturity, and (b) the reasons why it is not practicable to estimate fair value; (3) significant concentrations of credit risk including: (a) information about the activity, region, or economic characteristics identifying a concentration, (b) the maximum amount of loss the entity is exposed to based on the gross fair value of the related item, (c) policy for requiring collateral or other security and information as to accessing such collateral or security, and (d) the nature and brief description of such collateral or security; (4) quantitative information about market risks and how such risks are managed; (5) for items measured on both a recurring and nonrecurring basis information regarding the inputs used to develop the fair value measurement; and (6) for items presented in the financial statement for which fair value measurement is elected: (a) information necessary to understand the reasons for the election, (b) discussion of the effect of fair value changes on earnings, (c) a description of [similar groups] items for which the election is made and the relation thereof to the balance sheet, the aggregate carrying value of items included in the balance sheet that are not eligible for the election; (7) all other required (as defined) and desired information.

+ References + Details

Balance Sheet Components

3 Months Ended

Mar. 31, 2019

Balance Sheet Components [Abstract]

Balance Sheet Components

6. BALANCE SHEET COMPONENTS

Inventory

Inventory consists of the following:

	March 31,		December 31,
	2019		2018
Raw materials	$	2,114	$	2,464
Work-in-process		92		323
Finished goods		3,001		2,735
Total inventory	$	5,207	$	5,522

Property and Equipment, Net

Property and equipment, net consist of the following:

	March 31,			December 31,
	2019			2018
Equipment	$	3,844		$	3,531
Computer hardware and software		910			901
Leasehold improvements		874			874
Furniture and fixtures		457			457
Total property and equipment		6,085			5,763
Less: Accumulated depreciation and amortization		(4,614	)		(4,464	)
Total property and equipment, net	$	1,471		$	1,299

Depreciation and amortization expense was $149 and $132 for three months ended March 31, 2019 and 2018, respectively.

Commitments and Contingencies

3 Months Ended

Mar. 31, 2019

Commitments And Contingencies Disclosure [Abstract]

Commitments and Contingencies

7. 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 expire in April 2022 and April 2019, respectively. After April 2019, our manufacturing space is on a month-to-month lease arrangement.

Aggregate future minimum lease payments required under the Company’s operating leases as of March 31, 2019 are as follows:

Years Ending December 31,
2019 (remaining 9 months)	$	389
2020		534
2021		550
2022		188
Total future minimum lease payments	$	1,661

Total rent expense was $163 and $103 for three months ended March 31, 2019 and 2018, respectively.

Commitments

The Company has two master agreements and a component pricing agreement with Evolve Manufacturing Technologies, Inc. (Evolve) for the supply of the ARTAS^® System and consumable products. The terms of these master agreements are substantially similar. The master agreement for the sale of ARTAS^® Systems was effective beginning on April 1, 2016 and the master agreement for the sale of kits used with the ARTAS System was effective beginning on March 1, 2016. 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. Under the agreements, the Company has future purchase commitments up to $285 as of March 31, 2019.

In March 2018, the Company received U.S. FDA 510(k) clearance to expand the ARTAS^® System technology to include an implantation functionality, referred to as ARTAS^® iX. Based on manufacturing changes associated with the ARTAS^® iX System, the Company determined that certain components procured or expected to be procured by Evolve, will be in excess of expected demand or usage based on the advance notice the Company provided to Evolve under the term of the agreement mentioned above. Additionally, in the fourth quarter of 2018, the Company recorded a $188 charge related to other excess purchase commitments from another vendor based on cost reduction changes in 2019. Although the Company will be taking steps to minimize the adverse impact on the Company’s business, based on information available as of March 31, 2019, the Company’s management recorded a loss contingency accrual of $473 which is included in “Other accrued liabilities” on the condensed consolidated balance sheets as of March 31, 2019.

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 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 perpetual license to a patent subject to this license agreement.

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.

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 the Company, 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. On October 25, 2018, the Court ordered the defendants’ demurrers to the complaint sustained with leave to amend and granted an extension of time for plaintiff to serve a First Amended Complaint until further order of the Court. On January 31, 2019, the Court stayed the case and stayed any decision on the Company’s motion to dismiss on forum selection grounds pending resolution of an appeal of Sciabacucchi v. Salzberg, a case addressing similar issues in Delaware.

