Summary of Significant Accounting Policies (Policies)	12 Months Ended
Summary of Significant Accounting Policies (Policies)	Dec. 31, 2018
Summary of Significant Accounting Policies
Cash and Cash Equivalents and Concentration	Cash and Cash Equivalents and Concentration The Company considers highly liquid investments with maturities of three months or less at the date of acquisition as cash equivalents in the accompanying Consolidated Financial Statements. The Company has not experienced any losses related to these balances; however, as of December 31, 2018, $23,794 of the cash and cash equivalents balance was in excess of FDIC limits. As of December 31, 2018, the Company had restricted cash balances of $6,000 as collateral for an irrevocable standby letter of credit. There were no restricted cash balances as of December 31, 2017.
Investments	Investments The Company invests primarily in U.S. Government securities, corporate bonds, commercial paper and asset-backed securities and classifies all investments as available-for-sale. Investments are recorded at fair value. The Company has elected the fair value option (FVO) for all of its available-for-sale investments. The FVO election results in all changes in unrealized gains and losses being included in investment income in the Consolidated Statements of Operations.
Revenue Recognition	Revenue Recognition On January 1, 2018, the Company adopted Financial Accounting Standards Board (FASB) Accounting Standards Codification (ASC) No. 606, “Revenue from Contracts with Customers”, utilizing the modified retrospective method applied to contracts that were not completed. The adoption of the standard did not have a material impact on the timing and amounts of the Company’s revenue, processes or internal controls. Upon adoption, the Company did not have any material remaining performance obligations, significant judgements, or material costs to obtain or fulfill contracts with its customers. The Company enters into contracts to sell and distribute products and services to hospitals and surgical facilities for use in caring for patients with peripheral nerve damage or transection. Revenue is recognized when the Company has met its performance obligations pursuant to its contracts with its customers in an amount that the Company expects to be entitled to in exchange for the transfer of control of the products and services to the Company’s customers. In the case of products or services sold to a customer under a distribution or purchase agreement, the Company has no further performance obligations and revenue is recognized at the point control transfers which occurs either when: i) the product is shipped via common carrier; or ii) the product is delivered to the customer or distributor, in accordance with the terms of the agreement. A portion of the Company's product revenue is generated from consigned inventory maintained at hospitals and independent sales agencies, and also from inventory physically held by field sales representatives. For these types of products sales, the Company retains control until the product has been used or implanted, at which time revenue is recognized. The Company elected to account for shipping and handling activities as a fulfillment cost rather than a separate performance obligation. Amounts billed to customers for shipping and handling are included as part of the transaction price and recognized as revenue when control of the underlying products is transferred to the customer. The related shipping and freight charges incurred by the Company are included in cost of sales. The Company operates in a single reportable segment of peripheral nerve repair, offers similar products to its customers, and enters into consistently structured arrangements with similar types of customers. As such, the Company does not disaggregate revenue from contracts with customers as the nature, amount, timing and uncertainty of revenue and cash flows does not materially differ within and among the contracts with customers. The contract with the customer states the final terms of the sale, including the description, quantity, and price of each implant distributed. The payment terms and conditions in the Company’s contracts vary; however, as a common business practice, payment terms are typically due in full within 30 to 60 days of delivery. Since the customer agrees to a stated price in the contract that does not vary over the contract term, the contracts do not contain any material types of variable consideration, and contractual rights of return are not material. The Company has several contracts with distributors in international markets which include consideration paid to the customer in exchange for distinct marketing and other services. The Company records such consideration paid to the customer as a reduction to revenue from the contracts with those distributor customers.
Allowance for Doubtful Accounts Receivable and Concentration of Credit Risk	Allowance for Doubtful Accounts Receivable and Concentration of Credit Risk The Company evaluates the collectability of accounts receivable to determine the appropriate allowance for doubtful accounts. In determining the amount of the allowance, the Company considers aging of account balances, historical credit losses, customer-specific information and other relevant factors. An increase to the allowance for doubtful accounts results in a corresponding increase in general and administrative expense. The Company reviews accounts receivable and adjusts the allowance based on current circumstances and charges off uncollectible receivables against the allowance when all attempts to collect the receivable have failed. The Company’s history of write-offs has not been significant. The allowance for doubtful accounts balance was approximately $1,117 and $461 at December 31, 2018 and 2017, respectively. Concentrations of credit risk with respect to accounts receivable are limited because a large number of geographically diverse customers make up the Company’s customer base, thus spreading the trade credit risk. The Company also controls credit risk through credit approvals and monitoring procedures.
Inventories	Inventories Inventories are comprised of unprocessed tissue, work-in-process, Avance® Nerve Graft, Axoguard® Nerve Connector, Axoguard® Nerve Protector, Avive® Soft Tissue Membrane, Acroval® Neurosensory and Motor Testing System, Axotouch® Two-Point Discriminator and supplies and are valued at the lower of cost (first-in, first-out) or net realizable value. The Company monitors the shelf life of its products and historical expiration and spoilage trends, and writes-down inventory based on the estimated amount of inventory that will not be distributed before expiration or spoilage.
