Note 15 - Revenue by Product Group, by Significant Customer and by Geographic Region; Geographic Information - Product Revenue by Product Group (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Product Revenue	$ 28,884	$ 27,178	$ 28,340	$ 23,381	$ 28,296	$ 25,783	$ 26,575	$ 22,278	$ 107,783	$ 102,932	$ 87,696
Concentration risk, percentage									100.00%	100.00%	100.00%
Orthobiologics [Member]
Product Revenue									$ 93,816	$ 89,695	$ 73,247
Concentration risk, percentage									87.00%	87.00%	84.00%
Dermal [Member]
Product Revenue									$ 2,755	$ 2,759	$ 2,266
Concentration risk, percentage									3.00%	3.00%	2.00%
Surgical [Member]
Product Revenue									$ 5,262	$ 5,427	$ 5,812
Concentration risk, percentage									5.00%	5.00%	7.00%
Other [Member]
Product Revenue									$ 5,950	$ 5,051	$ 6,371
Concentration risk, percentage									5.00%	5.00%	7.00%