0000950170-22-002903 | 10-K | XBRL Viewer | Treace Medical Concepts INC

Balance Sheets - USD ($) $ in Thousands	Dec. 31, 2021	Dec. 31, 2020
Current assets
Cash and cash equivalents	$ 105,833	$ 18,079
Accounts receivable, net of allowance for doubtful accounts of $414 and $446 as of December 31, 2021 and 2020, respectively	18,568	14,486
Inventories	10,561	7,820
Prepaid expenses and other current assets	3,010	593
Total current assets	137,972	40,978
Property and equipment, net	2,849	829
Total assets	140,821	41,807
Current liabilities
Accounts payable	4,056	2,265
Accrued liabilities	4,518	1,848
Accrued commissions	5,181	3,513
Accrued compensation	4,455	2,183
Short-term debt		1,788
Total current liabilities	18,210	11,597
Derivative liability on term loan	173	245
Long-term debt, net of discount of $635 and $811 as of December 31, 2021 and 2020, respectively	29,365	29,189
Total liabilities	47,748	41,031
Commitments and contingencies (Note 7)
Stockholders’ equity
Additional paid-in capital	134,933	14,166
Accumulated deficit	(41,905)	(21,353)
Total stockholders’ equity	93,073	776
Total liabilities and stockholders’ equity	140,821	41,807
Series A Convertible Preferred Stock [Member]
Stockholders’ equity
Preferred stock, value		7,935
Preferred Stock [Member]
Stockholders’ equity
Preferred stock, value
Common Stock [Member]
Stockholders’ equity
Common stock, value	$ 45	$ 28

Balance Sheets (Parenthetical) - USD ($) $ in Thousands	Dec. 31, 2021	Dec. 31, 2020
Allowance for doubtful accounts receivable current	$ 414	$ 446
Long term debt unamortized debt discount and issuance costs	$ 635	$ 811
Preferred stock, shares outstanding	0
Series A Convertible Preferred Stock [Member]
Preferred stock, par or stated value per share	$ 0.001	$ 0.001
Preferred stock shares authorized	0	6,687,500
Preferred stock, shares issued	0	6,687,475
Preferred stock, shares outstanding	0	6,687,475
Preferred stock, liquidation preference, value	$ 0	$ 8,000
Preferred Stock [Member]
Preferred stock, par or stated value per share	$ 0.001	$ 0.001
Preferred stock shares authorized	5,000,000	0
Preferred stock, shares issued	0	0
Preferred stock, shares outstanding	0	0
Common Stock [Member]
Common stock, par or stated value per share	$ 0.001	$ 0.001
Common stock shares authorized	300,000,000	66,875,000
Common stock share issued	54,181,082	37,366,865
Common stock share outstanding	54,181,082	37,366,865
Common Class B [Member]
Common stock, par or stated value per share	$ 0.001	$ 0.001
Common stock shares authorized	0	1,000,000
Common stock share issued	0	0
Common stock share outstanding	0	0

Statements of Operations and Comprehensive Loss - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Income Statement [Abstract]
Revenue	$ 94,419	$ 57,365	$ 39,416
Cost of goods sold	17,826	12,470	7,631
Gross profit	76,593	44,895	31,785
Operating expenses
Sales and marketing	64,467	31,654	25,786
Research and development	10,204	5,847	5,070
General and administrative	18,432	6,539	4,464
Total operating expenses	93,103	44,040	35,320
Income (loss) from operations	(16,510)	855	(3,535)
Interest and other income (expense), net	18	(1,746)	111
Interest expense	(4,060)	(2,777)	(841)
Other expense, net	(4,042)	(4,523)	(730)
Net loss and comprehensive loss	(20,552)	(3,668)	(4,265)
Convertible preferred stock cumulative and undeclared dividends	(196)	(640)	(640)
Net loss attributable to common stockholders	$ (20,748)	$ (4,308)	$ (4,905)
Net loss per share attributable to common stockholders, basic and diluted	$ (0.43)	$ (0.12)	$ (0.13)
Weighted-average shares used in computing net loss per share attributable to common stockholders, basic and diluted	48,415,679	37,068,965	36,911,586

Statements of Stockholders' Equity - USD ($) $ in Thousands	Total	Convertible preferred stock [Member]	Common Stock [Member]	Additional Paid-in Capital [Member]	Accumulated Deficit [Member]
Balance at Beginning at Dec. 31, 2018	$ 5,948	$ 7,935	$ 27	$ 11,407	$ (13,421)
Balance at Beginning (in Shares) at Dec. 31, 2018		6,687,475	36,771,697
Issuance of warrants for Class A common stock in connection with Credit Facility (Note 9)	595			595
Common stock issued upon exercise of stock options	68		$ 1	67
Common stock issued upon exercise of stock options, shares			260,144
Share-based compensation expense	815			815
Net loss	(4,265)				(4,265)
Balance at Ending at Dec. 31, 2019	3,161	$ 7,935	$ 28	12,884	(17,686)
Balance at Ending (in Shares) at Dec. 31, 2019		6,687,475	37,031,841
Common stock issued upon exercise of stock options	364			364
Common stock issued upon exercise of stock options, shares			335,025
Share-based compensation expense	919			919
Net loss	(3,668)				(3,668)
Balance at Ending at Dec. 31, 2020	776	$ 7,935	$ 28	14,167	(21,353)
Balance at Ending (in Shares) at Dec. 31, 2020		6,687,475	37,366,865
Common stock issued upon exercise of stock options	$ 1,830		$ 2	1,828
Common stock issued upon exercise of stock options, shares	2,368,705		2,368,705
Issuance of restricted stock awards, shares			24,895
Share-based compensation expense	$ 3,409			3,409
Issuance of common stock from initial public offering, net of issuance costs and underwriting discount of $10.6 million	107,610		$ 7	107,603
Issuance of common stock from initial public offering, net of issuance costs and underwriting discount of $10.6 million, shares			6,953,125
Issuance of common stock upon net exercise of warrants			$ 1	(1)
Issuance of common stock upon net exercise of warrants, shares			621,570
Conversion of convertible preferred stock and accrued dividends on convertible preferred stock into common stock		$ (7,935)	$ 7	7,928
Conversion of convertible preferred stock and accrued dividends on convertible preferred stock into common stock, shares		(6,687,475)	6,845,922
Net loss	(20,552)				(20,552)
Balance at Ending at Dec. 31, 2021	$ 93,073		$ 45	$ 134,934	$ (41,905)
Balance at Ending (in Shares) at Dec. 31, 2021			54,181,082

Statements of Cash Flows - USD ($) $ in Thousands	12 Months Ended
Statements of Cash Flows - USD ($) $ in Thousands	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Cash flows from operating activities
Net loss	$ (20,552)	$ (3,668)	$ (4,265)
Adjustments to reconcile net loss to net cash used in operating activities
Depreciation and amortization expense	685	1,210	793
Provision for allowance for doubtful accounts	144	216	145
Share-based compensation expense	3,409	919	815
Amortization of debt issuance costs	176	220	147
Impairment of capitalized surgical instruments		144
Gain on fair value adjustment to derivative liability	(72)
Provision for inventory obsolescence	347	1,144
Loss on early settlement of debt		639
Net changes in operating assets and liabilities:
Accounts Receivable	(4,226)	(4,290)	(6,022)
Inventory	(3,088)	(3,402)	(2,813)
Prepaid expenses and other assets	(2,417)	(103)	(94)
Accounts payable	1,791	1,334	(236)
Accrued liabilities	6,610	1,143	3,857
Net cash used in operating activities	(17,193)	(4,494)	(7,673)
Cash flows from investing activities
Purchases of property and equipment	(2,705)	(1,069)	(1,211)
Net cash used in investing activities	(2,705)	(1,069)	(1,211)
Cash flows from financing activities
Proceeds from interest bearing debt		29,530	20,000
Payments on interest bearing debt		(20,000)
Proceeds from PPP Loan		1,788
Repayments on PPP Loan	(1,788)
Proceeds from issuance of common stock upon initial public offering, net of issuance costs and underwriting fees of $10.6 million	107,610
Debt issuance costs		(179)	(329)
Proceeds from exercise of employee stock options	1,830	364	68
Net cash provided by financing activities	107,652	11,503	19,739
Net increase in cash and cash equivalents	87,754	5,940	10,855
Cash and cash equivalents at beginning of period	18,079	12,139	1,284
Cash and cash equivalents at end of period	105,833	18,079	12,139
Supplemental disclosure of cash flow information:
Cash paid for interest	3,900	1,146	739
Noncash financing activities:
Issuance of warrants for Class A common stock in connection with the Company’s Credit Facility			$ 595
Issuance of common stock upon exercise of warrants	1
Conversion of convertible preferred stock and accrued dividends on convertible preferred stock into common stock	$ 7,935
Initial fair value of derivative liability		$ 245

Summary of Significant Accounting Policies

12 Months Ended

Dec. 31, 2021

Accounting Policies [Abstract]

Summary of Significant Accounting Policies

2. Summary of Significant Accounting Policies

Basis of Presentation

The accompanying financial statements have been prepared using accounting principles generally accepted in the United States of America (“GAAP”), as defined by the Financial Accounting Standards Board, or the FASB.

Use of Estimates

The preparation of financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities at the date of the financial statements and the reported amounts of revenues and expenses during the periods presented. Although these estimates are based on the Company’s knowledge of current events and actions it may undertake in the future, actual results may ultimately materially differ from these estimates and assumptions.

Significant estimates and assumptions include reserves and write-downs related to accounts receivable, inventories, the recoverability of long-term assets, valuation of equity instruments, valuation of common stock, stock-based compensation, deferred tax assets and related valuation allowances and impact of contingencies. The Company had no accrued contingent liabilities as of December 31, 2021 and 2020.

Fair Value of Financial Instruments

The carrying amounts of the Company’s financial instruments, including cash and cash equivalents, accounts receivable, accounts payable, and accrued liabilities, approximate their fair value due to the short-term nature of these assets and liabilities. The derivative liability is carried at fair value based on unobservable market inputs. Based on the borrowing rates currently available to the Company for debt with similar terms and consideration of default and credit risk, the carrying value of the term loans approximates their fair value (Note 4).

Segments

The Company operates and manages its business as one reportable and operating segment, which is the business of designing, manufacturing, and marketing medical devices for physicians, surgeons, ambulatory surgery centers and hospitals. The Company’s chief executive officer, who is the chief operating decision maker, reviews financial information on an aggregate basis for purposes of allocating and evaluating financial performance. All long-lived assets are maintained in the United States.

Cash and Cash Equivalents

The Company considers all highly liquid investments with an original or remaining maturity of three months or less at the time of purchase to be cash equivalents, which include money market funds.

Accounts Receivable and Allowances

Accounts receivable are generally from hospitals and ambulatory surgery centers and are stated at amounts billed less allowances for doubtful accounts. The Company continually monitors customer payments and maintains an allowance for losses resulting from a customer’s inability to make required payments. The Company considers factors such as historical experience, credit quality, age of the accounts receivable balances, geographic related risks and economic conditions that may affect a customer’s ability to pay. Accounts receivable are written off when individual balances are no longer collectible. As of December 31, 2021 and 2020, accounts receivable is presented net of an allowance for doubtful accounts of $0.4 million in both years. For the years ended December 31, 2021, 2020 and 2019, the Company recorded provision for bad debts of $0.1 million, $0.2 million and $0.1 million, respectively.