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. On November 30, 2018, Lead Plaintiff Edgardo Guerrini filed a Consolidated Amended Complaint for violations of federal securities laws asserting the same claims, against the same defendants, as his original complaint but adding certain allegations in support of those claims. On January 29, 2019, the Company, along with certain of its current and former executive officers and directors, filed a motion to dismiss the Consolidated Amended Complaint for failure to state a claim under Federal Rule of Civil Procedure 12(b)(6). The venture capital defendants and underwriter defendants filed joinders to the Company’s motion to dismiss on the same day. A hearing on the Company’s motion to dismiss is scheduled for July 11, 2019. The Company is unable to predict the date on which the District Court will issue any decision on the motion to dismiss at this time.

The Company believes that these lawsuits are without merit and management intends to vigorously defend against these claims.

Long-Term Debt

3 Months Ended

Mar. 31, 2019

Debt Disclosure [Abstract]

Long-Term Debt

8. LONG-TERM DEBT

Issuance of Related Party Convertible Promissory Notes

On February 28, 2019, the Company entered into a Note Purchase Agreement pursuant to which the Company raised $5,000 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.

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 $20,000. The Company anticipates that the potential Equity Financing discussed above will constitute a Qualified Financing. 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. Issuance costs associated with the Notes were not significant and accrued interest of $35 through March 31, 2019 is reported in “Other Long-Term Liabilities” on the condensed consolidated balance sheets.

Loan and Security Agreement

In May 2018, the Company entered into a Loan and Security Agreement and as subsequently amended (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 to Oxford Finance LLC (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 $180 as of March 31, 2019. The Interest Rate was 10.1% at March 31, 2019.

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 condensed consolidated 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 $404 are accounted for as a debt discount and classified within notes payable on the Company’s condensed consolidated 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 condensed 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 thresholds. 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. All other terms of the Warrants were unchanged.

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. As of March 31, 2019, 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 March 31, 2019 are as follows:

	As of
	March 31, 2019
2019 (remaining 9 months)	$	667
2020		13,000
2021		8,000
2022		4,293
2023		—
Total		25,960
Less debt discount		(1,331	)
Less current portion		(1,974	)
Non-current portion	$	22,655
Reported as:
Convertible promissory notes	$	5,000
Long-term debt		17,655
Total non-current portion	$	22,655

Stock Option Plan

3 Months Ended

Mar. 31, 2019

Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]

Stock Option Plan

10. STOCK OPTION PLAN

2005 and 2015 Plans

The Company granted incentive stock options (ISOs) and non-statutory stock options (NSOs) pursuant to its 2005 Stock Option Plan (the 2005 Plan) until the Board of Directors approved the 2015 Stock Option Plan (the 2015 Plan), and all remaining shares available for future award under the 2005 Plan were transferred to the 2015 Plan and the 2005 Plan was terminated. The Company granted ISOs and NSOs pursuant to its 2015 Plan until the 2017 Equity Incentive Plan (the 2017 Plan) was approved by the Board of Directors and became effective on October 11, 2017. As a result of the 2017 Plan becoming effective, all remaining shares available for future award under the 2015 Plan were transferred to the 2017 Plan, the 2015 Plan was terminated, and no further grants will be made under the Company’s 2005 Plan and the 2015 Plan. Any outstanding stock awards granted under the 2005 Plan and the 2015 Plan will remain outstanding, subject to the terms of the Company’s 2005 Plan and 2015 Plan and the applicable stock award agreements, until such outstanding stock awards that are stock options are exercised or until they terminate or expire by their terms, or until such stock awards are fully settled, terminated or forfeited.

2017 Plan

The Company’s 2017 Plan provides for the grant of ISOs, 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.

The Company recognized stock-based compensation for its employees and non-employees in the accompanying consolidated statements of operations as follows:

	Three Months Ended
	March 31,
	2019		2018
Cost of revenue	$	9	$	4
Sales and marketing		135		22
Research and development		24		15
General and administrative		180		84
Total stock-based compensation	$	348	$	125

Stock Options

The fair value of each option is estimated at the date of grant using the Black-Scholes-Merton option pricing model, based on the following assumptions:

	Three Months Ended
	March 31,
	2019	2018
Expected term (years)	5.1	6.1
Risk-free interest rate	2.65%	2.40%
Expected volatility	60.00%	55.50%
Dividend yield	0%	0%

