Property and Equipment, Net - Schedule of Property and Equipment, Net (Details) - USD ($) $ in Thousands	Mar. 31, 2019	Dec. 31, 2018
Property, Plant and Equipment [Line Items]
Total cost	$ 19,982	$ 20,083
Less: accumulated depreciation	(13,600)	(12,909)
Property and equipment, net	6,382	7,174
Equipment [Member]
Property, Plant and Equipment [Line Items]
Total cost	4,105	4,145
Computer Equipment [Member]
Property, Plant and Equipment [Line Items]
Total cost	450	481
Computer Software [Member]
Property, Plant and Equipment [Line Items]
Total cost	570	570
Furniture and Fixtures [Member]
Property, Plant and Equipment [Line Items]
Total cost	99	164
Leasehold Improvements [Member]
Property, Plant and Equipment [Line Items]
Total cost	3,941	3,941
Vehicles [Member]
Property, Plant and Equipment [Line Items]
Total cost	10	10
Surgical Instruments [Member]
Property, Plant and Equipment [Line Items]
Total cost	$ 10,807	$ 10,772