The Company accounts for a contract when there is approval and commitment from both parties, the rights of the parties are identified, payment terms are identified, the contract has commercial substance, and collectability of consideration is probable. The Company’s contracts may contain one or more performance obligations. If a contract contains more than one performance obligation, the Company allocates the total transaction price to each of the performance obligations based upon the observable standalone selling price of the promised goods or services underlying each performance obligation. The Company recognizes

revenue when control of the promised goods or services is transferred to the customer, which typically occurs at a point in time upon shipment, delivery, or utilization, in an amount that reflects the consideration which the Company expects to be entitled in exchange for the promised goods or services. The amount the Company expects to be entitled to in exchange for the goods or services reflects any fixed amount stated per the contract and estimates for any variable consideration, such as discounts, to the extent that is it probable that a significant reversal of cumulative revenue recognized will not occur when the uncertainty associated with the variable consideration is resolved.

The following sections discuss the Company’s revenue recognition policies by significant product category:

Bone Growth Therapies revenue is largely attributable to the U.S. and is comprised of third-party payor transactions and wholesale revenue.

The largest portion of Bone Growth Therapies revenue is derived from third-party payors. This includes commercial insurance carriers, health maintenance organizations, preferred provider organizations, and governmental payors, such as Medicare. Revenue is recognized when the product is fitted to and accepted by the patient and all applicable documents required by the third-party payor have been obtained. Amounts paid by third-party payors are generally based on fixed or allowable reimbursement rates. These revenues are recorded at the expected or preauthorized reimbursement rates, net of any contractual allowances or adjustments. Certain billings are subject to review by the third-party payors and may be subject to adjustment.

Wholesale revenue is related to the sale of the Company’s bone growth stimulators directly to durable medical equipment suppliers. Wholesale revenues are typically recognized upon shipment and receipt of a confirming purchase order, which is when the customer obtains control of the promised goods.

Biologics revenue is largely attributable to the U.S. and is primarily related to a collaborative arrangement with MTF, which extends through July 28, 2027. Under this arrangement, the Company markets tissue for bone repair and reconstruction under the brand names Trinity Evolution and Trinity ELITE. Per the terms of the agreement, MTF sources the tissue, processes it to create the bone growth matrix, packages, and delivers the tissue to the customer. The Company has exclusive global marketing rights for the Trinity Evolution and Trinity ELITE tissues, exclusive rights to market fiberFUSE and AlloQuent tissues in the U.S., non-exclusive marketing rights for certain other products, and receives marketing fees from MTF based on total sales. MTF is considered the primary obligor in these arrangements; therefore, the Company recognizes marketing service fees on a net basis within net sales upon shipment of the product to the customer.

Spinal Implants and Global Extremities products are distributed world-wide, with U.S. sales largely comprised of commercial sales and international sales derived from both commercial sales and through stocking distributor arrangements.

Commercial revenue is largely related to the sale of the Company’s Spinal Implants and Global Extremities products to hospital customers. The customer obtains control and revenues are recognized when these products have been utilized and a confirming purchase order has been received from the hospital.

Other revenues within the Spinal Implants and Global Extremities product categories are derived from stocking distributors, who purchase the Company’s products and then re-sell them directly to customers, such as hospitals. For revenue from stocking distributor arrangements, it is the Company’s policy to recognize revenue upon shipment and receipt of a confirming purchase order, which is when the distributor obtains control of the promised goods. The transaction price with stocking distributors is estimated based upon the Company’s historical collection experience with the stocking distributor. To derive this estimate, the Company analyzes twelve months of historical invoices by stocking distributor and the subsequent collections on those invoices for a period of up to 24 months subsequent to the invoice date. The historical collection percentage, which is specific to each stocking distributor, is then used to calculate the transaction price. Cost of sales is also recorded upon transfer of control of the product to the customer.

The table below presents net sales, which includes product sales and marketing service fees, for each of the years ended December 31, 2020, 2019, and 2018.

	For the year ended December 31,
(U.S. Dollars, in thousands)	2020		2019		2018
Product sales	$	353,087	$	397,064	$	395,589
Marketing service fees		53,475		62,891		57,453
Net sales	$	406,562	$	459,955	$	453,042

Product sales primarily consists of the sale of Bone Growth Therapies, Spinal Implants, and Global Extremities products. Marketing service fees are received from MTF based on total sales of biologics tissues and relates solely to the Biologics product category within the Global Spine reporting segment. Marketing service fees received from MTF were $53.5 million, or approximately 96% of total Biologics revenues, for the year ended December 31, 2020. As MTF is the Company’s single supplier for the Trinity Evolution and Trinity ELITE tissue forms, which are derived from human cadaveric donors, any event or circumstance that would impact MTF’s continued access to donated human cadaveric tissue or the Company’s ability to market these tissues may adversely impact the Company’s financial results.

Revenues exclude any value added or other local taxes, intercompany sales and trade discounts. Shipping and handling costs for products shipped to customers are included in cost of sales, and were $2.4 million, $2.8 million and $2.7 million for the years ended December 31, 2020, 2019, and 2018, respectively.

As discussed in Note 3, the Company adopted ASU No. 2016-13 - Financial Instruments—Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instruments and subsequent amendments, using a modified retrospective approach. Adoption of the new standard resulted in an increase to the Company’s allowance for expected credit losses of $1.1 million, an increase in deferred income tax assets of $0.2 million, and a decrease in retained earnings of $0.9 million as of January 1, 2020. The net impact of adoption to the Company’s balance sheet as of January 1, 2020 is presented in the table below. The standard did not have a material impact to the Company’s condensed consolidated statements of operations or cash flows.