Concentration of Credit Risk

Financial instruments that potentially subject the Company to concentrations of risk consist principally of cash, cash equivalents and accounts receivable. The Company maintains its cash and cash equivalents balances with established financial institutions and, at times, such balances with any one financial institution may be in excess of the Federal Deposit Insurance Corporation (“FDIC”) insured limits.

The Company earns revenue from the sale of its products to customers such as hospitals and ambulatory surgery centers. The Company’s accounts receivable is derived from revenue earned from customers. The Company performs ongoing credit evaluations of its customers’ financial condition and generally requires no collateral from its customers and independent sales agencies. At December 31, 2021 and 2020, no customer accounted for more than 10% of accounts receivable. For the years ended December 31, 2021, 2020 and 2019, there were no customers that represented 10% or more of revenue.

Inventories

Inventories consist primarily of surgical kits and components as finished goods and are stated at the lower of cost or net realizable value. Cost is determined based on an average cost method which approximates the first-in, first-out basis and includes primarily outsourced manufacturing costs and direct manufacturing overhead costs. The Company reviews inventory for obsolescence and writes down inventory, as necessary. For the years ended December 31, 2021, 2020 and 2019, the Company recorded a provision of $0.3 million, $1.1 million and $0.1 million, respectively, for obsolete inventory to cost of goods sold.

Property and Equipment, Net

Property and equipment is recorded at cost. Depreciation of property and equipment is recorded using the straight-line method over the following estimated useful lives as follows:


		Years
Furniture, fixtures and equipment		7
Machinery and equipment		3
Capitalized surgical instruments		3
Computer equipment		3
Leasehold improvements		5 or lease term, whichever is shorter
Software		3

Long-lived assets are evaluated whenever a change in circumstances indicates that the carrying amount of an asset may not be recoverable. If assets are considered to be impaired, a charge is recorded for an amount that the carrying value exceeds the fair value. The Company recorded impairment charges for its property and equipment, net of $0 for the year ended December 31, 2021 and 2019, and $0.1 million for the year ended December 31, 2020.

Beginning January 1, 2021, the Company adjusted the useful life of its capitalized instruments from 18 months to 36 months to align with the expected life of the instruments. The change in useful life was made as a prospective adjustment and resulted in a decrease of depreciation expense of $0.3 million during the year ended December 31, 2021 and no material impact on earnings per share. The change in useful life is not expected to significantly impact annual depreciation expense.

Leases

The Company leases certain office spaces which are classified as operating leases under Accounting Standards Codification ("ASC") 840, Leases. Rent expense is recognized on a straight-line basis over the term of the lease and, accordingly, the difference between cash rent payments and the rent expense is recorded as deferred rent liability and is accrued within accrued expenses and other liabilities.

Revenue Recognition

The Company generates revenue through the sale of its primary product, the Lapiplasty System, the new Adductoplasty and Lapiplasty Mini-Incision Systems and ancillary products. The Lapiplasty and Adductoplasty Systems are comprised of single-use implant kits and reusable instrument trays. Implant kits and ancillary products are sold in the United States through a combination of a direct employee sales force and independent sales agencies. The Company invoices hospitals and ambulatory surgery centers for the

implant kits and ancillary products and pays commissions to the sales representatives and independent sales agencies. The Company has no international sales.

For shipments to customers, the Company offers the right to return the product within 30 days for a full refund, and for returns between 30 and 90 days, the Company offers a full refund less 15% restocking fee. The Company does not have a history of product returns for refund. Customer invoices are generally payable within 30 days. The Company’s products are generally sold with a limited standard warranty to the original purchaser of the products against defects in workmanship and materials for 180 days. The Company’s liability is limited to providing, at the Company’s option, a full refund or credit of the purchase price, or repairing or replacing the product, provided that the customer returns the defective product within 180 days from the purchase date. To date, the Company has had negligible returns of any products alleged to be defective.

On January 1, 2019, the Company adopted ASC 606, Revenue from Contracts with Customers, using the modified retrospective method for all contracts not completed as of the date of adoption. In connection with the adoption of ASC 606, the Company also adopted the related amendments that impact the accounting for the incremental costs of obtaining a contract. Adoption of ASC 606 did not have any impact on the financial statements, except changes in the disclosures.

Under ASC 606, revenue is recognized when the customer obtains control of promised goods or services, in an amount that reflects consideration which the entity expects to receive in exchange for those goods or services. To determine revenue recognition for arrangements that an entity determines are within the scope of ASC 606, the Company performs the following five steps as prescribed by ASC 606:

(i)

identify the contract(s) with a customer;

(ii)

identify the performance obligations in the contract;

(iii)

determine the transaction price;

(iv)

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

(v)

recognize revenue when (or as) the entity satisfies performance obligations.

A contract with a customer exists when (i) the Company enters into a legally enforceable contract with a customer that defines each party’s rights regarding the products to be transferred and identifies the payment terms related to these products, (ii) the contract has commercial substance and, (iii) the Company determines that collection of substantially all consideration for its products that are transferred is probable based on the customer’s intent and ability to pay the promised consideration. The Company considers signed agreements and purchase orders as a customer’s contract.

The Company identifies performance obligations based on the terms of the contract and customary business practices, which include products that are distinct, or a series of distinct goods that are substantially the same and that have the same pattern of transfer to the customer. The Company’s Lapiplasty System products are distinct performance obligations. The Company does not have any contracts with customers that contain multiple performance obligations.

The transaction price in the Company’s customer contracts includes fixed consideration to be contractually billed to the customer while variable consideration includes the right of return. The Company does not allocate the transaction price or any variable consideration to the right of return. The Company did not recognize a refund liability as of December 31, 2021 and 2020 and there were no product returns during the years ended December 31, 2021, 2020 and 2019.

Revenue for products is recognized when a customer obtains control of the promised products, which is generally when the customer has the ability to (i) direct its use and (ii) obtain substantially all of the remaining benefits from it. The Company consigns products with its independent sales agencies but does not recognize revenue at the time the product is transferred on consignment. Revenue recognition occurs when control of the product transfers to the customer which is generally at the time the product is used in surgery. When a customer purchases products directly from us before the time of surgery, revenue is recognized upon shipment based on the contract terms.

Contract Costs

The Company applies the practical expedient to recognize the incremental costs of obtaining a contract as expense when incurred if the amortization period would be one year or less. These incremental costs include sales commissions paid to the Company’s independent sales agencies or internal sales representatives.

Cost of Goods Sold

Cost of goods sold consists primarily of costs for the purchase of the Company’s Lapiplasty and Adductoplasty Systems as well as ancillary products from third-party manufacturers. Direct costs from the Company’s third-party manufacturers includes costs for raw materials plus the markup for the assembly of the components. Cost of goods sold also includes royalties, allocated overhead for indirect labor, depreciation, certain direct costs such as those incurred for shipping our products and personnel costs. The Company expenses all inventory provisions for excess and obsolete inventories as cost of goods sold. The Company records adjustments to its inventory valuation for estimated excess, obsolete and non-sellable inventories based on assumptions about future demand, past usage, changes to manufacturing processes and overall market conditions.

Research and Development Expenses

Research and development ("R&D") expenses consist primarily of engineering, product development, clinical studies to develop and support the Company’s products, regulatory expenses, and other costs associated with products and technologies that are in development. These expenses include compensation for personnel, including salaries, bonuses, benefits and stock-based compensation, supplies, consulting, prototyping, testing, materials, travel expenses, depreciation and an allocation of facility overhead expenses.

Shipping and Handling

The Company bills customers for shipping and handling costs. Amounts billed for shipping and handling are included in revenue. Shipping and handling costs incurred by the Company are included in marketing and sales expenses.

Advertising Costs

Advertising costs are expensed as incurred and are included as a component of marketing and sales expenses. Advertising expense includes the cost of advertising across the various mediums we employ, including print, digital, radio and television. Advertising costs totaled approximately $13.02 million, $3.1 million and $1.9 million, for the years ended December 31, 2021, 2020 and 2019, respectively.

Income Taxes

The Company accounts for income taxes under the liability method, whereby deferred tax assets and liabilities are determined based on the difference between the financial statements and tax bases of assets and liabilities using the enacted tax rates in effect for the year in which the differences are expected to affect taxable income. A valuation allowance is established when necessary to reduce deferred tax assets when management estimates, based on available objective evidence, that it is more likely than not that the benefit will not be realized for the deferred tax assets.

The Company also follows the provisions of ASC 740-10, Accounting for Uncertainty in Income Taxes. ASC 740-10, which prescribes a comprehensive model for the recognition, measurement, presentation and disclosure in financial statements of any uncertain tax positions that have been taken or expected to be taken on a tax return. No liability related to uncertain tax positions is recorded on the financial statements. It is the Company’s policy to include penalties and interest expense related to income taxes as part of the provision for income taxes.

Product Liability

The Company believes it carries adequate insurance for possible product liability claims. Accruals for product liability claims and legal defense costs in excess of insured amounts are recorded if it is probable that a liability has been incurred and the amount of any liability can be reasonably estimated. No accruals for product liability claims had been recorded as of December 31, 2021 and December 31, 2020.

Stock-Based Compensation

The Company accounts for stock-based compensation arrangements with employees in accordance with ASC 718, Compensation—Stock Compensation, using a fair-value based method. The Company determines the fair value of stock options on the date of grant using the Black-Scholes option pricing model. The fair value for RSAs and RSUs awards is the fair value at the grant date.

The fair value of time-based awards is recognized over the period during which an award holder is required to provide services in exchange for the award, known as the requisite service period, which is typically the vesting period using the straight-line method. The Company accrues for estimated forfeitures on share-based awards and, adjusts stock-based compensation cost to actual as forfeitures occur. The estimated forfeitures are based on a historical analysis of actual forfeitures of awards.

The Company estimates the fair value of the stock-based awards using the Black-Scholes option-pricing model, which requires the input of highly subjective assumptions. The assumptions are as follows:

•

Expected Term. The expected term represents the period that the stock options are expected to remain outstanding. Prior to the closing of the IPO, the Company was using the probabilities of the anticipated timing of potential liquidity events to determine the expected term. After the closing of the IPO, the Company is using the "simplified" method, which is the simple average of the vesting period and the contractual term.

•

Expected Volatility. The expected volatility is derived from the historical stock volatilities of comparable publicly listed peers over a period approximately equal to the expected term of the options as the Company does not have sufficient trading history to determine the volatility of its common stock.

•

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.

•

Expected Dividend Yield. The expected dividend yield is zero as the Company has not paid nor anticipates paying any dividends on the common stock in the foreseeable future.

•

Fair Market Value of Common Stock. Prior to the IPO, the fair market value of the common stock was determined by the board of directors with assistance from management and external valuation experts. The Company’s approach to estimating the fair market value of its common stock was consistent with the methods outlined in the American Institute of Certified Public Accountants’ Practice Aid, Valuation of Privately-Held-Company Equity Securities Issued as Compensation. Following our IPO, the fair market value of the common stock is based on its closing price on NASDAQ as reported on the date of grant.

The Company continues to use judgment in evaluating the expected volatility and expected terms utilized for the stock-based compensation calculations on a prospective basis. As the Company continues to accumulate additional data, the Company may have refinements to the assumptions, which could materially impact the future stock-based compensation expense.

Comprehensive Loss

The Company is required to report all components of comprehensive loss, including net loss, in the financial statements in the period in which they are recognized. Comprehensive loss is defined as a change in equity of a business enterprise during a period, resulting from transactions and other events and circumstances from non-owner sources. Comprehensive loss equaled net loss for the years ended December 31, 2021, 2020 and 2019.