Deferred Financing Costs	Deferred Financing Costs The Company records as a discount to debt all third-party costs associated with the issuance of long-term debt. The costs are amortized to interest expense over the term of the debt using the effective interest method.
Net Loss Per Share	Net Loss Per Share Basic and diluted net loss per share is computed in accordance with FASB ASC 260, “Earnings Per Share” (ASC 260), by dividing the net loss by the weighted average number of common shares outstanding during the period. Since the Company has experienced net losses for all periods presented, options and awards of 2,621,440, 2,253,399 and 1,177,456 which were outstanding as of December 31, 2018, 2017 and 2016, respectively, were not included in the computation of diluted Eps because dilutive shares are not factored into the calculation of EPS when a loss applicable to common shares as they would be anti-dilutive.
Advertising	Advertising Advertising costs are expensed as incurred. Advertising costs were $29, $204 and $40 for the years ended December 31, 2018, 2017 and 2016, respectively, and are included in sales and marketing expense on the accompanying Consolidated Statements of Operations.
Research and Development Costs	Research and Development Costs Research and development costs are expensed as incurred and were $11,773, $6,699 and $4,212 for the years ended December 31, 2018, 2017 and 2016, respectively.
Use of Estimates	Use of Estimates The preparation of consolidated financial statements in conformity with accounting principles generally accepted in the United States of America requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities at the date of the consolidated financial statements and the reported amounts of revenues and expenses during the reporting period. Management believes the critical accounting policies regarding revenue recognition, allowance for uncollectible accounts receivable, investments, inventories and share-based employee compensation affect our more significant judgments and estimates used in the preparation of the Company’s consolidated financial statements. Actual results could differ materially from those estimates.
Stock-Based Compensation	Stock-Based Compensation The Company measures all employee stock-based compensation awards using the fair value, including stock options, restricted stock, performance stock and stock purchases related to an employee stock purchase plan. The share-based compensation recognized under ASC 718 for years ended December 31, 2018, 2017 and 2016 was $7,606, $3,609, and $1,390, respectively. ASC 718 requires companies to estimate the fair value of share-based payment awards on the date of grant using an option-pricing model. The value of the portion of the award that is ultimately expected to vest is recognized as expense over the requisite service periods in the Company’s Consolidated Statements of Operations. The expense has been reduced for forfeitures as they occur. The Company estimates the fair value of time-based options on the date of grant using the Multi-Point Black-Scholes option-pricing model (Black-Scholes model). The Company’s determination of fair value is affected by the Company’s stock price, as well as assumptions regarding several subjective variables. These variables include, but are not limited to, the Company’s expected stock price volatility over the term of the awards. The Company estimates the fair value of restricted stock based upon the grant date closing market price of the Company’s common stock. The Company also has an employee stock purchase plan (ESPP) which is available to all eligible employees as defined by the plan document. Under the ESPP, shares of the Company’s common stock may be purchased at a discount. The Company estimates the number of shares to be purchased under the ESPP at the beginning of each purchase period based upon the fair value of the stock at the beginning of the purchase period using the Black-Scholes model and records estimated compensation expense during the period. Expense is adjusted at the time of stock purchase. With respect to performance stock units (“PSUs”), the number of shares that vest and are issued to the recipient is based upon the Company’s performance as measured against specified targets over the measurement period. The fair value of the PSUs is based on the Company’s closing stock price on the grant date and its estimate of achieving such performance targets. For further discussion and disclosures, see Note 11 – Equity Compensation Plans.
