Stock Benefit Plans and Equity Transactions - Summary of All Outstanding Warrants for Common Stock (Details)	9 Months Ended
	Sep. 30, 2020 $ / shares shares
Class Of Warrant Or Right [Line Items]
Number of Warrants	25,357,576
2017 PIPE Warrants
Class Of Warrant Or Right [Line Items]
Number of Warrants	3,255,554
Strike Price | $ / shares	$ 2.02
Expiration	June 2022
2018 PIPE Warrants
Class Of Warrant Or Right [Line Items]
Number of Warrants	11,527,147
Strike Price | $ / shares	$ 3.50
Expiration	May 2023
SafeOp Surgical Merger Warrants
Class Of Warrant Or Right [Line Items]
Number of Warrants	2,185,099
Strike Price | $ / shares	$ 3.50
Expiration	May 2023
2018 Squadron Capital Warrants
Class Of Warrant Or Right [Line Items]
Number of Warrants	845,000
Strike Price | $ / shares	$ 3.15
Expiration	May 2027
2019 Squadron Capital Warrants
Class Of Warrant Or Right [Line Items]
Number of Warrants	4,838,710
Strike Price | $ / shares	$ 2.17
Expiration	May 2027
2020 Squadron Capital Warrants
Class Of Warrant Or Right [Line Items]
Number of Warrants	1,075,820
Strike Price | $ / shares	$ 4.88
Expiration	May 2027
Executive Warrants
Class Of Warrant Or Right [Line Items]
Number of Warrants	1,327,434
Strike Price | $ / shares	$ 5.00
Expiration	December 2022
Other Warrants
Class Of Warrant Or Right [Line Items]
Number of Warrants	302,812
Strike Price | $ / shares	$ 3.85
Expiration	Various through May 2023