Net Loss Per Share Attributable to Common Stockholders

Basic net loss per share attributable to common stockholders is calculated by dividing the net loss attributable to common stockholders, by the weighted-average number of common shares outstanding during the period, without consideration for potentially dilutive securities. Diluted net loss per share is computed by dividing the net loss by the weighted-average number of common shares and potentially dilutive securities outstanding for the period. For purposes of the diluted net loss per share calculation, common stock options, unvested restricted stock units and restricted stock awards are considered to be potentially dilutive securities. Because the Company has reported a net loss for the years ended December 31, 2021, 2020 and 2019, diluted net losses per common share were the same as basic net losses per common share for these periods.

Derivative Liability

The Company evaluates its financial instruments for embedded features and bifurcates embedded features from the host instrument that meet the definition of a derivative and if (a) the economic characteristics and risks of the embedded feature are not clearly and closely related to the host instrument, (b) the hybrid instrument that embodies both the embedded feature and the host contract is not remeasured at fair value under otherwise applicable generally accepted accounting principles with changes in fair value reported in earnings as they occur and (c) a separate instrument with the same terms as the embedded feature would be considered a derivative instrument subject to the accounting requirements of derivative instruments.

The Company uses judgment in determining the fair value of embedded features that are bifurcated from the host instrument and accounted for as derivative instruments at the date of issuance and at every balance sheet date thereafter. The valuation method used in

the determination of fair value is based on the type of derivative instrument. At each balance sheet date, the Company remeasures its derivative instruments at fair value with adjustments to fair value recognized within other expense, net.

Deferred Issuance Costs

Issuance costs, consisting of legal, accounting, audit, and filing fees relating to in-process equity financings, including IPO, are capitalized. Deferred issuance costs are offset against offering proceeds upon the completion of an equity financing or an offering. In the event an equity financing or an offering is terminated or delayed, deferred issuance costs will be expensed immediately as a charge to general and administrative expenses in the consolidated statements of operations and comprehensive loss. As of December 31, 2020, $0.2 million was recorded on the balance sheet. The Company had no capitalized issuance costs recorded on the balance sheet as of December 31, 2021.

Fair Value Measurements

12 Months Ended

Dec. 31, 2021

Fair Value Disclosures [Abstract]

Fair Value Measurements

4. Fair Value Measurements

Assets and liabilities recorded at fair value in the financial statements are categorized based upon the level of judgment associated with the inputs used to measure their fair value. Hierarchical levels which are directly related to the amount of subjectivity associated with the inputs to the valuation of these assets or liabilities are as follows:

Level 1—Inputs are unadjusted quoted prices in active markets for identical assets or liabilities that the Company has the ability to access as of the measurement date.

Level 2—Inputs are observable, unadjusted quoted prices in active markets for similar assets or liabilities, unadjusted quoted prices for identical or similar assets or liabilities 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 related assets or liabilities.

Level 3—Unobservable inputs for the asset or liability only used when there is little, if any, market activity for the asset or liability at the measurement date. This hierarchy requires the Company to use observable market data, when available, and to minimize the use of unobservable inputs when determining fair value.

Assets and Liabilities Measured and Recorded at Fair Value on a Recurring Basis – The following assets and liabilities are measured at fair value on a recurring basis as of December 31, 2021 and December 31, 2020:


	December 31, 2021
	Level 1		Level 2		Level 3		Total
Assets:
Money market funds(1)	$	105,220	$	—	$	—	$	105,220
Total	$	105,220	$	—	$	—	$	105,220
Liabilities:
Derivative liability	$	—	$	—	$	173	$	173
Total	$	—	$	—	$	173	$	173


	December 31, 2020
	Level 1		Level 2		Level 3		Total
Assets:
Money market funds(1)	$	17,577	$	—	$	—	$	17,577
Total	$	17,577	$	—	$	—	$	17,577
Liabilities:
Derivative liability	$	—	$	—	$	245	$	245
Total	$	—	$	—	$	245	$	245

(1)

Money market funds are included in cash and cash equivalents in the balance sheets as of December 31, 2021 and 2020.

As discussed in Note 6, in July 2020, the Company entered into the CRG Term Loan Facility and accounted for embedded features in the agreement as a derivative liability with an initial fair value of $0.2 million. The derivative liability was accounted for at fair value using the income approach and inputs consisting of (a) the probability of events occurring that trigger an event of default of the Company’s term loans under the CRG Term Loan Facility, ranging from 1% to 2%, (b) the prepayment premium payable upon early redemption, and (c) additional interest payable upon an event of default. The change in fair value of the derivative liability was $0.1 million in the year ended December 31, 2021, and was recorded as a component of other expense, net in the statements of operations and comprehensive loss. There was no adjustment to the fair value of the derivative liability recognized in net loss for the year ended December 31, 2020.

The following table sets forth a summary of the changes in the fair value of the Company’s Level 3 financial instruments (in thousands):


	Derivative liability
Fair value as of January 1, 2020	$	—
Initial fair value of derivative liability		245
Fair value as of December 31, 2020		245
Change in fair value included in other expense, net		(72	)
Fair value as of December 31, 2021	$	173

There were no assets or liabilities measured at fair value on a nonrecurring basis as of December 31, 2021 and December 31, 2020.

Balance Sheet Components

12 Months Ended

Dec. 31, 2021

Balance Sheet Related Disclosures [Abstract]

Balance Sheet Components

5. Balance Sheet Components

Cash and Cash Equivalents

The Company’s cash and cash equivalents consisted of the following (in thousands):


	December 31,
	2021		2020
Cash	$	613	$	502
Cash equivalents:
Money market funds		105,220		17,577
Total cash and cash equivalents	$	105,833	$	18,079

Property and equipment, net

The company’s property and equipment, net consisted of the following (in thousands):


	December 31,
	2021			2020
Furniture and fixtures, and equipment	$	180		$	131
Construction in progress		126			—
Machinery and equipment		274			226
Capitalized surgical equipment		4,442			2,652
Computer equipment		160			150
Leasehold improvements		268			168
Software		138			138
Total property and equipment		5,588			3,465
Less: accumulated depreciation and amortization		(2,739	)		(2,636	)
Property and equipment, net	$	2,849		$	829

Depreciation and amortization expense was $0.7 million, $1.2 million and $0.8 million for the years ended December 31, 2021, 2020 and 2019, respectively.

Accrued liabilities

Accrued liabilities consist of the following (in thousands):


	December 31,
	2021		2020
Accrued royalties expense	$	1,522	$	1,032
Accrued interest		975		—
Accrued professional services		941		375
Other accrued expense		1,080		441
Total accrued liabilities	$	4,518	$	1,848

Long Term Debt

12 Months Ended

Dec. 31, 2021

Debt Disclosure [Abstract]

Long Term Debt

6. Long Term Debt

The Company’s debt consisted of the following (in thousands):


	December 31,
	2021			2020
Revolving line of credit
SVB Credit Facility	$	—		$	—
Term loans
CRG Term Loan Facility		30,000			30,000
PPP Loan		—			1,788
Total term loans		30,000			31,788
Less: debt discount and issuance costs		(635	)		(811	)
Total debt		29,365			30,977
Short-term debt		—			1,788
Long-term debt	$	29,365		$	29,189

As of December 31, 2021, future payments under term loan were as follows (in thousands):


Fiscal Year
2022	$	—
2023		—
2024		—
2025		30,000
Total principal payments		30,000
Less: Unamortized debt discount and debt issuance costs		(635	)
Total short-term and long-term debt	$	29,365

Silicon Valley Bank

The Company entered into a Loan and Security Agreement dated April 18, 2018 (the “LSA”) with Silicon Valley Bank (“SVB”) as amended by a First Amendment to the Loan and Security (the “First Amendment”) dated February 14, 2019, a Second Amendment dated December 31, 2019 (the “Second Amendment”) and a Third Amendment dated August 3, 2020 (the “Third Amendment”). The LSA, as amended by the First Amendment, Second Amendment and Third Amendment (collectively the “SVB Credit Facility”) matures August 3, 2024.

The Company borrowed $10.0 million (the "Tranche 1") upon execution of the First Amendment and $10.0 million (the "Tranche 2") upon execution of the Second Amendment and repaid the term loans in August 2020 using the proceeds received from the CRG Term Loan Facility (described below). The term loans accrued interest, payable monthly in arrears, at a floating per annum rate equal to the greater of (i) prime rate plus 2.25% as published in the money rates section of the Wall Street Journal, or (ii) seven and one-half percent (7.5%) for Tranche 1 and Tranche 2.

Under the Third Amendment, the SVB Credit Facility provides for up to $10.0 million in a revolving line of credit. Availability under the revolving line of credit is subject to a formula based on, among other things, eligible accounts receivable. Borrowings on the line of credit bear interest at a floating rate per annum equal to the greater of (a) 1.00% above the prime rate as published from time to time in the money rates section of the Wall Street Journal and (b) 5.00%, and includes a termination fee of 1.00% of the revolving line of credit if the termination occurs before August 3, 2022.

Under the terms of the SVB Credit Facility, the Company granted SVB first priority liens and security interests in substantially all of the Company’s assets (excluding its intellectual property but including any proceeds and rights to payments associated with our intellectual property) as collateral. The SVB Credit Facility also contains certain representations and warranties, indemnification provisions in favor of SVB, affirmative and negative covenants (including, among other things, requirements that the Company maintain a minimum amount of liquidity and achieve minimum revenue targets, limitations on other indebtedness, liens, acquisitions, investments and dividends and requirements relating to financial reporting, sales and leasebacks, insurance and protection of the Company’s intellectual property rights) and events of default (including payment defaults, breaches of covenants following any applicable cure period, investor abandonment, a material impairment in the perfection or priority of the lender’s security interest or in the collateral, and events relating to bankruptcy or insolvency).

The Company issued warrants in connection with the SVB Credit Facility that gave the lender the right to purchase up to 713,330 shares of the Company’s Class A common stock (refer to Note 9, "Warrants for Class A Common Stock").

The Company paid issuance costs in connection with the SVB Credit Facility of $0.3 million which were recorded as a reduction of debt. The debt discount and debt issuance costs were amortized over the term of the debt using the effective interest method and included within interest expense on the statements of operations and comprehensive loss. Upon repayment of the term loans under the SVB Credit Facility in August 2020, the Company recognized a loss of $0.6 million for the year ended December 31, 2020 within interest and other income (expense), net, relating to unamortized balance of debt issuance costs and debt discount.

The Company did not have any balances outstanding under the revolving line of credit as of December 31, 2021 and 2020. As of December 31, 2021, the Company had $10.0 million in available borrowings on the line of credit and was in compliance with all covenants under the SVB Credit Facility.

CRG Term Loan Facility

On July 31, 2020, the Company entered into the CRG Term Loan Facility, to obtain up to $50.0 million in financing over three tranches to be advanced no later than December 31, 2021. Principal amounts totaling $30.0 million were borrowed through December 31, 2021 and are currently outstanding. The CRG Term Loan Facility matures on June 30, 2025, and the Company could elect to make quarterly interest-only payments or to pay interest in-kind through December 31, 2020. The Company is not required to make any principal payments until the maturity of the CRG Term Loan Facility and all outstanding principal and accrued interest are due upon the maturity of the CRG Term Loan Facility. Interest under the CRG Term Loan Facility is applied to outstanding principal and accrued interest at a rate of 13.00% per annum. If an event of default occurs, interest under the CRG Term Loan Facility will increase by 4.00%. If the Company repaid the CRG Term Loan Facility within one year of the borrowing date, the Company was required to pay a premium of 20.00% of the aggregated outstanding principal amount of the loans that was repaid. If the Company repays the CRG Term Loan Facility between one and two years from the borrowing date, it is required to pay a premium of 11.00% of the aggregated outstanding principal amount of the loans that is repaid. The CRG Term Loan Facility does not require a prepayment premium for loans being prepaid on the prepayment date that is longer than two years from the initial borrowing date.