The following table summarizes stock option activity under the Company’s stock option plan:

						Weighted-
				Weighted-		Average
				Average		Remaining		Aggregate
	Number of			Exercise Price		Contractual		Intrinsic
	Shares			per Share		Term		Value
Outstanding — December 31, 2018		3,989,432		$	1.95		8.7	$	—
Options granted		20,000			0.83
Options cancelled		(38,919	)		1.37
Outstanding — March 31, 2019		3,970,513		$	1.95		8.3	$	—
Vested and expected to vest — March 31, 2019		3,582,709		$	1.96		8.2	$	—
Exercisable — March 31, 2019		1,459,630		$	1.97		7.3	$	—

The weighted-average grant date fair value of options granted was $0.44 per share for three months ended March 31, 2019.

No options were exercised for the three months ended March 31, 2019. The total intrinsic value of options exercised was $14.8 for the three months ended March 31, 2018.

Unamortized stock-based compensation was $2,090 as of March 31, 2019, which is expected to be recognized over a weighted-average period of approximately 2.92 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 March 31, 2019, the Company had $144 of unrecognized compensation expense, net of estimated forfeitures, which it expects to recognize over the next seven months. The aggregate intrinsic value of the RSAs outstanding was $159.

Restricted Stock Units

On February 27, 2019, the Company’s Board of Directors granted our Chief Financial Officer and interim Chief Commercial Officer each 500,000 restricted stock units that will vest contingent on the closing of the merger of the Company with Venus (as discussed in Note 1). During the three months ended March 31, 2019, no stock-based compensation expense was recorded.

Summary of Significant Accounting Policies (Policies)

3 Months Ended

Mar. 31, 2019

Accounting Policies [Abstract]

Liquidity

Basis of Presentation

Principles of Consolidation

Use of Estimates

Cash, Cash Equivalents, and Restricted Cash

	March 31, 2019		December 31, 2018
Cash and cash equivalents	$	14,957	$	16,122
Restricted cash		83		83
Total cash, cash equivalents and restricted cash in the condensed consolidated statements of cash flows	$	15,040	$	16,205

Segments

Concentration of Customers

Jobs Act Accounting Election

JOBS Act Accounting Election

Recently Adopted Accounting Standards

Recently Issued Accounting Standards Not Yet Adopted

Revenue (Tables)

3 Months Ended

Mar. 31, 2019

Summary of Estimated Revenue Expected to be Recognized in Future Related to Performance Obligations Unsatisfied or Partially Unsatisfied at Period End

Revenue	2019		2020		2021		2022 and Thereafter		Total
System related	$	339	$	—	$	—	$	—	$	339
Procedure-based		238		—		—		—		238
Service-related fees		807		176		25		112		1,120
Total	$	1,384	$	176	$	25	$	112	$	1,697

Deferred Revenue (Remaining Performance Obligations)

	Three months ended March 31, 2019
Balance at the beginning of the period	$	1,661
Additions		615
Recognition of deferred revenue		(579	)
Balance at the end of the period	$	1,697
Less: Deferred revenue - current	$	1,384
Deferred revenue - non-current (A)	$	313

(A)

Included in “Other long-term liabilities” on the condensed consolidated balance sheets as of March 31, 2019.

Disaggregation of Revenue Geographic Regions and Nature of Product and Services

The following tables provide information about disaggregated revenue from contracts with customers into geographic regions, and the nature of the products and services:

	Three Months Ended
	March 31,
	2019		2018
United States	$	3,183	$	2,255
Europe and Middle East		1,115		973
Asia Pacific		688		1,104
Rest of World		408		673
Total revenue	$	5,394	$	5,005

	Three Months Ended
	March 31,
	2019		2018
Systems	$	3,553	$	2,005
Procedure-based		1,362		2,473
Service-related fees		479		527
Total revenue	$	5,394	$	5,005

Topic 606

Impact on Financial Statements in Accordance with Topic 606

In accordance with Topic 606, the disclosure of the impact of the change in accounting principle to the unaudited condensed consolidated statements of operations and balance sheets was as follows:

