Note 4 - Acquisitions (Details Textual)				3 Months Ended
	Jun. 22, 2020 USD ($)	Oct. 11, 2019 USD ($)	Jul. 12, 2019 USD ($)	Mar. 31, 2021 USD ($)	Sep. 30, 2020 USD ($)	Dec. 31, 2020 USD ($)
Artegraft Inc [Member]
Payments to Acquire Businesses, Gross	$ 72,500,000
Escrow Deposit Disbursements Related to Property Acquisition	$ 7,500,000
Business Combination, Contingent Consideration, Liability, Total						$ 400,000
Business Acquisition, Purchase Price Allocation, Goodwill Expected Tax Deductible, Period (Year)	15 years
Acquired Finite-lived Intangible Assets, Weighted Average Useful Life (Year)	12 years 7 months 6 days
Artegraft Inc [Member] | First Earn-out [Member]
Business Combination, Contingent Consideration, Liability, Total	$ 5,800,000
Business Combination, Contingent Consideration, Unit Sales	20,000
Artegraft Inc [Member] | Second Earn-out [Member]
Business Combination, Contingent Consideration, Liability, Total	$ 5,800,000
Business Combination, Contingent Consideration, Unit Sales	24,000
Artegraft Inc [Member] | Third Earn-out [Member]
Business Combination, Contingent Consideration, Liability, Total	$ 5,800,000
Business Combination, Contingent Consideration, Unit Sales	28,800
Artegraft Inc [Member] | Catch-Up Payment [Member]
Business Combination, Contingent Consideration, Liability, Total	$ 400,000
Business Combination, Contingent Consideration, Minimum Unit Sales in Three Years	58,240
Business Combination, Contingent Consideration, Minimum Unit Sales in Three Years, Percent of Combined Individual Year Targets	80.00%
Business Combination, Contingent Consideration, Before Multiplied by Fraction	$ 17,500,000
Business Combination, Contingent Consideration, Denominator, Less Amount Paid	72,800
Artegraft Inc [Member] | Maximum [Member]
Business Combination, Consideration Transferred, Total	$ 90,000,000.0
CardioCel and VascuCel Biologic Patches [Member]
Payments to Acquire Businesses, Gross		$ 14,200,000
Business Combination, Contingent Consideration, Liability, Total		7,500,000		$ 2,000,000.0
Acquired Finite-lived Intangible Assets, Weighted Average Useful Life (Year)				10 years 4 months 24 days
Goodwill, Purchase Accounting Adjustments					$ (1,300,000)
CardioCel and VascuCel Biologic Patches [Member] | Technology Licenses [Member]
Business Combination, Consideration Transferred, Total		8,000,000.0
CardioCel and VascuCel Biologic Patches [Member] | Achieving Audited Financial Statements of Acquired Business [Member]
Payments to Acquire Businesses, Gross		300,000
CardioCel and VascuCel Biologic Patches [Member] | First Holdback [Member]
Business Combination, Contingent Consideration, Liability, Total		700,000
CardioCel and VascuCel Biologic Patches [Member] | Third Holdback [Member]
Business Combination, Contingent Consideration, Liability, Total		2,000,000.0
CardioCel and VascuCel Biologic Patches [Member] | Revenues Exceeding Twenty Million in the First Twelve Month Period After Closing Date [Member]
Business Combination, Contingent Consideration, Liability, Total		2,500,000
CardioCel and VascuCel Biologic Patches [Member] | Revenues Exceeding Fifteen Million in the First Twelve Month Period After Closing Date [Member]
Business Combination, Contingent Consideration, Liability, Total		1,200,000
CardioCel and VascuCel Biologic Patches [Member] | Revenues Exceeding Thirty Million in the Second Twelve Month Period After Closing Date [Member]
Business Combination, Contingent Consideration, Liability, Total		2,500,000
CardioCel and VascuCel Biologic Patches [Member] | Revenues Exceeding Twenty-Two and a Half Million in the First Twelve Month Period After Closing Date [Member]
Business Combination, Contingent Consideration, Liability, Total		1,200,000
CardioCel and VascuCel Biologic Patches [Member] | Extension of Product Shelf Life from 36 Months to 60 Months in the First Anniversary of Closing Date [Member]
Business Combination, Contingent Consideration, Liability, Total		500,000
CardioCel and VascuCel Biologic Patches [Member] | Maximum [Member] | Biological Patch Business Assets [Member]
Business Combination, Consideration Transferred, Total		$ 15,300,000
Tru-Incise Valve Cutter [Member]
Business Combination, Consideration Transferred, Total			$ 8,000,000.0
Payments to Acquire Businesses, Gross			$ 6,800,000
Acquired Finite-lived Intangible Assets, Weighted Average Useful Life (Year)			11 years 9 months 18 days
Business Combination, Deferred Purchase Consideration, Installment Payment			$ 400,000
Business Combination, Deferred Purchase Consideration			1,200,000
Acquisition Date Fair Value			$ 1,100,000
Business Combination ,Fair Value Inputs, Discount Rate			4.19%