Under the terms of the CRG Term Loan Facility, the Company granted first priority liens and security interests in substantially all of the Company’s assets as collateral (including the Company’s intellectual property), provided that the priority of such liens is

subject to an intercreditor agreement between CRG and SVB. The CRG Term Loan Facility also contains certain representations and warranties, indemnification provisions in favor of CRG, affirmative and negative covenants (including, among other things, requirements that the Company maintain a minimum amount of liquidity and achieve minimum revenue targets, comply with limitations on other indebtedness, liens, acquisitions, investments and dividends and requirements relating to financial reporting, sales and leasebacks, insurance and protection of the Company’s intellectual property rights) and events of default (including payment defaults, breaches of covenants following any applicable cure period, investor abandonment, a material impairment in the perfection or priority of the lender’s security interest or in the collateral, and events relating to bankruptcy or insolvency).

The Company paid $0.5 million in fees to CRG and $0.2 million in fees to third parties in connection with the CRG Term Loan Facility. The fees were recorded as debt issuance costs and classified as contra-debt. In addition, the Company recognized $0.2 million as debt discount on borrowings under the CRG Term Loan Facility due to embedded features contained in the agreement which resulted in a derivative liability (Note 4). Debt issuance costs and debt discount are amortized to interest expense using the effective interest method.

As of December 31, 2021 and 2020, the balance outstanding under the CRG Term Loan Facility, net of debt issuance costs and debt discount, was $29.4 million and $29.2 million, respectively.

PPP Loan

The Company applied for and received a $1.8 million loan (the “PPP Loan”) under the Paycheck Protection Program (the “PPP”) under the Coronavirus Aid Relief, and Economic Security Act (“CARES Act”). The PPP Loan, which was in the form of a promissory note, dated April 22, 2020, between the Company and SVB as the lender, was scheduled to mature on April 22, 2022, accrued interest at a fixed rate of 1% per annum, and was payable monthly. The Company repaid $1.8 million borrowed under the PPP Loan in March 2021.

During the years ended December 31, 2021, 2020, and 2019, the Company recorded, $4.1 million, $2.7 million and $0.8 million, respectively, in interest expense related to the borrowings under the SVB Credit Facility and CRG Credit Facility. During the years ended December 31, 2021 and 2020, amortization of the debt discount was $0.2 million and $0.1 million, respectively. During the year ended December 31, 2019 amortization of the debt discount was immaterial.

Income Taxes

12 Months Ended

Dec. 31, 2021

Income Tax Disclosure [Abstract]

Income Taxes

8. Income Taxes

The Company has not recorded an income tax provision for years ended December 31, 2021, 2020 and 2019 due to its operating losses. All losses before income taxes were generated in the United States.

Reconciliation of the statutory federal income tax to the Company’s effective tax is as follows:


	December 31,
	2021			2020			2019
Income tax at the statutory rate		(21	)%		(21	)%		(21	)%
Stock-based and other compensation		(8	)%		0	%		0	%
State taxes, net of federal benefit		(6	)%		(4	)%		(4	)%
Research and development credits		(1	)%		(4	)%		(3	)%
Change in valuation allowance		32	%		28	%		27	%
Other		4	%		1	%		1	%
Effective tax rate		0	%		0	%		0	%

The tax effects of temporary differences and carryforwards that give rise to significant portions of deferred tax assets were as follows (in thousands):


	December 31,
	2021			2020
Components of the deferred tax assets
Net operating loss carryforwards	$	8,264		$	3,703
Interest expense		1,025			—
Stock option compensation expense		456			672
Accrued bonus		726			244
Research and development credits		717			475
Other		753			407
Total deferred tax assets		11,941			5,501
Deferred tax asset valuation allowance		(11,941	)		(5,501	)
Net deferred tax assets	$	—		$	—

In assessing the realizability of deferred tax assets, management considers whether it is more likely than not that some portion or all of the deferred tax asset will not be realized. The ultimate realization of deferred tax assets is dependent upon the generation of future taxable income during the periods in which those temporary differences become deductible. Management considers the scheduled reversal of deferred tax assets, projected future taxable income, and tax planning strategies in making this assessment. Due to the Company’s history of net losses, the deferred tax assets have been fully offset by full valuation allowance of $11.9 million and $5.5 million as of December 31, 2021 and December 31, 2020, respectively. The Company’s change in the deferred tax asset valuation allowance for the years ended December 31, 2021 and 2020, were approximately $6.4 million and $0.9 million, respectively.

The Company had unused federal and state net operating loss carryforwards of approximately $35.4 million and $17.2 million, respectively as of December 31, 2021, and federal and state net operating loss carryforwards of approximately $14.6 million and $9.5 million, respectively, as of December 31, 2020. The net operating loss carryforwards begin to expire in 2034. The Company's research and development tax credit carryforwards were $0.7 million and $0.4 million as of December 31, 2021 and 2020, respectively, and begin to expire in 2037.

The federal and state net operating loss carryforwards and credits may be subject to significant limitations under Section 382 and Section 383 of the Internal Revenue Code and similar provisions under state law. The Tax Reform Act contains provisions that limit the federal net operating loss carryforwards that may be used in any given year in the event of special occurrences, including significant ownership changes. A Section 382 “ownership change” generally occurs if one or more stockholders or groups of stockholders, who own at least 5% of the Company’s stock, increase their ownership by more than 50 percentage points over their lowest ownership percentage within a rolling three-year period. The Company may have previously experienced, and may in the future experience, one or more Section 382 “ownership changes,” including in connection with the Company’s initial public offering. If so, the Company may lose some or all of the tax benefits of its carryforwards and credits.

Management has reviewed and evaluated the relevant technical merits of each of its tax positions in accordance with accounting principles generally accepted in the United States of America for accounting for uncertainty in income taxes and determined that there are no uncertain tax positions that would have a material impact on the financial statements of the Company. The Company is not subject to U.S. Federal and state income tax examinations by tax authorities for tax years before 2017.

- Definition

The entire disclosure for income taxes. Disclosures may include net deferred tax liability or asset recognized in an enterprise's statement of financial position, net change during the year in the total valuation allowance, approximate tax effect of each type of temporary difference and carryforward that gives rise to a significant portion of deferred tax liabilities and deferred tax assets, utilization of a tax carryback, and tax uncertainties information.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
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+ Details

Stockholders' Equity

12 Months Ended

Dec. 31, 2021

Stockholders Equity Note [Abstract]

Stockholders' Equity

10. Stockholders’ Equity

Series A Convertible Preferred Stock

Immediately before the completion of the IPO, all outstanding shares of Series A convertible preferred stock were converted into shares of the Company’s common stock. Accordingly, no shares of Series A convertible preferred stock were outstanding as of December 31, 2021.

Upon the closing of the IPO in April 2021, the Company issued 158,447 shares of common stock, to settle accrued and unpaid Series A convertible preferred stock dividends of $2.5 million. At December 31, 2020, the Company had accrued and unpaid dividends of $2.3 million on the Series A convertible preferred stock outstanding.

Preferred Stock

Upon the closing of the IPO, the Company is authorized to issue 5,000,000 shares of preferred stock. As of December 31, 2021, no shares of preferred stock were outstanding.

Common Stock

On April 27, 2021, the Company amended and restated its Certificate of Incorporation, which became effective upon the closing of the IPO. The Company is authorized to issue 300,000,000 shares of common stock.

Shares Reserved for Future Issuance

The Company has reserved shares of common stock for future issuances as follows:


	December 31,
	2021		2020
Series A convertible preferred stock outstanding		—		6,687,475
Warrants to purchase Class A common stock		—		713,330
Estimated preferred share conversion for dividends in kind		—		334,316
Common stock options issued and outstanding		7,464,580		8,081,828
Shares available for future awards granted under the 2021 Plan		3,766,337		—
Unvested restricted stock units under the 2021 Plan		10,000		—
Common stock available for Employee Stock Purchase Plan		504,627		—
Class A common stock available for future grants		—		13,691,186
Class B common stock available for future grants		—		1,000,000
Total		11,745,544		30,508,135

Stock Option Plans

In April 2021, prior to the IPO closing, the Company’s Board of Directors and stockholders approved the 2021 Incentive Award Plan (“2021 Plan”), which became effective upon the IPO closing. The Company has initially reserved 5,046,278 shares of common stock for issuance share-based compensation awards, including stock options, restricted stock awards, restricted stock unit awards and other stock-based awards. The number of shares initially reserved for issuance or transfer pursuant to awards under the 2021 Plan will be increased by (i) the number of shares represented by awards outstanding under the Company’s 2014 Stock Option Plan (“2014 Plan”) that become available for issuance under the terms of the 2021 Plan and (ii) an annual increase on the first day of each fiscal year beginning in 2022 and ending in 2031, equal to the lesser of (i) 5.0% of the shares of stock outstanding (on an as converted basis) on the last day of the immediately preceding fiscal year and (ii) such smaller number of shares of stock as determined by our board of directors; provided, however, that no more than 37,847,090 shares of stock may be issued upon the exercise of incentive stock options.

Prior to the IPO, the Company was authorized to issue stock purchase rights and to grant options to purchase Class A Common Stock to employees, directors and consultants under the 2014 Plan. Stock options under the 2014 Plan have a term of no more than ten years from the date of grant and vest in equal installments over a maximum of five years. No future awards can be granted under the 2014 Plan. The shares underlying outstanding and unexercised options granted to employees, directors and consultants under the 2014 Plan may become available for issuance under the 2021 Plan as follows: (i) to the extent that such an option award terminates, expires or lapses for any reason or is settled in cash without the delivery of shares, any shares subject to the award at such time will be available for future grants under the 2021 Plan; (ii) to the extent shares are tendered or withheld to satisfy the grant, exercise price or tax withholding obligation with respect to any award under the 2014 Plan, such tendered or withheld shares will be available for future grants under the 2021 Plan; and (iii) to the extent that the Company repurchases the shares prior to vesting so that shares are returned to the Company, such shares will be available for future grants under the 2021 Plan.

Options under the 2021 Plan may be granted for periods of up to 10 years at exercise prices no less than the fair market value of our common stock on the date of grant; provided, however, that the exercise price of an incentive stock option granted to a 10% stockholder may not be less than 110% of the fair market value of the shares on the date of grant and such option may not be exercisable after the expiration of five years from the date of grant. Options usually vest ratably annually over 4 years.

At December 31, 2021, 3,766,337 shares of common stock remain available for issuance as awards under the 2021 Plan. In January 2022, the number of shares of common stock available for issuance under the 2021 Plan was increased by 2,709,054 shares as a result of the automatic increase provision in the 2021 Plan.

