CONSOLIDATED STATEMENTS OF STOCKHOLDERS' EQUITY (DEFICIT) - USD ($) shares in Thousands, $ in Thousands	Total	SafeOp Surgical, Inc.	Series A 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 beginning, value at Dec. 31, 2016	$ (41,504)			$ 1		$ 419,787		$ (5,000)	$ (97)	$ 970	$ (457,165)
Balance beginning, shares at Dec. 31, 2016				9,049
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Stock-based compensation	3,902					3,902
Common and preferred stock and warrants issued in private placement, net of offering costs of $1.7 million	17,118			$ 1		17,117
Common and preferred stock and warrants issued in private placement, net of offering costs, shares			15	1,810
Issuance and conversion of preferred stock into common stock, net of offering costs, shares			(10)	4,964
Issuance of common stock for employee stock purchase plan	231					231
Issuance of common stock for employee stock purchase plan, shares				128
Shares issued for acquisition of intangible assets	473					473
Shares issued for acquisition of intangible assets, shares				285
Common stock issued for vesting of restricted stock awards, net of shares repurchased for tax liability, shares				183
Common stock issued for warrant exercises, net of issuance costs	3,337					3,337
Common stock issued for warrant exercises, shares				1,668
Warrant derivative liability reclassified to equity due to exercise of warrants	2,311					2,311
Issuance of common stock and warrants to board members	4,000					4,000
Issuance of common stock and warrants to board members, shares				1,770
Net change from reclassification of warrants to and from liability	(14,355)					(14,355)
Foreign currency translation adjustments	123									123
Net loss	(2,294)										(2,294)
Balance ending, value at Dec. 31, 2017	(26,658)			$ 2		436,803		(5,000)	(97)	1,093	(459,459)
Balance ending, shares at Dec. 31, 2017			5	19,857
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Stock-based compensation	5,649					5,649
Issuance of warrants in conjunction with Squadron Term Loan	1,708					1,708
Issuance and conversion of preferred stock into common stock, net of offering costs	42,610			$ 2		42,608
Issuance and conversion of preferred stock into common stock, net of offering costs, shares			(1)	14,986
Recognition of beneficial conversion feature - Series B Preferred Stock						13,488					(13,488)
Common stock issued for employee stock purchase plan and stock option exercises	666					666
Common stock issued for employee stock purchase plan and stock option exercises, shares				258
Common stock issued for vesting of restricted stock awards, net of shares repurchased for tax liability, shares				248
Common stock issued for warrant exercises, net of issuance costs	8,628					8,628
Common stock issued for warrant exercises, shares				4,311
Issuance of common stock and warrants for the acquisition of SafeOp | Milestone 1		$ 12,529					$ 12,529
Issuance of common stock and warrants for the acquisition of SafeOp, shares | Milestone 1					$ 3,265
Issuance of common stock for acquisition of SafeOp -Milestone 1 | Milestone 1		$ 1,446					$ 1,446
Issuance of common stock for acquisition of SafeOp - Milestone 1, shares | Milestone 1					443
Foreign currency translation adjustments	(29)									(29)
Net loss	(28,975)										(28,975)
Balance ending, value at Dec. 31, 2018	$ 17,574			$ 4		$ 523,525		$ (5,000)	$ (97)	$ 1,064	$ (501,922)
Balance ending, shares at Dec. 31, 2018			4	43,368