Note 13 - Revenue by Product Group, by Significant Customer and by Geographic Location; Geographic Information - Product Revenue by Product Group (Details) - USD ($) $ in Thousands	3 Months Ended												12 Months Ended
	Dec. 31, 2020	[1]	Sep. 30, 2020	[2]	Jun. 30, 2020	[3]	Mar. 31, 2020	[4]	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Revenue	$ 32,688		$ 31,694		$ 30,678		$ 35,397		$ 29,772	$ 29,697	$ 30,418	$ 24,723	$ 130,457	$ 114,610	$ 105,555
Percentage of Revenue													100.00%	100.00%	100.00%
Joint Pain Management Therapies [Member]
Revenue													$ 83,029	$ 103,466	$ 96,719
Percentage of Revenue													64.00%	90.00%	92.00%
Joint Preservation and Restoration [Member]
Revenue													$ 39,368	$ 2,070	$ 1,127
Percentage of Revenue													30.00%	2.00%	1.00%
Manufactured Product, Other [Member]
Revenue													$ 8,060	$ 8,976	$ 7,685
Percentage of Revenue													6.00%	8.00%	7.00%
Product [Member]
Revenue													$ 130,457	$ 114,512	$ 105,531
Percentage of Revenue													100.00%	100.00%	100.00%

[1] In the quarter ended December 31, 2020, we recorded a pre-tax goodwill impairment charge of $24.4 million and we recognized a pre-tax benefit of $12.5 million related to a change in the fair value of our contingent consideration liability.

[2] In the quarter ended September 30, 2020, we recorded a pre-tax expense in the amount of $4.1 million related to a change in the fair value of our contingent consideration liability.

[3] In the quarter ended June 30, 2020, we recorded a pre-tax expense in the amount of $4.2 million related to a change in the fair value of our contingent consideration liability.

[4] In the quarter ended March 31, 2020, we recorded a pre-tax goodwill impairment charge of $18.1 million and we recognized a pre-tax benefit of $24.5 million related to a change in the fair value of our contingent consideration liability.