Activity under the Stock Plans is set forth below:


	Outstanding Options
	Number of Shares			Weighted- Average Remaining Contractual Term (in Years)		Weighted- Average Exercise Price
Balance, December 31, 2020		8,081,828			6.86	$	1.82
Options granted		2,106,247				$	17.49
Options exercised		(2,368,705	)			$	0.79
Options canceled		(354,790	)			$	6.17
Balance, December 31, 2021		7,464,580			6.89	$	6.36
Options vested and expected to vest at December 31, 2021		6,281,149			6.48	$	5.01
Options vested and exercisable at December 31, 2021		3,727,642			5.13	$	1.76

The aggregate intrinsic value of options exercised during the years ended December 31, 2021, 2020 and 2019 was $39.1 million, $1.9 million and $0.9 million, respectively. The aggregate intrinsic value is calculated as the difference between the exercise price of the underlying stock options and the fair value of the Company’s common stock for stock options that were in-the-money as of year-end. Aggregate intrinsic values of options outstanding, options vested and expected to vest and options exercisable were $97.2 million, $88.7 million and $62.9 million as of December 31, 2021, respectively.

Restricted Stock Awards

During the year ended December 31, 2021 the Company granted 24,895 restricted stock awards (“RSA”) and 10,000 restricted stock units ("RSU"). RSAs and RSUs vests annually over 4 years in equal installments. The Company had 19,024 RSAs and 10,000 RSUs unvested as of December 31, 2021. The weighted average grant-date fair value per share of unvested RSAs and RSUs as of December 31, 2021 was $31.5 and $22.1, respectively. The Company did not grant RSAs and RSUs during the years ended December 31, 2020 and 2019, and had no unvested RSAs and RSUs as of December 31, 2020 and 2019.

Employee Share Purchase Plan

In April 2021, the Company’s Board of Directors and stockholders approved the 2021 Employee Stock Purchase Plan (“ESPP”). The Company has initially reserved 504,627 shares of common stock for purchase under the ESPP. The number of shares of common stock reserved for issuance under the 2021 ESPP will be automatically increased each year for ten calendar years beginning in 2022 by the number of shares equal to the lesser of 1% of the total number of shares of common stock outstanding as of the last day of the immediately preceding fiscal year or such number of shares as may be determined by the Board of Directors of the Company; provided that the maximum number of shares that may be issued under the ESPP is 7,064,790 shares. Each offering to the employees to purchase stock under the ESPP will begin on a date to be determined by the Company’s Compensation Committee and will end no later than six months thereafter. The ESPP allows an eligible employee to purchase shares of our common stock at a discount through payroll deductions of up to 15% of the employee’s eligible compensation. At the end of each offering period, employees are able to purchase shares at 85% of the lower of the fair market value of our common stock at the beginning of the offering period or at the end of each applicable offering period. The occurrence and duration of offering periods under the ESPP are subject to the determinations of the Company’s Compensation Committee, in its sole discretion. The Company has not yet commenced any enrollment periods under the ESPP.

In January 2022, the number of shares of common stock available for issuance under the ESPP was increased to 541,810 shares as a result of the automatic increase provision in the ESPP.

Stock-Based Compensation

The weighted-average grant date fair values of the stock options granted were $6.19, $2.26 and $0.93 per share for the years ended December 31, 2021, 2020 and 2019, respectively.

The Company uses the Black-Scholes option pricing model to determine the fair value of stock options at the grant dates with the following assumptions for options granted during 2021, 2020 and 2019 fiscal years:


	December 31,
	2021	2020	2019
Expected term (in years)	2.1-6.25	2.7 - 3.3	3
Expected volatility	35.57% - 55.60%	37.09% - 51.29%	49.19%
Risk-free interest rate	0.08% - 1.39%	0.18% - 1.53%	2.30%
Expected dividend yield	0.00%	0.00%	0.00%

Stock-based compensation expense is reflected in the statements of operations and comprehensive loss as follows (in thousands):


	Years Ended December 31,
	2021		2020		2019
Sales and marketing expense	$	1,231	$	479	$	405
Research and development expense		475		199		160
General and administrative expense		1,703		241		250
Total	$	3,409	$	919	$	815

As of December 31, 2021, there was $12.1 million of unrecognized stock-based compensation expense related to common stock options, which the Company expects to recognize over a weighted-average period of 3.2 years. As of December 31, 2021, there was $0.6 million of unrecognized stock-based compensation expense related to RSAs and RSUs, which the Company expects to recognize over a weighted-average period of 2.73 years.

The total grant date fair value of shares vested during the years ended December 31, 2021, 2020 and 2019 were $2.0 million, $0.9 million and $0.8 million, respectively.

- Definition

The entire disclosure for shareholders' equity comprised of portions attributable to the parent entity and noncontrolling interest, including other comprehensive income. Includes, but is not limited to, balances of common stock, preferred stock, additional paid-in capital, other capital and retained earnings, accumulated balance for each classification of other comprehensive income and amount of comprehensive income.

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+ Details

Net Loss Per Share Attributable to Common Stockholders

12 Months Ended

Dec. 31, 2021

Earnings Per Share [Abstract]

Net Loss Per Share Attributable to Common Stockholders

12. Net Loss Per Share Attributable to Common Stockholders

The following table sets forth the computation of basic and diluted net loss per share attributable to common stockholders which is computed by dividing the net loss attributable to common stockholders by the weighted- average number of shares of common stock outstanding for the period. As the Company reported a net loss for the years ended December 31, 2021, 2020 and 2019, respectively, basic net loss per share attributable to common stockholders was the same as diluted net loss per share attributable to common stockholders as the inclusion of potentially dilutive shares would have been antidilutive if included in the calculation (in thousands, except share and per share amounts):


	Years Ended December 31,
	2021			2020			2019
Numerator
Net loss	$	(20,552	)	$	(3,668	)	$	(4,265	)
Adjust: Convertible preferred stock cumulative and undeclared dividends		(196	)		(640	)		(640	)
Net loss attributable to common stockholders		(20,748	)		(4,308	)		(4,905	)
Denominator
Weighted-average common stock outstanding, basic and diluted		48,415,679			37,068,965			36,911,586
Net loss per share attributable to common stockholders, basic and diluted	$	(0.43	)	$	(0.12	)	$	(0.13	)

The following potentially dilutive securities outstanding have been excluded from the computation of diluted weighted average shares outstanding because such securities have an antidilutive impact due to the Company’s net loss, in common stock equivalent shares:


	December 31,
	2021		2020		2019
Series A convertible preferred stock outstanding		—		6,687,475		6,687,475
Warrants to purchase Class A common stock		—		713,330		713,330
Common stock options issued and outstanding		7,464,580		8,081,828		7,474,401
Unvested restricted stock awards and restricted stock units		29,024		—		—
Total		7,464,580		15,482,633		14,875,206

Summary of Significant Accounting Policies (Policies)

12 Months Ended

Dec. 31, 2021

Accounting Policies [Abstract]

Basis of Presentation

Use of Estimates

Fair Value of Financial Instruments

Segments

Cash and Cash Equivalents

The Company considers all highly liquid investments with an original or remaining maturity of three months or less at the time of purchase to be cash equivalents, which include money market funds.

Accounts Receivable and Allowances

Concentration of Credit Risk

Inventories

Property and Equipment, Net

Property and equipment is recorded at cost. Depreciation of property and equipment is recorded using the straight-line method over the following estimated useful lives as follows:


		Years
Furniture, fixtures and equipment		7
Machinery and equipment		3
Capitalized surgical instruments		3
Computer equipment		3
Leasehold improvements		5 or lease term, whichever is shorter
Software		3

Leases

Revenue Recognition

implant kits and ancillary products and pays commissions to the sales representatives and independent sales agencies. The Company has no international sales.

(i)

identify the contract(s) with a customer;

(ii)

identify the performance obligations in the contract;

(iii)

determine the transaction price;

(iv)

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

(v)

recognize revenue when (or as) the entity satisfies performance obligations.

Contract Costs

Cost of Goods Sold

Research and Development Expenses

Shipping and Handling

Advertising Costs

Income Taxes

Product Liability

Stock-Based Compensation

The Company estimates the fair value of the stock-based awards using the Black-Scholes option-pricing model, which requires the input of highly subjective assumptions. The assumptions are as follows:

•

Expected Dividend Yield. The expected dividend yield is zero as the Company has not paid nor anticipates paying any dividends on the common stock in the foreseeable future.

•

Comprehensive Loss

Net Loss Per Share Attributable to Common Stockholders

Derivative Liability

Deferred Issuance Costs

Fair Value Measurements (Tables)

12 Months Ended

Dec. 31, 2021

Fair Value Disclosures [Abstract]

Summary of Assets and Liabilities Measured at Fair Value on Recurring Basis


	December 31, 2021
	Level 1		Level 2		Level 3		Total
Assets:
Money market funds(1)	$	105,220	$	—	$	—	$	105,220
Total	$	105,220	$	—	$	—	$	105,220
Liabilities:
Derivative liability	$	—	$	—	$	173	$	173
Total	$	—	$	—	$	173	$	173


	December 31, 2020
	Level 1		Level 2		Level 3		Total
Assets:
Money market funds(1)	$	17,577	$	—	$	—	$	17,577
Total	$	17,577	$	—	$	—	$	17,577
Liabilities:
Derivative liability	$	—	$	—	$	245	$	245
Total	$	—	$	—	$	245	$	245

(1)

Money market funds are included in cash and cash equivalents in the balance sheets as of December 31, 2021 and 2020.

Summary of the Changes in the Fair Value of the Company's Financial Instruments

The following table sets forth a summary of the changes in the fair value of the Company’s Level 3 financial instruments (in thousands):


	Derivative liability
Fair value as of January 1, 2020	$	—
Initial fair value of derivative liability		245
Fair value as of December 31, 2020		245
Change in fair value included in other expense, net		(72	)
Fair value as of December 31, 2021	$	173

Balance Sheet Components (Tables)

12 Months Ended

Dec. 31, 2021

Balance Sheet Related Disclosures [Abstract]

Summary of Cash and Cash Equivalents

The Company’s cash and cash equivalents consisted of the following (in thousands):


	December 31,
	2021		2020
Cash	$	613	$	502
Cash equivalents:
Money market funds		105,220		17,577
Total cash and cash equivalents	$	105,833	$	18,079

Summary of Property and Equipment, Net

The company’s property and equipment, net consisted of the following (in thousands):


	December 31,
	2021			2020
Furniture and fixtures, and equipment	$	180		$	131
Construction in progress		126			—
Machinery and equipment		274			226
Capitalized surgical equipment		4,442			2,652
Computer equipment		160			150
Leasehold improvements		268			168
Software		138			138
Total property and equipment		5,588			3,465
Less: accumulated depreciation and amortization		(2,739	)		(2,636	)
Property and equipment, net	$	2,849		$	829

Summary of Accrued Liabilities

Accrued liabilities consist of the following (in thousands):


	December 31,
	2021		2020
Accrued royalties expense	$	1,522	$	1,032
Accrued interest		975		—
Accrued professional services		941		375
Other accrued expense		1,080		441
Total accrued liabilities	$	4,518	$	1,848

Long Term Debt (Tables)

12 Months Ended

Dec. 31, 2021

Debt Disclosure [Abstract]

Summary of Long-term Debt Instruments

The Company’s debt consisted of the following (in thousands):


	December 31,
	2021			2020
Revolving line of credit
SVB Credit Facility	$	—		$	—
Term loans
CRG Term Loan Facility		30,000			30,000
PPP Loan		—			1,788
Total term loans		30,000			31,788
Less: debt discount and issuance costs		(635	)		(811	)
Total debt		29,365			30,977
Short-term debt		—			1,788
Long-term debt	$	29,365		$	29,189

Summary of Maturities of Long-term Debt

As of December 31, 2021, future payments under term loan were as follows (in thousands):


Fiscal Year
2022	$	—
2023		—
2024		—
2025		30,000
Total principal payments		30,000
Less: Unamortized debt discount and debt issuance costs		(635	)
Total short-term and long-term debt	$	29,365

- Definition

Tabular disclosure of long-debt instruments or arrangements, including identification, terms, features, collateral requirements and other information necessary to a fair presentation. These are debt arrangements that originally required repayment more than twelve months after issuance or greater than the normal operating cycle of the entity, if longer.

