Revenue - Disaggregation of Revenue (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Disaggregation of Revenue [Line Items]
Product sales, net	$ 33,718	$ 31,020	$ 106,025	$ 77,712
Other revenue	788	1,238	2,568	1,238
Total revenue	34,506	32,258	108,593	78,950
Accounting Standards Update 2014-09 | Difference between Revenue Guidance in Effect before and after Topic 606
Disaggregation of Revenue [Line Items]
Product sales, net	153	8	(125)	695
MACI Implants and Kits, and Epicel
Disaggregation of Revenue [Line Items]
Product sales, net	33,718	31,020	106,025	77,712
NexoBid revenue
Disaggregation of Revenue [Line Items]
Other revenue	800	1,200	2,600
Through Intermediary | Implants | Contract rate
Disaggregation of Revenue [Line Items]
Product sales, net	15,149	14,897	46,547	36,084
Through Intermediary | Implants | Time-and-materials contract
Disaggregation of Revenue [Line Items]
Product sales, net	3,463	3,529	11,357	10,299
Time-and-materials contract | Implants | Time-and-materials contract
Disaggregation of Revenue [Line Items]
Product sales, net	644	782	1,901	1,793
Provider or Facility | Implants | Contract rate
Disaggregation of Revenue [Line Items]
Product sales, net	3,895	4,602	12,876	9,528
Provider or Facility | NexoBid revenue
Disaggregation of Revenue [Line Items]
Other revenue	788	1,238	2,568	1,238
Directly to consumer | Biopsy kits
Disaggregation of Revenue [Line Items]
Product sales, net	577	539	1,647	1,348
Directly to consumer | Epicel
Disaggregation of Revenue [Line Items]
Product sales, net	$ 9,837	$ 6,663	$ 31,822	$ 17,965