	Three months ended March 31, 2019
Condensed Consolidated Statements of Operations Data	As Reported			Adjustments			Balance Without ASC 606 Adoption
Revenue	$	5,394		$	(169	)	$	5,225
Gross profit		2,937			(169	)		2,768
Total operating expenses		9,551			11			9,562
Loss from operations		(6,614	)		(180	)		(6,794	)
Net loss before provision for income taxes		(7,426	)		(180	)		(7,606	)
Net loss attributable to common stockholders	$	(7,440	)	$	(180	)	$	(7,620	)
Net loss per share attributable to common stockholders, basic and diluted	$	(0.18	)	$	(0.01	)	$	(0.19	)
Weighted-average shares used in computing net loss per share attributable to common stockholders, basic and diluted		40,753,012						40,753,012

	March 31, 2019
Condensed Consolidated Balance Sheets Data	As Reported			Adjustments			Balance Without ASC 606 Adoption
Assets
Prepaid expenses and other current assets	$	1,239		$	(132	)	$	1,107
Other assets		166			(48	)		118
Stockholders' deficit
Accumulated deficit		(200,653	)		(180	)		(200,833	)

Fair Value Measurements - (Tables)

3 Months Ended

Mar. 31, 2019

Fair Value Disclosures [Abstract]

Schedule for Levels of Fair Value Measurements of Cash Equivalents

The following tables summarize the levels of fair value measurements of the Company’s cash equivalents:

	Fair Value Measurements as of March 31, 2019
	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	$	13,715	$	—	$	—	$	13,715
Restricted cash:
Money market account		83		—		—		83
Total assets	$	13,798	$	—	$	—	$	13,798

	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

Balance Sheet Components (Tables)

3 Months Ended

Mar. 31, 2019

Balance Sheet Components [Abstract]

Schedule of Inventory

Inventory consists of the following:

	March 31,		December 31,
	2019		2018
Raw materials	$	2,114	$	2,464
Work-in-process		92		323
Finished goods		3,001		2,735
Total inventory	$	5,207	$	5,522

Schedule of Property and Equipment, Net

Property and equipment, net consist of the following:

	March 31,			December 31,
	2019			2018
Equipment	$	3,844		$	3,531
Computer hardware and software		910			901
Leasehold improvements		874			874
Furniture and fixtures		457			457
Total property and equipment		6,085			5,763
Less: Accumulated depreciation and amortization		(4,614	)		(4,464	)
Total property and equipment, net	$	1,471		$	1,299

Stock Option Plan (Tables)

3 Months Ended

Mar. 31, 2019

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:

	Three Months Ended
	March 31,
	2019		2018
Cost of revenue	$	9	$	4
Sales and marketing		135		22
Research and development		24		15
General and administrative		180		84
Total stock-based compensation	$	348	$	125

Assumptions used in Fair Value of Option Estimated at Date of Grant using Black-Scholes-Merton Option Pricing Model

The fair value of each option is estimated at the date of grant using the Black-Scholes-Merton option pricing model, based on the following assumptions

	Three Months Ended
	March 31,
	2019	2018
Expected term (years)	5.1	6.1
Risk-free interest rate	2.65%	2.40%
Expected volatility	60.00%	55.50%
Dividend yield	0%	0%

Summary of Stock Option Activity

The following table summarizes stock option activity under the Company’s stock option plan:

						Weighted-
				Weighted-		Average
				Average		Remaining		Aggregate
	Number of			Exercise Price		Contractual		Intrinsic
	Shares			per Share		Term		Value
Outstanding — December 31, 2018		3,989,432		$	1.95		8.7	$	—
Options granted		20,000			0.83
Options cancelled		(38,919	)		1.37
Outstanding — March 31, 2019		3,970,513		$	1.95		8.3	$	—
Vested and expected to vest — March 31, 2019		3,582,709		$	1.96		8.2	$	—
Exercisable — March 31, 2019		1,459,630		$	1.97		7.3	$	—