+ References

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+ Details

Income Taxes (Tables)

12 Months Ended

Dec. 31, 2021

Income Tax Disclosure [Abstract]

Summary of Reconciliation of Statutory Federal Income Tax to Effective Tax

Reconciliation of the statutory federal income tax to the Company’s effective tax is as follows:


	December 31,
	2021			2020			2019
Income tax at the statutory rate		(21	)%		(21	)%		(21	)%
Stock-based and other compensation		(8	)%		0	%		0	%
State taxes, net of federal benefit		(6	)%		(4	)%		(4	)%
Research and development credits		(1	)%		(4	)%		(3	)%
Change in valuation allowance		32	%		28	%		27	%
Other		4	%		1	%		1	%
Effective tax rate		0	%		0	%		0	%

Summary of Tax Effects of Temporary Differences and Carryforwards to Significant Portions of Deferred Tax Assets

The tax effects of temporary differences and carryforwards that give rise to significant portions of deferred tax assets were as follows (in thousands):


	December 31,
	2021			2020
Components of the deferred tax assets
Net operating loss carryforwards	$	8,264		$	3,703
Interest expense		1,025			—
Stock option compensation expense		456			672
Accrued bonus		726			244
Research and development credits		717			475
Other		753			407
Total deferred tax assets		11,941			5,501
Deferred tax asset valuation allowance		(11,941	)		(5,501	)
Net deferred tax assets	$	—		$	—

Stockholders' Equity (Tables)

12 Months Ended

Dec. 31, 2021

Stockholders Equity Note [Abstract]

Summary of the Company has Reserved Shares of Common Stock for Future Issuances

The Company has reserved shares of common stock for future issuances as follows:


	December 31,
	2021		2020
Series A convertible preferred stock outstanding		—		6,687,475
Warrants to purchase Class A common stock		—		713,330
Estimated preferred share conversion for dividends in kind		—		334,316
Common stock options issued and outstanding		7,464,580		8,081,828
Shares available for future awards granted under the 2021 Plan		3,766,337		—
Unvested restricted stock units under the 2021 Plan		10,000		—
Common stock available for Employee Stock Purchase Plan		504,627		—
Class A common stock available for future grants		—		13,691,186
Class B common stock available for future grants		—		1,000,000
Total		11,745,544		30,508,135

Summary of Activity under Stock Plans

Activity under the Stock Plans is set forth below:


	Outstanding Options
	Number of Shares			Weighted- Average Remaining Contractual Term (in Years)		Weighted- Average Exercise Price
Balance, December 31, 2020		8,081,828			6.86	$	1.82
Options granted		2,106,247				$	17.49
Options exercised		(2,368,705	)			$	0.79
Options canceled		(354,790	)			$	6.17
Balance, December 31, 2021		7,464,580			6.89	$	6.36
Options vested and expected to vest at December 31, 2021		6,281,149			6.48	$	5.01
Options vested and exercisable at December 31, 2021		3,727,642			5.13	$	1.76

Summary of Company Determined the Fair Value of Warrants using Black-Scholes Option Pricing Model


	December 31,
	2021	2020	2019
Expected term (in years)	2.1-6.25	2.7 - 3.3	3
Expected volatility	35.57% - 55.60%	37.09% - 51.29%	49.19%
Risk-free interest rate	0.08% - 1.39%	0.18% - 1.53%	2.30%
Expected dividend yield	0.00%	0.00%	0.00%

Summary of Share-Based Compensation Expense is Reflected in the Statements of Operations and Comprehensive Loss

Stock-based compensation expense is reflected in the statements of operations and comprehensive loss as follows (in thousands):


	Years Ended December 31,
	2021		2020		2019
Sales and marketing expense	$	1,231	$	479	$	405
Research and development expense		475		199		160
General and administrative expense		1,703		241		250
Total	$	3,409	$	919	$	815

Net Loss Per Share Attributable to Common Stockholders (Tables)

12 Months Ended

Dec. 31, 2021

Earnings Per Share [Abstract]

Schedule of Net Loss Per Share Attributable to Common Stockholders, Basic and Diluted

As the Company reported a net loss for the years ended December 31, 2021, 2020 and 2019, respectively, basic net loss per share attributable to common stockholders was the same as diluted net loss per share attributable to common stockholders as the inclusion of potentially dilutive shares would have been antidilutive if included in the calculation (in thousands, except share and per share amounts):


	Years Ended December 31,
	2021			2020			2019
Numerator
Net loss	$	(20,552	)	$	(3,668	)	$	(4,265	)
Adjust: Convertible preferred stock cumulative and undeclared dividends		(196	)		(640	)		(640	)
Net loss attributable to common stockholders		(20,748	)		(4,308	)		(4,905	)
Denominator
Weighted-average common stock outstanding, basic and diluted		48,415,679			37,068,965			36,911,586
Net loss per share attributable to common stockholders, basic and diluted	$	(0.43	)	$	(0.12	)	$	(0.13	)

Summary of Potentially Dilutive Securities Excluded from Computation of Diluted Weighted Average Shares Outstanding


	December 31,
	2021		2020		2019
Series A convertible preferred stock outstanding		—		6,687,475		6,687,475
Warrants to purchase Class A common stock		—		713,330		713,330
Common stock options issued and outstanding		7,464,580		8,081,828		7,474,401
Unvested restricted stock awards and restricted stock units		29,024		—		—
Total		7,464,580		15,482,633		14,875,206

Formation and Business of the Company - Additional Information (Detail)			12 Months Ended
	Apr. 27, 2021 USD ($) $ / shares shares	Apr. 16, 2021 $ / shares shares	Dec. 31, 2021 USD ($) $ / shares shares	Dec. 31, 2020 USD ($) $ / shares shares	Dec. 31, 2019 USD ($)	Dec. 31, 2018 USD ($)
Formation And Business Of The Company [Line Items]
Stock issued during the period shares including sale by the existing shareholders	12,937,500
Sale of stock issue price per share \| $ / shares	$ 17.00
Underwriting discounts and commissions \| $	$ 8,300,000
Adjustment to additional paid in capital stock issuance costs \| $	$ 2,300,000
Preferred stock shares outstanding converted into equity shares	6,687,475
Stock split ratio		1.3375
Common stock shares authorized	300,000,000
Preferred stock shares authorized	5,000,000
Common stock, par or stated value per share \| $ / shares		$ 0.001
Preferred stock, par or stated value per share \| $ / shares		$ 0.001
Accumulated deficit \| $			$ (41,905,000)	$ (21,353,000)
Net cash used in operating activities \| $			(17,193,000)	(4,494,000)	$ (7,673,000)
Cash and cash equivalents \| $			105,833,000	$ 18,079,000	$ 12,139,000	$ 1,284,000
Forward Stock Split [Member]
Formation And Business Of The Company [Line Items]
Shares authorized preferred and common stock		73,562,500
Common stock shares authorized		66,875,000
Preferred stock shares authorized		6,687,500
IPO [Member]
Formation And Business Of The Company [Line Items]
Stock issued during the period shares new issues	6,953,125
Sale of stock by the existing shareholders	5,984,375
Sale of stock net consideration received on the transaction \| $	$ 107,600,000
Over-Allotment Option [Member]
Formation And Business Of The Company [Line Items]
Stock issued during the period shares new issues	703,125
Sale of stock by the existing shareholders	984,375
Selling Stockholders [Member]
Formation And Business Of The Company [Line Items]
Proceeds from sale of shares \| $			$ 0
Series A Convertible Preferred Stock [Member]
Formation And Business Of The Company [Line Items]
Stock shares issued during the period shares dividends	158,447
Stock shares issued during the period value dividends \| $	$ 2,500,000
Preferred stock shares authorized			0	6,687,500
Preferred stock, par or stated value per share \| $ / shares			$ 0.001	$ 0.001

Summary of Significant Accounting Policies -Additional Information (Detail)	12 Months Ended
	Dec. 31, 2021 USD ($) Segment	Dec. 31, 2020 USD ($)	Dec. 31, 2019 USD ($)
Summary Of Significant Accounting Policies [Line Items]
Accrued contingent liabilities	$ 0	$ 0
Number of reportable segment \| Segment	1
Number of operating segment \| Segment	1
Net of an allowance for doubtful accounts	$ 400,000	400,000
Provision for bad debts	144,000	216,000	$ 145,000
Provision for inventory obsolescence	347,000	1,144,000
Revenue recognition international sales	$ 0
Revenue recognition shipments to customers right to return description	shipments to customers, the Company offers the right to return the product within 30 days for a full refund, and for returns between 30 and 90 days, the Company offers a full refund less 15% restocking fee. The Company does not have a history of product returns for refund. Customer invoices are generally payable within 30 days. The Company’s products are generally sold with a limited standard warranty to the original purchaser of the products against defects in workmanship and materials for 180 days. The Company’s liability is limited to providing, at the Company’s option, a full refund or credit of the purchase price, or repairing or replacing the product, provided that the customer returns the defective product within 180 days from the purchase date. To date, the Company has had negligible returns of any products alleged to be defective.
Contract with customer, refund liability	$ 0	0
Contract with customer, product returns	$ 0	0	0
Practical expedient, incremental cost of obtaining contract	true
Advertising costs	$ 13,020,000.00	3,100,000	$ 1,900,000
Liability related to uncertain tax positions	0
Accruals for product liability	$ 0	$ 0
Expected dividend yield	0.00%	0.00%	0.00%
Capitalized issuance costs	$ 0	$ 200,000
Capitalized Surgical Instruments [Member]
Summary Of Significant Accounting Policies [Line Items]
Useful life of its capitalized instruments	3 years
Decrease in depreciation expense	$ 300,000
ASC 606 [Member]
Summary Of Significant Accounting Policies [Line Items]
Change in accounting principle, accounting standards update, adoption date	Jan. 01, 2019
Change in accounting principle, accounting standards update, adopted	true
Change in accounting principle, accounting standards update, immaterial effect	true
Property and Equipment, Net [Member]
Summary Of Significant Accounting Policies [Line Items]
Property and equipment, net impairment charges	$ 0	100,000	$ 0
Obsolescence [Member]
Summary Of Significant Accounting Policies [Line Items]
Provision for inventory obsolescence	$ 300,000	$ 1,100,000	$ 100,000
Maximum [Member] \| Capitalized Surgical Instruments [Member]
Summary Of Significant Accounting Policies [Line Items]
Useful life of its capitalized instruments	36 months
Maximum [Member] \| Accounts Receivable [Member] \| Customer Concentration Risk [Member]
Summary Of Significant Accounting Policies [Line Items]
Concentration risk, percentage	10.00%	10.00%
Minimum [Member] \| Capitalized Surgical Instruments [Member]
Summary Of Significant Accounting Policies [Line Items]
Useful life of its capitalized instruments		18 months
Minimum [Member] \| Revenue Benchmark [Member] \| Customer Concentration Risk [Member]
Summary Of Significant Accounting Policies [Line Items]
Concentration risk, percentage	10.00%	10.00%	10.00%