(U.S. Dollars, in thousands)	December 31, 2019			Impact of Adoption of ASC 326			January 1, 2020
Assets
Current assets
Cash, cash equivalents, and restricted cash	$	70,403		$	—		$	70,403
Accounts receivable, net		86,805			(1,120	)		85,685
Inventories		82,397			—			82,397
Prepaid expenses and other current assets		20,948			—			20,948
Total current assets		260,553			(1,120	)		259,433
Deferred income taxes		35,117			233			35,350
Other long-term assets		199,950			—			199,950
Total assets	$	495,620		$	(887	)	$	494,733
Liabilities and shareholders’ equity
Total liabilities	$	167,989		$	—		$	167,989
Shareholders’ equity
Common shares	$	1,902		$	—		$	1,902
Additional paid-in capital		271,019			—			271,019
Retained earnings		57,749			(887	)		56,862
Accumulated other comprehensive loss		(3,039	)		—			(3,039	)
Total shareholders’ equity		327,631			(887	)		326,744
Total liabilities and shareholders’ equity	$	495,620		$	(887	)	$	494,733

Payment terms vary by the type and location of the Company’s customers and the products or services offered. The term between invoicing and when payment is due is not significant. Subsequent to the adoption of ASU 2016-13, the Company’s allowance for expected credit losses represents the portion of the receivable’s amortized cost basis that an entity does not expect to collect over the receivable’s contractual life, considering past events, current conditions, and reasonable and supportable forecasts of future economic conditions.

The process for estimating the ultimate collection of accounts receivable involves significant assumptions and judgments. The determination of the contractual life of accounts receivable, the aging of outstanding receivables, as well as the historical collections, write-offs, and payor reimbursement experience over the estimated contractual lives of such receivables, are integral parts of the estimation process related to reserves for expected credit losses and the establishment of contractual allowances. Accounts receivable are analyzed on a quarterly basis to assess the adequacy of both reserves for expected credit losses and contractual allowances. Revisions in allowances for expected credit loss estimates are recorded as an adjustment to bad debt expense within sales and marketing expenses. Revisions to contractual allowances are recorded as an adjustment to net sales. These estimates are periodically tested against actual collection experience. In addition, the Company analyzes its receivables by geography and by customer type, where appropriate, in developing estimates for expected credit losses.

The following table provides a detail of changes in the Company’s allowance for expected credit losses for the year ended December 31, 2020:

The Company will generally sell receivables from certain Italian hospitals each year to accelerate cash collections. During 2020, 2019, and 2018 the Company sold €8.3 million, €9.8 million, and €9.8 million ($9.6 million, $10.9 million, and $11.5 million) of receivables, respectively. The estimated related fees for 2020, 2019, and 2018 were $0.3 million, $0.3 million and $0.3 million, respectively, which is recorded as interest expense. Accounts receivables sold without recourse are removed from the balance sheet at the time of sale.

In June 2019, the Company received a payment of $1.4 million from the Administration of Medical Services of Puerto Rico, a government-owned corporation, in settlement of approximately $2.5 million of outstanding accounts receivable. This $2.5 million of outstanding accounts receivable had previously been fully reserved between the Company’s allowances for expected credit losses and contractual allowances. As a result of this settlement, and in accordance with the Company’s policy, the Company recorded the resulting adjustment to contractual allowances of $0.4 million within net sales and the recovery of the allowance for expected credit losses as a credit to bad debt expense of $1.0 million.

The Company’s contract liabilities largely relate to a prepayment of $13.9 million received in April 2020 from the CMS as part of the Accelerated and Advance Payment Program of the CARES Act intended to increase cash flow to providers of services and suppliers impacted by the COVID-19 pandemic.

On October 1, 2020, the President of the United States signed the “Continuing Appropriations Act, 2021 and Other Extensions Act,” which relaxed a number of the Medicare Accelerated and Advance Payment Programs recoupment terms for providers and suppliers that received funds from the program. Under these new terms, recoupment will be delayed until one year after payment was issued. After that first year, Medicare will automatically recoup 25% of Medicare payments otherwise owed to the provider or supplier for 11 months. At the end of the 11-month period, recoupment will increase to 50% for another 6 months. Thus, during these time periods, rather than receiving the full amount of payment for newly submitted claims, the Company’s outstanding accelerated / advance payment balance will be reduced by the recoupment amount until the full balance has been repaid.

As of December 31, 2020, the Company has classified $9.8 million of this contract liability within other current liabilities and $4.0 million within other long-term liabilities based upon the Company’s estimates of when such funds will be recouped. The Company did not recognize any net sales during the year ended December 31, 2020, respectively, attributable to the satisfaction of performance obligations related to the CMS prepayment.

The Company’s contract assets, excluding accounts receivable (“other contract assets”), largely consist of payments made to certain distributors to obtain contracts, gain access to customers in certain territories, and to provide the benefit of the exclusive distribution of the Company’s products. Other contract assets are included in other long-term assets and were $2.0 million and $3.7 million as of December 31, 2020 and 2019, respectively.

Other contract assets are amortized on a straight-line basis over the term of the related contract. No impairments were incurred for other contract assets in 2020 or 2019. Further, the Company applies the practical expedient to expense sales commissions when incurred, as the applicable amortization period would be for one year or less.