Business segment information - Schedule of External Net Sales for Continuing Operations by GBU (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended	9 Months Ended
Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2012	Sep. 30, 2011
Segment Reporting Information [Line Items]
Reported Growth (as a percent)	(2.00%)		1.00%
Constant Currency Growth (as a percent)	1.00%		3.00%
Total Net Sales	$ 114,752	$ 117,306	$ 350,286	$ 347,036
Spine Repair Implants and Regenerative Biologics [Member]
Segment Reporting Information [Line Items]
Reported Growth (as a percent)			3.00%
Constant Currency Growth (as a percent)			3.00%
Total Net Sales	36,634	36,769	110,892	107,608
Spine Regenerative Stimulation [Member]
Segment Reporting Information [Line Items]
Reported Growth (as a percent)	8.00%		6.00%
Constant Currency Growth (as a percent)	8.00%		6.00%
Total Net Sales	42,759	39,734	125,325	118,012
Spine [Member]
Segment Reporting Information [Line Items]
Reported Growth (as a percent)	4.00%		5.00%
Constant Currency Growth (as a percent)	4.00%		5.00%
Total Net Sales	79,393	76,503	236,217	225,620
Orthopedics [Member]
Segment Reporting Information [Line Items]
Reported Growth (as a percent)	(13.00%)		(6.00%)
Constant Currency Growth (as a percent)	(4.00%)		1.00%
Total Net Sales	$ 35,359	$ 40,803	$ 114,069	$ 121,416