Long Term Debt - Additional Information (Detail) - USD ($)						1 Months Ended	12 Months Ended
	Aug. 03, 2020	Jul. 31, 2020	Apr. 22, 2020	Feb. 14, 2019	Apr. 18, 2018	Mar. 31, 2021	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Debt Instrument [Line Items]
Class of warrants or rights number of shares issuable on conversion of warrants				713,330
Payment of debt issuance costs								$ 179,000	$ 329,000
Interest and other income (expense), net							$ 18,000	$ (1,746,000)	111,000
Long term debt fixed rate of interest								13.00%
Long term debt net of unamortized debt issuance costs and discount							29,365,000	$ 30,977,000
Amortization of debt discount							200,000	100,000
SVB Credit Facility And CRG Credit Facility [Member]
Debt Instrument [Line Items]
Interest expenses							4,100,000	2,700,000	$ 800,000
Revolving Credit Facility [Member]
Debt Instrument [Line Items]
Line of credit outstanding							0	0
CRG Term Loan Facility [Member]
Debt Instrument [Line Items]
Long-term Debt, Maturity Date		Jun. 30, 2025
Debt Instrument, Face Amount		$ 50,000,000.0
Proceeds from long term loan from the bank							30,000,000.0
Long term debt terms of interest payment		quarterly interest-only payments or to pay interest in-kind through December 31, 2020
Long term debt default rate of interest		4.00%
Debt discount gross								200,000
Long term debt net of unamortized debt issuance costs and discount							29,400,000	29,200,000
CRG Term Loan Facility [Member] \| Third Party [Member]
Debt Instrument [Line Items]
Debt issuance costs gross								500,000
CRG Term Loan Facility [Member] \| CRG [Member]
Debt Instrument [Line Items]
Debt issuance costs gross								$ 200,000
CRG Term Loan Facility [Member] \| Early Repayment Within One Year [Member]
Debt Instrument [Line Items]
Long term debt prepayment premium percentage								20.00%
CRG Term Loan Facility [Member] \| Early Repayment => 1Year But Within 2 Years [Member]
Debt Instrument [Line Items]
Long term debt prepayment premium percentage								11.00%
Long Term Loan Under Paycheck Protection Program [Member]
Debt Instrument [Line Items]
Long-term Debt, Maturity Date			Apr. 22, 2022
Proceeds from long term loan from the bank			$ 1,800,000
Long term debt fixed rate of interest			1.00%
Repayment of long term debt borrowed from the bank						$ 1,800,000
Loan and Security Agreement [Member]
Debt Instrument [Line Items]
Long-term Debt, Maturity Date					Aug. 03, 2024
Payment of debt issuance costs				$ 300,000
Interest and other income (expense), net								$ 600,000
Loan and Security Agreement [Member] \| Term Loans [Member] \| Tranche One And Two [Member]
Debt Instrument [Line Items]
Long term debt instrument variable interest rate percentage					7.50%
Loan and Security Agreement [Member] \| Term Loans [Member] \| Prime Rate [Member]
Debt Instrument [Line Items]
Debt instrument variable interest rate spread percentage					2.25%
First Amendment [Member] \| Term Loans [Member]
Debt Instrument [Line Items]
Borrowings					$ 10,000,000.0
Second Amendment [Member] \| Term Loans [Member]
Debt Instrument [Line Items]
Borrowings					$ 10,000,000.0
Third Amendment, SVB Credit Facility [Member]
Debt Instrument [Line Items]
Line of credit current borrowing capacity							$ 10,000,000.0
Third Amendment, SVB Credit Facility [Member] \| Revolving Credit Facility [Member]
Debt Instrument [Line Items]
Borrowings	$ 10,000,000.0
Debt instrument variable interest rate spread percentage	1.00%
Long term debt instrument variable interest rate percentage	5.00%
Debt instrument termination fee percentage	1.00%

Stockholders' Equity - Additional Information (Detail) - USD ($) $ / shares in Units, $ in Millions		1 Months Ended		12 Months Ended
	Apr. 27, 2021	Jan. 31, 2022	Apr. 30, 2021	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019	Apr. 21, 2021
Class Of Stock [Line Items]
Preferred shares outstanding				0
Preferred shares authorized	5,000,000
Common stock shares authorized	300,000,000
Shares of common stock reserved for issuance				11,745,544	30,508,135
Stock options, weighted-average grant date fair value				$ 6.19	$ 2.26	$ 0.93
Method used to determine the grant date fair value of warrants				Black-Scholes option pricing model		Black-Scholes option pricing model
Unvested unrecognized stock-based compensation expense				$ 12.1
Grant date fair value of shares vested				$ 2.0	$ 0.9	$ 0.8
IPO [Member]
Class Of Stock [Line Items]
Common stock, shares, issued	6,953,125
2021 Incentive Award Plan [Member]
Class Of Stock [Line Items]
Shares of common stock reserved for issuance				3,766,337			5,046,278
Percentage of shares of stock outstanding on an as converted basis							5.00%
Shares of stock may be issued upon the exercise							37,847,090
Percentage of incentive stock option granted to stockholder				10.00%
Stock option, Expiration period				5 years
Vesting period				4 years
2021 Incentive Award Plan [Member] \| Maximum [Member]
Class Of Stock [Line Items]
Stock options, Terms				10 years
Percentage of fair market value of stock options				110.00%
2021 Incentive Award Plan [Member] \| Subsequent Event [Member]
Class Of Stock [Line Items]
Number of common stock available for issuance increased		2,709,054
2014 Plan [Member]
Class Of Stock [Line Items]
Stock options, Terms				ten years
Vesting period				5 years
Stock Plan grant awards authorized				0
Aggregate intrinsic value of options exercised				$ 39.1	$ 1.9	$ 0.9
Aggregate intrinsic values of options outstanding				97.2
Aggregate intrinsic values of options vest and option exercisable				88.7
Aggregate intrinsic values of options exercisable				$ 62.9
Restricted Stock
Class Of Stock [Line Items]
Vesting period				4 years
Shares granted				24,895	0	0
Shares outstanding				19,024	0	0
Weighted average grant-date fair value				$ 31.5
Weighted-average period of recognition				2 years 8 months 23 days
Unvested unrecognized stock-based compensation expense, Other than options				$ 0.6
Restricted Stock Units [Member]
Class Of Stock [Line Items]
Vesting period				4 years
Shares granted				10,000	0	0
Shares outstanding				10,000	0	0
Weighted average grant-date fair value				$ 22.1
Weighted-average period of recognition				2 years 8 months 23 days
Unvested unrecognized stock-based compensation expense, Other than options				$ 0.6
Employee Share Purchase Plan [Member]
Class Of Stock [Line Items]
Shares of common stock reserved for issuance							504,627
Maximum subscription rate				15.00%
Common stock, Price per share percentage				85.00%
Employee Share Purchase Plan [Member] \| Maximum [Member]
Class Of Stock [Line Items]
Shares of common stock reserved for issuance							7,064,790
Employee Share Purchase Plan [Member] \| Subsequent Event [Member]
Class Of Stock [Line Items]
Number of common stock available for issuance increased		541,810
2021 ESPP [Member]
Class Of Stock [Line Items]
Increase in shares of common stock reserved for issuance period				10 years
2021 ESPP [Member] \| Maximum [Member]
Class Of Stock [Line Items]
Number of shares of common stock reserved increase percentage by annual of common stock outstanding				1.00%
Employee Stock Option [Member]
Class Of Stock [Line Items]
Shares of common stock reserved for issuance				7,464,580	8,081,828
Weighted-average period of recognition				3 years 2 months 12 days
Common Stock [Member]
Class Of Stock [Line Items]
Common stock, shares, issued				6,953,125
Common Stock [Member] \| IPO [Member]
Class Of Stock [Line Items]
Common stock, shares, issued			158,447
Series A Convertible Preferred Stock [Member]
Class Of Stock [Line Items]
Preferred shares outstanding				0	6,687,475
Preferred shares dividends unpaid				$ 2.5	$ 2.3
Preferred shares authorized				0	6,687,500

Stockholders' Equity - Summary of Activity under Stock Plans (Detail) - $ / shares	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Number of Shares Outstanding Options of Beginning Balance	8,081,828
Number of Shares Outstanding of Option Granted	2,106,247
Number of Shares Outstanding of Options Exercised	(2,368,705)
Number of Shares Outstanding of Options Canceled	(354,790)
Number of Shares Outstanding of Ending Balance	7,464,580	8,081,828
Number of Shares Options vested and expected to vest at December 31, 2021	6,281,149
Number of Shares Options vested and exercisable at December 31, 2021	3,727,642
Outstanding Options Weighted-Average Remaining Contractual Term	6 years 10 months 20 days	6 years 10 months 9 days
Options vested and expected to vest at December 31, 2021	6 years 5 months 23 days
Options vested and exercisable at December 31, 2021	5 years 1 month 17 days
Weighted-Average Exercise Price Beginning Balance	$ 1.82
Weighted-Average Exercise Price, Options granted	17.49
Weighted-Average Exercise Price, Options exercised	0.79
Weighted-Average Exercise Price, Options canceled	6.17
Weighted-Average Exercise Price, Ending Balance	6.36	$ 1.82
Weighted-Average Exercise Price, Options vested and expected to vest at December 31, 2021	5.01
Weighted-Average Exercise Price, Options vested and exercisable at December 31, 2021	$ 1.76

Net Loss Per Share Attributable to Common Stockholders - Schedule of Net Loss Per Share Attributable to Common Stockholders, Basic and Diluted (Detail) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Numerator
Net loss	$ (20,552)	$ (3,668)	$ (4,265)
Adjust: Convertible preferred stock cumulative and undeclared dividends	(196)	(640)	(640)
Net loss attributable to common stockholders	$ (20,748)	$ (4,308)	$ (4,905)
Denominator
Weighted-average common stock outstanding, basic and diluted	48,415,679	37,068,965	36,911,586
Net loss per share attributable to common stockholders, basic and diluted	$ (0.43)	$ (0.12)	$ (0.13)

- Definition

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

+ References

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- Definition

Amount, after deduction of tax, noncontrolling interests, dividends on preferred stock and participating securities; of income (loss) available to common shareholders.