Nature of Operations - Additional Information (Details) $ / shares in Units, $ in Thousands		3 Months Ended
	Mar. 15, 2019 USD ($) $ / shares shares	Mar. 31, 2019 shares	Dec. 31, 2018 shares
Nature Of Operations [Line Items]
Common stock, shares outstanding \| shares		40,677,012	40,677,012
Reverse stock split		1-for-15 reverse stock split
Merger Agreement
Nature Of Operations [Line Items]
Percentage of ownership acquired	15.00%
Common stock, shares outstanding \| shares	283,200,000
Reverse stock split conversion ratio	0.0667
Merger Agreement \| Reverse Stock Split
Nature Of Operations [Line Items]
Common stock, shares outstanding \| shares	18,900,000
Merger Agreement \| Venus
Nature Of Operations [Line Items]
Percentage of ownership acquired	85.00%
Merger Agreement \| EW Healthcare Partners
Nature Of Operations [Line Items]
Equity method investments amount \| $	$ 21,000
Equity method investment price per share \| $ / shares	$ 0.825
Unsecured Convertible Promissory Notes \| Third Amendment
Nature Of Operations [Line Items]
Amount of convertible promissory notes \| $	$ 5,000
Unsecured Convertible Promissory Notes \| Merger Agreement \| Fred Moll and Inter West Partners
Nature Of Operations [Line Items]
Amount of convertible promissory notes \| $	$ 5,000
Conversion price of convertible promissory notes \| $ / shares	$ 0.825

Revenue - Impact on Financial Statements in Accordance with Topic 606 (Income Statement) (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Revenue Initial Application Period Cumulative Effect Transition [Line Items]
Revenue	$ 5,394	$ 5,005
Gross profit	2,937	1,820
Total operating expenses	9,551	8,860
Loss from operations	(6,614)	(7,040)
Net loss before provision for income taxes	(7,426)	(7,418)
Net loss attributable to common stockholders	$ (7,440)	$ (7,431)
Net loss per share attributable to common stockholders, basic and diluted	$ (0.18)	$ (0.26)
Weighted-average shares used in computing net loss per share attributable to common stockholders, basic and diluted	40,753,012	28,962,269
Adjustments \| Topic 606
Revenue Initial Application Period Cumulative Effect Transition [Line Items]
Revenue	$ (169)
Gross profit	(169)
Total operating expenses	11
Loss from operations	(180)
Net loss before provision for income taxes	(180)
Net loss attributable to common stockholders	$ (180)
Net loss per share attributable to common stockholders, basic and diluted	$ (0.01)
Balance Without ASC 606 Adoption \| Topic 606
Revenue Initial Application Period Cumulative Effect Transition [Line Items]
Revenue	$ 5,225
Gross profit	2,768
Total operating expenses	9,562
Loss from operations	(6,794)
Net loss before provision for income taxes	(7,606)
Net loss attributable to common stockholders	$ (7,620)
Net loss per share attributable to common stockholders, basic and diluted	$ (0.19)
Weighted-average shares used in computing net loss per share attributable to common stockholders, basic and diluted	40,753,012

Balance Sheet Components - Schedule of Property and Equipment, Net (Details) - USD ($) $ in Thousands	Mar. 31, 2019	Dec. 31, 2018
Property Plant And Equipment [Abstract]
Equipment	$ 3,844	$ 3,531
Computer hardware and software	910	901
Leasehold improvements	874	874
Furniture and fixtures	457	457
Total property and equipment	6,085	5,763
Less: Accumulated depreciation and amortization	(4,614)	(4,464)
Total property and equipment, net	$ 1,471	$ 1,299

Commitments and Contingencies - Additional Information (Details) $ in Thousands	1 Months Ended		3 Months Ended
	Feb. 29, 2012 USD ($)	Jul. 31, 2006 USD ($) shares	Mar. 31, 2019 USD ($) ft² Agreement Complaint	Dec. 31, 2018 USD ($)	Mar. 31, 2018 USD ($)
Commitment And Contingencies [Line Items]
Rent expense			$ 163		$ 103
Charge related to excess purchase commitments				$ 188
Loss contingency accrual			$ 473
Number of complaints filed \| Complaint			2
Rassman Licensing, LLC
Commitment And Contingencies [Line Items]
License agreement termination date		May 09, 2020
Rassman Licensing, LLC \| License Agreement
Commitment And Contingencies [Line Items]
One time payment of royalty related to license	$ 400	$ 1,000
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
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. 01, 2016
Master agreement for purchase of kits used with robotic device, effective date			Mar. 01, 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			$ 285
San Jose, California
Commitment And Contingencies [Line Items]
Operating lease office space area \| ft²			23,000
Operating lease manufacturing space area \| ft²			2,500
Operating lease expiration date of office space area			2022-04

