Initial fixation strength of polylactic acid interference screws in anterior cruciate ligament reconstruction

The initial fixation properties of bioresorbable polylactic acid (PLA) interference screws designed for anterior cruciate ligament reconstruction were evaluated using an in vitro bovine model. The surgical technique of interference screw fixation of the bone-patellar tendon-bone autograft complex performed clinically was reproduced in an adult bovine model. The reconstructed knee was tested oriented in 30 degrees of flexion to allow examination of the femoral and tibial fixation properties simultaneously. This model examined the initial fixation strength between PLA and metal interference screws as well as a partially degraded PLA implant. Data from this in vitro model indicate that PLA interference screws can provide similar initial fixation at both time 0 and after degradation for up to 28 days compared with metal interference screws for bone-tendon-bone ACL reconstructions.