Absorbable and metal interference screws: comparison of graft security during healing

Anterior cruciate ligament replacement was performed on 71 sheep to compare graft security using a titanium or an absorbable polyglyconate interference screw (Acufex, Mansfield, MA) to hold the bone-patellar tendon-bone autograft. Early self mobilization was followed later by retrieval of most specimens up to 12 weeks. No grafts failed in vivo or migrated within the bone tunnel. Failure strengths of femur-graft-tibia preparations held by absorbable screws were lower initially but at no time were they statistically different to those held by metal screws. By 4 weeks, fibrous union between the graft tendon and tunnel wall led to no difference in failure strength if the screw was present or removed before measurement. Histologically, ossific incorporation of the graft bone was not evident until 6 weeks. A mild tissue reaction occurred around the absorbable screw. In the 2 12-month specimens, the polyglyconate had been largely replaced by fibrous tissue. Overall, the absorbable screw performed to a level comparable to the metal screw.