Long-Term Debt - Additional Information (Details)			1 Months Ended	3 Months Ended
Long-Term Debt - Additional Information (Details)	Feb. 28, 2019 USD ($) ConvertiblePromissoryNote	Nov. 02, 2018 USD ($) $ / shares shares	May 31, 2018 USD ($)	Mar. 31, 2019 USD ($) $ / shares shares	Feb. 13, 2019 USD ($)	Dec. 31, 2018 $ / shares
Debt Instrument [Line Items]
Common stock, par value \| $ / shares				$ 0.0001		$ 0.0001
Loan and Security Agreement
Debt Instrument [Line Items]
Debt instrument, borrowed amount			$ 20,000,000
Debt Instrument, full repayment date				May 01, 2022
Debt instrument, term			4 years
Proceeds from loan used to repay debt			$ 10,085,000
Debt instrument, final payment amount upon maturity			1,300,000
Debt instrument, outstanding balance repaid			8,667,000
Debt instrument accrued interest and prepayment fees			$ 118,000
Debt instrument, outstanding balance				$ 20,000,000
Debt instrument, accrued interest				$ 180,000
Debt instrument, interest rate				10.10%
Debt instrument, interest only period				Dec. 01, 2019
Loan and Security Agreement \| LIBOR
Debt Instrument [Line Items]
Debt instrument, basis spread on variable rate			7.95%
Loan and Security Agreement \| Maximum
Debt Instrument [Line Items]
Debt instrument, additional interest only period				3 months
8% Unsecured Convertible Promissory Notes \| Note Purchase Agreement
Debt Instrument [Line Items]
Debt instrument, borrowed amount	$ 5,000,000
Number of convertible promissory notes issued \| ConvertiblePromissoryNote	2
Debt Instrument, full repayment date	Aug. 28, 2020
Debt instrument, interest rate, stated percentage	8.00%
Accrued interest				$ 35,000,000
8% Unsecured Convertible Promissory Notes \| Note Purchase Agreement \| Minimum
Debt Instrument [Line Items]
Gross proceeds from conversion of convertable securities	$ 20,000,000
Loan and Security Agreement
Debt Instrument [Line Items]
Debt conversion, warrants issued \| shares		161,725		161,725
Common stock, par value \| $ / shares		$ 0.0001		$ 0.0001
Exercise price of warrants \| $ / shares		$ 1.76		$ 3.71
Debt instrument, term				10 years
Fair value of warrants issued				$ 404,000
Debt instrument transaction cost related amount				$ 404,000
Fee paid to lenders		$ 50,000
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				$ 505,000
Loan and Security Agreement \| Measurement Input, Share Price
Debt Instrument [Line Items]
Warrants and Rights Outstanding, Measurement Input \| $ / shares				3.71
Loan and Security Agreement \| Measurement Input, Exercise Price
Debt Instrument [Line Items]
Warrants and Rights Outstanding, Measurement Input \| $ / shares				3.71
Loan and Security Agreement \| Measurement Input, Risk Free Interest Rate
Debt Instrument [Line Items]
Warrants and Rights Outstanding, Measurement Input				0.0297
Loan and Security Agreement \| Measurement Input, Price Volatility
Debt Instrument [Line Items]
Warrants and Rights Outstanding, Measurement Input				0.5550
Loan and Security Agreement \| Measurement Input, Expected Term
Debt Instrument [Line Items]
Debt instrument, term				10 years
Loan and Security Agreement \| Measurement Input, Expected Dividend Rate
Debt Instrument [Line Items]
Warrants and Rights Outstanding, Measurement Input				0.00
Loan and Security Agreement \| Third Amendment
Debt Instrument [Line Items]
Debt instrument final fee payable increased amount					$ 960,000

Long-Term Debt - Schedule Principal Payments on Outstanding Borrowings (Details) - USD ($) $ in Thousands	Mar. 31, 2019	Dec. 31, 2018
Debt Disclosure [Abstract]
2019 (remaining 9 months)	$ 667
2020	13,000
2021	8,000
2022	4,293
Total	25,960
Less debt discount	(1,331)
Less current portion	(1,974)	$ (49)
Non-current portion	22,655
Convertible promissory notes	5,000
Long-term debt	17,655	$ 19,418
Total non-current portion	$ 22,655