Recent Accounting Pronouncements	Recent Accounting Pronouncements In May 2014, the FASB issued a new standard on revenue recognition which outlines a single comprehensive model to use in accounting for revenue arising from contracts with customers and supersedes most current revenue recognition guidance, including industry-specific guidance. The core principle of the revenue model is that an entity should recognize revenue to depict the transfer of promised goods or services to customers in an amount that reflects the consideration to which the entity expects to be entitled in exchange for those goods or services. The standard was designed to create greater comparability for financial statement users across industries and jurisdictions and also requires enhanced disclosures. The standard could be applied retrospectively to each prior period presented or by use of the modified retrospective method with the cumulative effect recognized as of the adoption date. The Company adopted the standard on January 1, 2018 utilizing the modified retrospective method. The adoption of this standard did not have a material impact on the Company’s consolidated financial statements, other than the enhanced disclosure included in the notes herein. In February 2016, the FASB issued ASU No. 2016-02, Leases (Topic 842). This update will increase transparency and comparability among organizations by recognizing lease assets and lease liabilities on the balance sheet and disclosing key information about leasing arrangements. This update is effective for annual and interim reporting periods beginning after December 15, 2018, including interim periods within those fiscal years. Early adoption is permitted. In July 2018, the FASB issued ASU No. 2018-11, Targeted Improvements to ASC 842, Leases. ASU 2018-11 provided entities with an alternative modified transition method to elect not to recast the comparative periods presented when adopting ASC 842. The new standard provides a number of optional practical expedients in transition. The Company expects to elect: (1) the ‘package of practical expedients’, which permits it not to reassess under the new standard its prior conclusions about lease identification, lease classification, and initial direct costs and (2) the use-of-hindsight. In addition, the new standard provides practical expedients for an entity’s ongoing accounting that the Company anticipates making, such as the (1) the election for certain classes of underlying asset to not separate non-lease components from lease components and (2) the election for short-term lease recognition exemption for all leases that qualify. The Company will adopt ASU 842 as of January 1, 2019, using the alternative modified transition method. In preparation of adopting ASC 842, the Company is implementing additional internal controls to enable future preparation of financial information in accordance with ASC 842. The Company has also substantially completed its evaluation of the impact on the Company’s lease portfolio. The Company believes the largest impact will be on the consolidated balance sheets for the accounting of facilities-related leases, which represents a majority of its operating leases it has entered into as a lessee. These leases will be recognized under the new standard as right of use assets (“ROU”) and operating lease liabilities. The Company will also be required to provide expanded disclosures for its leasing arrangements. As of December 31, 2018, the Company had $43,579 of undiscounted future minimum operating lease commitments that are not recognized on its consolidated balance sheets as determined under the current standard. For a lessee, the results of operations are not expected to significantly change after adoption of the new standard. While substantially complete, the Company is still in the process of finalizing its evaluation of the effect of ASU 842 on the Company’s financial statements and disclosures, including the determination of the Company’s incremental borrowing rate for each of the operating leases to estimate the interest rate we would have to pay to borrow on a collateralized basis over a similar term for an amount equal to the lease payments. The Company will finalize its accounting assessment and quantitative impact of the adoption during the first quarter of fiscal year 2019. In August 2016, the FASB issued ASU No. 2016-15, Classification of Certain Cash Receipts and Cash Payments (Topic 230). The ASU was issued intending to reduce diversity in practice in how certain cash receipts and cash payments are presented and classified in the Consolidated Statement of Cash Flows by providing guidance on eight specific cash flow issues. We retrospectively adopted the standard on January 1, 2018. The adoption of this standard did not have a material impact on the Company’s consolidated financial statements. In November 2016, the FASB issued ASU No. 2016-18, Statement of Cash Flows (Topic 230), guidance that a statement of cash flows explains the change during the period in the total of cash, cash equivalents, and amounts generally described as restricted cash or restricted cash equivalents. We retrospectively adopted the standard on January 1, 2018. The adoption of this standard did not have a material impact on the Company’s Consolidated Statement of Cash Flows. In May 2017, the FASB issued ASU No. 2017-09, Compensation – Stock Compensation (Topic 718): Scope of Modification Accounting. ASU 2017-09 provides clarity on which changes to the terms or conditions of share-based payment awards require entities to apply the modification accounting provisions required in Topic 718. We retrospectively adopted the standard on January 1, 2018. The adoption of this standard did not have a material impact on the Company’s consolidated financial statements. In June 2018, the FASB issued ASU No. 2018-07, which supersedes ASC 505-50 and expands the scope of ASC 718 to include all share-based payment arrangements related to the acquisition of goods and services from both nonemployees and employees. As result, most of the guidance in ASC 718 associated with employee share-based payments, including most of its requirements related to classification and measurement, applies to nonemployee share-based payment arrangements. This update is effective for annual and interim reporting periods beginning after December 15, 2018, including interim periods within those fiscal years. Early adoption is permitted. We do not expect this standard will have a material impact on the Company’s consolidated financial statements. In August 2018, the FASB issued ASU No. 2018-15, Guidance on Cloud Computing Arrangements. ASU 2018-15 provides guidance on implementation costs incurred in a cloud computing arrangement (CCA) that is a service contract and aligns the accounting for such costs with the guidance on capitalizing costs associated with developing or obtaining internal-use software. Specifically, the ASU amends ASC 350 to include in its scope implementation costs of a CCA that is a service contract and clarifies that a customer should apply ASC 350-40 to determine which implementation costs should be capitalized. This update is effective for annual and interim reporting periods beginning after December 15, 2019, including interim periods within those fiscal years. Early adoption is permitted. The Company is currently evaluating the impact this standard will have on the Company’s consolidated financial statements. The Company’s management has reviewed and considered all other recent accounting pronouncements and believe there are none that could potentially have a material impact on the Company’s consolidated financial condition, results of operations, or disclosures.