Stock-Benefit Plans and Equity Transactions (Tables)

3 Months Ended

Mar. 31, 2022

Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]

Summary of Total Stock Based Compensation

The Company has stock-based compensation plans under which it grants stock options, RSUs, and PRSUs to officers, directors and third parties. Total stock-based compensation for the periods presented were as follows (in thousands):

	Three Months Ended
	March 31,
	2022		2021
Cost of sales	$	256	$	95
Research and development		972		498
Sales, general and administrative		8,956		3,881
Total	$	10,184	$	4,474

Schedule of Assumptions used to Estimate Fair Value of Stock Options Granted and Stock Purchase Rights under ESPP

The Company estimates the fair value of shares issued to employees under the ESPP using the Black-Scholes option-pricing model. The assumptions used to estimate the fair value of stock options granted and stock purchase rights under the ESPP are as follows:

	Three Months Ended
	March 31,
	2022			2021
Risk-free interest rate		0.07	%		0.10	%
Expected dividend yield		—			—
Expected term (years)		0.50			0.50
Volatility		50.29	%		78.51	%

Summary of All Outstanding Warrants for Common Stock

A summary of all outstanding warrants for common stock as of March 31, 2022, were as follows (in thousands, except for strike price data):

	Number of Warrants		Strike Price		Expiration
2017 PIPE Warrants		1,887	$	2.00	June 2022
2018 PIPE Warrants		8,354	$	3.50	May 2023
SafeOp Surgical Merger Warrants		1,195	$	3.50	May 2023
2018 Squadron Medical Warrants		845	$	3.15	May 2027
2019 Squadron Medical Warrants		4,839	$	2.17	May 2027
2020 Squadron Medical Warrants		1,076	$	4.88	May 2027
Executive Warrants		1,327	$	5.00	December 2022
Other(1)		131	$	5.74	Various through February 2026
Total		19,654

(1) Weighted-average strike price.