Stock Option Plan - Additional Information (Details) - USD ($)				3 Months Ended
	Feb. 27, 2019	Nov. 01, 2018	Oct. 11, 2017	Mar. 31, 2019	Mar. 31, 2018
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Weighted-average grant date fair value of options granted				$ 0.44
Number of Shares, Options exercised				0
Total intrinsic value of options exercised					$ 14,800
Unamortized stock-based compensation				$ 2,090,000
Unamortized stock-based compensation, weighted-average period				2 years 11 months 1 day
Stock-based compensation				$ 348,000	$ 125,000
Restricted Stock Awards
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Unrecognized compensation expense, net of estimated forfeitures				$ 144,000
Expense recognition period				7 months
Aggregate intrinsic value of the RSUs outstanding				$ 159,000
Restricted Stock Unit
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Stock-based compensation				$ 0
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
Keith Sullivan \| Restricted Stock Unit
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Number of stock awards granted	500,000
Chief Financial Officer \| Restricted Stock Unit
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Number of stock awards granted	500,000
2017 Plan
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Effective date of plan			Oct. 11, 2017

Stock Option Plan - Summary of Stock Option Activity (Details) - $ / shares	3 Months Ended	12 Months Ended
	Mar. 31, 2019	Dec. 31, 2018
Share Based Compensation Arrangement By Share Based Payment Award Options Outstanding Roll Forward
Number of Shares, Outstanding, Beginning Balance	3,989,432
Number of Shares, Options granted	20,000
Number of Shares, Options cancelled	(38,919)
Number of Shares, Outstanding, Ending Balance	3,970,513	3,989,432
Number of Shares, Vested and expected to vest	3,582,709
Number of Shares, Exercisable	1,459,630
Weighted-Average Exercise Price Per Share, Outstanding, Beginning Balance	$ 1.95
Weighted-Average Exercise Price Per Share, Options granted	0.83
Weighted-Average Exercise Price Per Share, Options cancelled	1.37
Weighted-Average Exercise Price Per Share, Outstanding, Ending Balance	1.95	$ 1.95
Weighted-Average Exercise Price Per Share, Vested and expected to vest	1.96
Weighted-Average Exercise Price Per Share, Exercisable	$ 1.97
Weighted-Average Remaining Contractual Term, Outstanding	8 years 3 months 18 days	8 years 8 months 12 days
Weighted-Average Remaining Contractual Term, Vested and expected to vest	8 years 2 months 12 days
Weighted-Average Remaining Contractual Term, Exercisable	7 years 3 months 18 days

Summary of Significant Accounting Policies - Additional Information (Details)		3 Months Ended		12 Months Ended
	Jan. 01, 2019 USD ($)	Mar. 31, 2019 USD ($) Customer Segment	Mar. 31, 2018 Customer	Dec. 31, 2018 USD ($) Customer
Summary Of Significant Accounting Policies [Line Items]
Accumulated deficit \| $		$ (200,653,000)		$ (193,213,000)
Number of operating segments \| Segment		1
Number of reportable segments \| Segment		1
Cumulative-effect adjustment to accumulated deficit \| $	$ 0
Customer Concentration Risk \| Revenue
Summary Of Significant Accounting Policies [Line Items]
Number of major customers \| Customer		1	0
Concentration Risk, Percentage		10.00%	10.00%
Customer Concentration Risk \| Accounts Receivable
Summary Of Significant Accounting Policies [Line Items]
Number of major customers \| Customer		0		0
Concentration Risk, Percentage		10.00%		10.00%

Revenue - Additional Information (Details) $ in Thousands	3 Months Ended
Revenue - Additional Information (Details) $ in Thousands	Mar. 31, 2019 USD ($)
Disaggregation Of Revenue [Line Items]
Revenue performace obligation, description of payment terms	Payment terms for U.S. customers are generally at shipment, delivery, or within 30 day of shipment, while payment terms for customers outside of the U.S. vary between 30 and 180 days after shipment.
Remaining performance obligations description	one year or less
ARTAS Systems \| Prepaid and Other Current Assets
Disaggregation Of Revenue [Line Items]
Unamortized deferred compensation assets, short term	$ 3
ARTAS Systems \| Other Assets
Disaggregation Of Revenue [Line Items]
Unamortized deferred compensation assets, long term	$ 8

