Consolidated Statements of Operations and Comprehensive Loss - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Income Statement [Abstract]
Revenue	$ 32,733	$ 32,595	$ 20,004
Cost of goods sold	11,531	10,181	7,718
Gross profit	21,202	22,414	12,286
Operating expenses
Research and development	7,460	6,049	6,991
Selling, general and administrative	46,074	34,203	20,347
Total operating expenses	53,534	40,252	27,338
Loss from operations	(32,332)	(17,838)	(15,052)
Interest income	213	432	21
Interest expense	(3,181)	(2,317)	(2,520)
Other income (expense), net	3,282	(617)	(916)
Net loss before tax	(32,018)	(20,340)	(18,467)
Income tax expense	213	363	12
Net loss	(32,231)	(20,703)	(18,479)
Other comprehensive income (loss)
Currency translation adjustment	318	34	126
Change in unrealized (losses) gains on marketable securities	(6)	6	0
Total other comprehensive income	312	40	126
Comprehensive loss	$ (31,919)	$ (20,663)	$ (18,353)
Net loss per share attributable to common stockholders, basic and diluted (in dollars per share)	$ (3.16)	$ (11.66)	$ (11.03)
Weighted-average shares used in computing net loss per share attributable to common stockholder, basic and diluted (in shares)	10,184,841	1,776,110	1,674,779