CONDENSED CONSOLIDATED STATEMENTS OF STOCKHOLDERS' EQUITY (Unaudited) - USD ($) $ in Thousands	Total	SafeOp Surgical, Inc.	Series A Convertible Preferred Stock	Series B Convertible Preferred Stock	Common Stock	Common Stock SafeOp Surgical, Inc.	Additional paid-in capital	Additional paid-in capital SafeOp Surgical, Inc.	Shareholder note receivable	Treasury stock	Accumulated other comprehensive income (loss)	Accumulated deficit
Balance at Dec. 31, 2017	$ (26,658)				$ 2		$ 436,803		$ (5,000)	$ (97)	$ 1,093	$ (459,459)
Balance, shares at Dec. 31, 2017			5,000		19,857,000
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Stock-based compensation	812						812
Issuance of Series B preferred stock, net of offering costs of $2.6 million	42,823						42,823
Issuance of Series B preferred stock, net of offering costs, shares				45,000
Common stock issued for conversion of Series A preferred stock, shares			(1,000)		637,000
Common stock issued for vesting of restricted stock awards, net of shares repurchased for tax liability, shares					38,000
Common stock issued for warrant exercises	4,128						4,128
Common stock issued for warrant exercises, shares					2,061,000
Issuance of common stock and warrants for the acquisition of SafeOp		$ 11,468						$ 11,468
Issuance of common stock and warrants for the acquisition of SafeOp, shares						$ 2,975
Prepaid forward contract for the additional shares to be issued for the acquisition of SafeOp		938						938
Foreign currency translation adjustments	(22)										(22)
Net loss	(1,916)											(1,916)
Balance at Mar. 31, 2018	31,573				$ 2		496,972		(5,000)	(97)	1,071	(461,375)
Balance, shares at Mar. 31, 2018			4,000	45,000	25,568,000
Balance at Dec. 31, 2017	(26,658)				$ 2		436,803		(5,000)	(97)	1,093	(459,459)
Balance, shares at Dec. 31, 2017			5,000		19,857,000
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of common stock for acquisition of SafeOp - Milestone 2, shares						443,421
Balance at Dec. 31, 2018	17,574				$ 4		523,525		(5,000)	(97)	1,064	(501,922)
Balance, shares at Dec. 31, 2018			4,000		43,368,000
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Stock-based compensation	1,565						1,565
Distributor equity incentives	42						42
Distributor equity incentives, shares					15,000
Common stock issued for conversion of Series A preferred stock, shares			(4,000)		1,858,000
Recognition of beneficial conversion feature -SafeOp Convertible Notes	242						242
Common stock issued for stock option exercises	14						14
Common stock issued for stock option exercises, shares					8,000
Common stock issued for vesting of restricted stock awards, net of shares repurchased for tax liability	(183)						(183)
Common stock issued for vesting of restricted stock awards, net of shares repurchased for tax liability, shares					442,000
Issuance of common stock for acquisition of SafeOp - Milestone 2 | Milestone 2		$ 2,889						$ 2,889
Issuance of common stock for acquisition of SafeOp - Milestone 2, shares | Milestone 2						887,000
Issuance of common stock for acquisition of SafeOp - Milestone 2, shares						886,843
Foreign currency translation adjustments	75										75
Net loss	(12,968)											(12,968)
Balance at Mar. 31, 2019	$ 9,250				$ 4		$ 528,094		$ (5,000)	$ (97)	$ 1,139	$ (514,890)
Balance, shares at Mar. 31, 2019					46,578,000