Organization and Basis of Presentation (Details)									1 Months Ended	3 Months Ended		6 Months Ended			15 Months Ended
	Aug. 05, 2020 USD ($)	May 22, 2020 USD ($)	Mar. 23, 2020 USD ($)	Mar. 20, 2020 employee	Sep. 30, 2019 USD ($) milestone	Jun. 25, 2019 USD ($)	Dec. 17, 2018 USD ($) $ / shares shares	May 10, 2017 USD ($)	Jan. 31, 2017 USD ($)	Jun. 30, 2020 USD ($)	Jun. 30, 2019 USD ($)	Dec. 31, 2020 USD ($)	Jun. 30, 2020 USD ($) shares	Jun. 30, 2019 USD ($)	Mar. 31, 2020 USD ($) shares	Apr. 01, 2021 USD ($)	Jan. 01, 2021 USD ($)	Jul. 01, 2020 USD ($)	Apr. 17, 2020 USD ($)	Dec. 31, 2019 USD ($)
Line of Credit Facility [Line Items]
Accumulated deficit										$ (515,633,000)			$ (515,633,000)							$ (504,145,000)
Cash and cash equivalents and investments										18,200,000			18,200,000
Restricted cash										500,000			500,000							$ 500,000
Number of employees furloughed | employee				80
Amount of equity able to raise			$ 200,000,000						$ 200,000,000
Maximum offering price								$ 50,000,000
Net proceeds from issuance of common stock													2,024,000	$ 3,000,000
Issuance of common stock											$ 3,000,000			3,000,000
Total revenue										19,468,000	19,593,000		$ 35,943,000	40,237,000
Equity Distribution Agreement
Line of Credit Facility [Line Items]
Number of shares sold (in shares) | shares													2,610,112
Net proceeds from issuance of common stock													$ 4,300,000
Innovatus
Line of Credit Facility [Line Items]
Issuance of common stock						$ 3,000,000
LPC Agreements
Line of Credit Facility [Line Items]
Number of shares sold (in shares) | shares															3,121,968
Net proceeds from issuance of common stock															$ 2,300,000
Number of shares issued in transaction (in shares) | shares							1,921,968
Proceeds received from sale of stock							$ 1,000,000
Premium on previous day's closing price							110.00%
Purchase period							36 months
LPC Agreements, Consideration For Commitment To Purchase Shares
Line of Credit Facility [Line Items]
Number of shares issued in transaction (in shares) | shares							354,430
Term loan | 2019 Secured Loan Agreement
Line of Credit Facility [Line Items]
Maximum borrowing capacity						$ 30,000,000
Instrumentation Technology | Howmedica Osteonics Corp
Line of Credit Facility [Line Items]
Installment payment					$ 14,000,000								2,000,000
Potential milestone payment					$ 16,000,000
Number of potential milestones | milestone					3
Royalty and licensing
Line of Credit Facility [Line Items]
Total revenue										9,725,000	$ 256,000		$ 9,910,000	$ 431,000
Maximum | LPC Agreements
Line of Credit Facility [Line Items]
Value of stock to be sold							$ 20,000,000
Minimum | LPC Agreements
Line of Credit Facility [Line Items]
Sale of stock (in usd per share) | $ / shares							$ 0.25
Paycheck Protection Program Note
Line of Credit Facility [Line Items]
Debt instrument principal																			$ 4,700,000
Subsequent Event | Cowen Sales Agreement
Line of Credit Facility [Line Items]
Amount of equity able to raise	$ 25,000,000
Broker commissions	3.00%
Subsequent Event | Term loan | 2019 Secured Loan Agreement
Line of Credit Facility [Line Items]
Minimum cash on hand																		$ 5,000,000
Forecast | Subsequent Event | Term loan | 2019 Secured Loan Agreement
Line of Credit Facility [Line Items]
Minimum cash on hand																	$ 10,000,000
Minimum gross cash proceeds												$ 20,000,000.0
Maximum outstanding indebtedness																$ 5,000,000.0	$ 2,500,000.0
Conformis v Zimmer Biomet | Positive Outcome of Litigation
Line of Credit Facility [Line Items]
Proceeds from legal settlements		$ 3,500,000
Total amount awarded		$ 9,600,000
Zimmer Biomet | Royalty and licensing
Line of Credit Facility [Line Items]
Total revenue										$ 9,600,000