Accrued expenses (Details) (USD $)
Dec. 31, 2014
Dec. 31, 2013
Customer deposits $ 2,516,202 $ 1,795,803
Accrued compensation and benefits 984,227 795,584
Other payables 379,019 242,993
Accrued interest 1,025,623 2,250
Due to Arthrex 324,531 1,630,564
Accrued professional fees 285,446 199,634
Accrued loss on abandonment of lease, current portion 103,176 0
Accrued Angel machine refurbishment costs 600,000 0
Accrued Liabilities, Current $ 6,218,224 $ 4,666,828