The Company and Basis of Presentation - Additional Information (Details) - USD ($) $ / shares in Units, $ in Thousands				3 Months Ended		9 Months Ended
	Aug. 02, 2019	Mar. 27, 2019	Nov. 06, 2018	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018	Dec. 31, 2018
Company And Basis Of Presentation [Line Items]
Net proceeds from offering						$ 2,073	$ 51,554
Working capital				$ 85,800		85,800
Cash				57,843		57,843		$ 29,054
Minimum liquidity covenant amount				5,000		$ 5,000
Latest effective date of minimum liquidity covenant						2020-03
Depreciation				1,800	$ 1,500	$ 4,800	4,500
Reclassification | Surgical instruments
Company And Basis Of Presentation [Line Items]
Depreciation					$ 1,300		$ 3,900
Squadron Credit Agreement
Company And Basis Of Presentation [Line Items]
Debt instrument, maturity date		Nov. 30, 2023	Nov. 30, 2023
Term Loan | Squadron Credit Agreement
Company And Basis Of Presentation [Line Items]
Secured debt agreement			$ 35,000	$ 20,000		$ 20,000
Debt instrument, maturity date						Dec. 31, 2020
Common Stock
Company And Basis Of Presentation [Line Items]
Common stock issued				12,535,000
Underwritten Public Offering
Company And Basis Of Presentation [Line Items]
Net proceeds from offering	$ 54,000
Underwritten Public Offering | Common Stock
Company And Basis Of Presentation [Line Items]
Common stock issued	12,535,000
Shares issued price per share	$ 4.60
Shares issued of underwriters option to purchase additional shares	1,635,000