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Statements of Stockholders' Equity (Parenthetical) $ in Millions	12 Months Ended
	Dec. 31, 2021 USD ($)
Statement Of Stockholders Equity [Abstract]
Issuance cost and underwriting discount	$ 10.6

Statements of Cash Flows (Parenthetical) $ in Millions	12 Months Ended
Statements of Cash Flows (Parenthetical) $ in Millions	Dec. 31, 2021 USD ($)
Statement Of Cash Flows [Abstract]
Issuance costs and underwriting fees, net	$ 10.6

Summary of Property and Equipment Depreciation Estimated Useful Lives (Detail)	12 Months Ended
	Dec. 31, 2021
Furniture Fixtures and Equipment [Member]
Property, Plant and Equipment [Line Items]
Property, plant and equipment, useful life	7 years
Machinery and Equipment [Member]
Property, Plant and Equipment [Line Items]
Property, plant and equipment, useful life	3 years
Capitalized Surgical Instruments [Member]
Property, Plant and Equipment [Line Items]
Property, plant and equipment, useful life	3 years
Computer Equipment [Member]
Property, Plant and Equipment [Line Items]
Property, plant and equipment, useful life	3 years
Leasehold Improvements [Member]
Property, Plant and Equipment [Line Items]
Leasehold improvements	5 or lease term,whichever is shorter
Software [Member]
Property, Plant and Equipment [Line Items]
Property, plant and equipment, useful life	3 years

Recent Accounting Pronouncements - Additional Information (Detail) $ in Millions	Dec. 31, 2021 USD ($)
Minimum [Member]
New Accounting Pronouncements Or Change In Accounting Principle [Line Items]
Lessee, operating lease, term of contract	12 months
ASC 842 Topic [Member]
New Accounting Pronouncements Or Change In Accounting Principle [Line Items]
Expected operating lease liability	$ 1.9
Expected right-of-use asset	$ 1.9
ASC 842 Topic [Member] \| Minimum [Member]
New Accounting Pronouncements Or Change In Accounting Principle [Line Items]
Lessee, operating lease, term of contract	12 months

Commitments and Contingencies - Additional Information (Detail) - USD ($)		12 Months Ended
	Jan. 01, 2019	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Other Commitments [Line Items]
Operating lease year of expiration	2026
Operating lease rental expense		$ 600,000	$ 200,000
Accrued contingent liabilities		$ 0	$ 0
Maximum [Member]
Other Commitments [Line Items]
Operating lease rental expense				$ 100,000
Royalty Agreement with Certain Members of the Surgeon Advisory Board [Member]
Other Commitments [Line Items]
Period over which the royalties are payable		3 years	3 years
Notice period for termination of agreement		90 days	90 days
Royalty Agreement with Certain Members of the Surgeon Advisory Board [Member] \| 10 Years from the First Sale of the Commercial Product [Member]
Other Commitments [Line Items]
Royalty expenses		$ 4,300,000	$ 2,400,000	$ 1,700,000
Royalty as a percentage of net sales for the period		4.60%	4.10%	4.30%
Royalty Agreement with Certain Members of the Surgeon Advisory Board [Member] \| 10 Years from the First Sale of the Commercial Product [Member] \| Maximum [Member]
Other Commitments [Line Items]
Royalty as a percentage of net sales		3.00%	3.00%
Royalty Agreement with Certain Members of the Surgeon Advisory Board [Member] \| 10 Years from the First Sale of the Commercial Product [Member] \| Minimum [Member]
Other Commitments [Line Items]
Royalty as a percentage of net sales		0.50%	0.50%

Fair Value Measurements - Summary of Assets and Liabilities Measured at Fair Value on Recurring Basis (Detail) - USD ($) $ in Thousands	Dec. 31, 2021	Dec. 31, 2020
Liabilities:
Derivative liability	$ 200
Fair Value, Recurring [Member]
Assets:
Money market funds	105,220	$ 17,577
Total	105,220	17,577
Liabilities:
Derivative liability	173	245
Total	173	245
Fair Value, Recurring [Member] \| Level 1 [Member]
Assets:
Money market funds	105,220	17,577
Total	105,220	17,577
Fair Value, Recurring [Member] \| Level 3 [Member]
Liabilities:
Derivative liability	173	245
Total	$ 173	$ 245

Fair Value Measurements - Additional Information (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Derivative liability	$ 200
Other Expense [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Change in fair value	$ 100	$ 0
Minimum [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Probability of default	1.00%
Maximum [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Probability of default	2.00%

Fair Value Measurements - Summary of the Changes in the Fair Value of the Company's Financial Instruments (Detail) - Derivative [Member] - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Fair value, beginning balance	$ 245
Initial fair value of derivative liability		$ 245
Change in fair value included in other expense, net	(72)
Fair value, ending balance	$ 173	$ 245

Balance Sheet Components - Summary of Cash and Cash Equivalents (Detail) - USD ($) $ in Thousands	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Balance Sheet Related Disclosures [Abstract]
Cash	$ 613	$ 502
Money market funds	105,220	17,577
Total cash and cash equivalents	$ 105,833	$ 18,079	$ 12,139	$ 1,284

Balance Sheet Components - Summary of Property and Equipment, Net (Detail) - USD ($) $ in Thousands	Dec. 31, 2021	Dec. 31, 2020
Property, Plant and Equipment [Line Items]
Total property and equipment	$ 5,588	$ 3,465
Less: accumulated depreciation and amortization	(2,739)	(2,636)
Property and equipment, net	2,849	829
Furniture and Fixtures, and Equipment [Member]
Property, Plant and Equipment [Line Items]
Total property and equipment	180	131
Construction in Progress [Member]
Property, Plant and Equipment [Line Items]
Total property and equipment	126
Machinery and Equipment [Member]
Property, Plant and Equipment [Line Items]
Total property and equipment	274	226
Capitalized Surgical Equipment [Member]
Property, Plant and Equipment [Line Items]
Total property and equipment	4,442	2,652
Computer Equipment [Member]
Property, Plant and Equipment [Line Items]
Total property and equipment	160	150
Leasehold Improvements [Member]
Property, Plant and Equipment [Line Items]
Total property and equipment	268	168
Software [Member]
Property, Plant and Equipment [Line Items]
Total property and equipment	$ 138	$ 138

Balance Sheet Components - Summary of Accrued Liabilities (Detail) - USD ($) $ in Thousands	Dec. 31, 2021	Dec. 31, 2020
Balance Sheet Related Disclosures [Abstract]
Accrued royalties expense	$ 1,522	$ 1,032
Accrued interest	975
Accrued professional services	941	375
Other accrued expense	1,080	441
Total accrued liabilities	$ 4,518	$ 1,848

Long Term Debt - Summary of Long-term Debt Instruments (Detail) - USD ($) $ in Thousands	Dec. 31, 2021	Dec. 31, 2020
Debt Instrument [Line Items]
Total term loans	$ 30,000	$ 31,788
Less: Unamortized debt discount and debt issuance costs	(635)	(811)
Total short-term and long-term debt	29,365	30,977
Short-term debt		1,788
Long-term debt	29,365	29,189
Term Loans [Member] \| CRG Term Loan Facility [Member]
Debt Instrument [Line Items]
Total term loans	$ 30,000	30,000
Term Loans [Member] \| Paycheck Protection Programme Loan [Member]
Debt Instrument [Line Items]
Total term loans		$ 1,788

Commitments and Contingencies - Schedule of Future Minimum Rental Obligations Required Under Non-cancelable Leases (Detail) $ in Thousands	Dec. 31, 2021 USD ($)
Commitments And Contingencies Disclosure [Abstract]
2022	$ 627
2023	444
2024	458
2025	472
2026	321
Total minimum lease payments	$ 2,322

Income Taxes - Summary of Tax Effects of Temporary Differences and Carryforwards to Significant Portions of Deferred Tax Assets (Detail) - USD ($) $ in Thousands	Dec. 31, 2021	Dec. 31, 2020
Components of the deferred tax assets
Net operating loss carryforwards	$ 8,264	$ 3,703
Interest expense	1,025
Stock option compensation expense	456	672
Accrued bonus	726	244
Research and development credits	717	475
Other	753	407
Total deferred tax assets	11,941	5,501
Deferred tax asset valuation allowance	(11,941)	(5,501)
Net deferred tax assets	$ 0	$ 0

Warrants for Class A Common Stock - Additional Information (Detail) - USD ($) $ / shares in Units, $ in Millions		12 Months Ended
	Apr. 28, 2021	Dec. 31, 2021	Dec. 31, 2019	Jul. 31, 2020	Feb. 14, 2019
Class Of Warrant Or Right [Line Items]
Class of warrants or rights number of shares issuable on conversion of warrants					713,330
Warrants expiration period			10 years
Exercise price of warrants			$ 4.0224
Estimated fair value of warrants on date of issuance			$ 0.6
Method used to determine the grant date fair value of warrants		Black-Scholes option pricing model	Black-Scholes option pricing model
Revolving Credit Facility [Member]
Class Of Warrant Or Right [Line Items]
Prior business day closing price of share	$ 31.27
Common Stock [Member] \| Warrant [Member] \| Revolving Credit Facility [Member]
Class Of Warrant Or Right [Line Items]
Number of shares issued for conversion of warrants	621,570
Tranche 3 [Member]
Class Of Warrant Or Right [Line Items]
Class of warrants or rights number of shares issuable on conversion of warrants			89,168
Terminated Tranche 3 [Member]
Class Of Warrant Or Right [Line Items]
Class of warrants or rights number of shares issuable on conversion of warrants				89,168
Maximum [Member]
Class Of Warrant Or Right [Line Items]
Class of warrants or rights number of shares issuable on conversion of warrants			713,330

Stockholders' Equity - Summary of the Company had Reserved Shares of Common Stock for Future Issuances (Detail) - shares	Dec. 31, 2021	Apr. 21, 2021	Dec. 31, 2020
Shares Reserved For Future Issuance [Line Items]
Common stock available for future issuance	11,745,544		30,508,135
Series A Convertible Preferred Stock [Member]
Shares Reserved For Future Issuance [Line Items]
Series A convertible preferred stock outstanding			6,687,475
Warrants to purchase Class A common stock [Member]
Shares Reserved For Future Issuance [Line Items]
Common stock available for future issuance			713,330
Unvested restricted stock units under 2021 Plan [Member]
Shares Reserved For Future Issuance [Line Items]
Common stock available for future issuance	10,000
Class A common stock available for future grants [Member]
Shares Reserved For Future Issuance [Line Items]
Common stock available for future grants			13,691,186
Class B common stock available for future issuance [Member]
Shares Reserved For Future Issuance [Line Items]
Common stock available for future grants			1,000,000
Common stock available for Employee Stock Purchase Plan [Member]
Shares Reserved For Future Issuance [Line Items]
Common stock available for future issuance	504,627
Common stock options issued and outstanding [Member]
Shares Reserved For Future Issuance [Line Items]
Common stock available for future issuance	7,464,580		8,081,828
Estimated preferred share conversion for dividends in kind [Member]
Shares Reserved For Future Issuance [Line Items]
Series A convertible preferred stock outstanding			334,316
2021 Incentive Award Plan [Member]
Shares Reserved For Future Issuance [Line Items]
Common stock available for future issuance	3,766,337	5,046,278

Employee Benefit Plan - Additional Information (Detail) $ in Millions	12 Months Ended
	Dec. 31, 2021 USD ($)
Defined Contribution Plan Disclosure [Line Items]
Defined contribution plan, percent of match	100.00%
Employees matching pre tax salary contribution percent	3.00%
Employees matching additional contribution percent	50.00%
Employees pre tax salary maximum matching contribution percent	5.00%
Elective deferrals and matching contributions eligibility period	3 months
Employer profit sharing contributions eligibility service period	1 year
Description of employee contributions to 401(K) plan	Effective as of January 2021, the Company began sponsoring a 401(k) profits sharing plan trust for its employees who satisfy certain eligibility requirements. An employee will be eligible to become a participant in the plan for purposes of 1) elective deferrals and matching contributions after completing 3 consecutive months of service beginning on the employee’s date of hire and 2) employer profit sharing contributions after completing 1 year of service.
Participants vest matching contributions period	90 days
Contribution to retirement plans	$ 0.7
Minimum [Member]
Defined Contribution Plan Disclosure [Line Items]
Graded vesting schedule period	1 year
Maximum [Member]
Defined Contribution Plan Disclosure [Line Items]
Graded vesting schedule period	6 years

Subsequent Events - Additional Information (Detail) - Subsequent Event [Member]	Feb. 09, 2022 ft² $ / ft²
Subsequent Event [Line Items]
Term of contract	10 years
Area of land \| ft²	125,562
Rent per square foot	22.60
Maximum rent per square foot for last 12 months of lease term	27.00