Revenue - Additional Information (Details1) - Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date: 2019-04-01	Mar. 31, 2019
Minimum
Disaggregation Of Revenue [Line Items]
Revenue, remaining performance obligation, expected timing of Satisfaction, period	30 days
Maximum
Disaggregation Of Revenue [Line Items]
Revenue, remaining performance obligation, expected timing of Satisfaction, period	180 days

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	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Total potential dilutive shares	4,242,724	2,257,309
Options to Purchase Common Stock
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Total potential dilutive shares	3,970,513	1,950,853
Warrants for Common Stock
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Total potential dilutive shares	272,211	306,456

Common Stock Reserved for Issuance - Schedule of Common Stock Reserved for Issuance (Details) - shares	Mar. 31, 2019	Dec. 31, 2018
Class Of Stock [Line Items]
Outstanding and issued stock options	3,970,513	3,989,432
Shares reserved for future option grants	1,069,271	437,241
Total common stock reserved for issuance	5,311,995	4,698,884
Common Stock
Class Of Stock [Line Items]
Outstanding common stock warrants	272,211	272,211

Condensed Consolidated Statements of Comprehensive Loss (Unaudited) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Statement Of Income And Comprehensive Income [Abstract]
Net loss	$ (7,440)	$ (7,431)
Other comprehensive income (loss):
Cumulative translation adjustment	36	4
Comprehensive loss	$ (7,404)	$ (7,427)

Revenue - Impact on Financial Statements in Accordance with Topic 606 (Balance Sheet) (Details) - USD ($) $ in Thousands	Mar. 31, 2019	Dec. 31, 2018
ASSETS
Prepaid expenses and other current assets	$ 1,239	$ 1,278
Other assets	166	100
Stockholders' deficit
Accumulated deficit	(200,653)	$ (193,213)
Adjustments \| Topic 606
ASSETS
Prepaid expenses and other current assets	(132)
Other assets	(48)
Stockholders' deficit
Accumulated deficit	(180)
Balance Without ASC 606 Adoption \| Topic 606
ASSETS
Prepaid expenses and other current assets	1,107
Other assets	118
Stockholders' deficit
Accumulated deficit	$ (200,833)

Revenue - Summary of Estimated Revenue Expected to be Recognized in Future Related to Performance Obligations Unsatisfied or Partially Unsatisfied at Period End (Details) $ in Thousands	Mar. 31, 2019 USD ($)
Disaggregation Of Revenue [Line Items]
2019	$ 1,384
2020	176
2021	25
2022 and Thereafter	112
Total	1,697
System Related
Disaggregation Of Revenue [Line Items]
2019	339
Total	339
Procedure- Based
Disaggregation Of Revenue [Line Items]
2019	238
Total	238
Service-Related Fees
Disaggregation Of Revenue [Line Items]
2019	807
2020	176
2021	25
2022 and Thereafter	112
Total	$ 1,120

Fair Value Measurements - Schedule for Levels of Fair Value Measurements of Cash Equivalents - (Details) - USD ($) $ in Thousands	Mar. 31, 2019	Dec. 31, 2018
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Total assets	$ 13,798	$ 14,051
Quoted Prices in Active Markets using Identical Assets (Level 1)
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Total assets	13,798	14,051
Money Market Account
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Cash Equivalents	13,715	13,968
Restricted cash	83	83
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	13,715	13,968
Restricted cash	$ 83	$ 83

Balance Sheet Components - Schedule of Inventory (Details) - USD ($) $ in Thousands	Mar. 31, 2019	Dec. 31, 2018
Inventory Disclosure [Abstract]
Raw materials	$ 2,114	$ 2,464
Work-in-process	92	323
Finished goods	3,001	2,735
Total inventory	$ 5,207	$ 5,522

Commitments and Contingencies - Summary of Aggregate Future Minimum Lease Payments under Operating Leases (Details) $ in Thousands	Mar. 31, 2019 USD ($)
Commitments And Contingencies Disclosure [Abstract]
2019 (remaining 9 months)	$ 389
2020	534
2021	550
2022	188
Total future minimum lease payments	$ 1,661

Income Taxes - Additional Information (Details) - USD ($)	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Income Tax Disclosure [Abstract]
Provision for income taxes	$ 14,000	$ 13,000
Effective income tax rate	(0.19%)	(0.17%)
Effective income tax rate, expected rate for fiscal year		(0.17%)
Unrecognized tax benefits	$ 1,490,000
Interest and penalties related to uncertain tax positions	$ 0