Biology and Clinical Experience of Absorbable Materials in ACL Fixation

Interference fixation for anterior cruciate ligament reconstruction is a common technique and can be used for patellar tendon and hamstring autografts and allografts. Bioabsorbable materials offer several advantages over metal interference screws. This study examines the in vivo histology of one biodegradable interference screw (PLLA) and reports the long-term clinical outcome of the same screw in a randomized, prospective study. The histology was investigated in a series of adult sheep undergoing patellar tendon autografts secured by either Bioscrew (PLLA) or metal interference screws. Nineteen sheep were radiologically and histologically assessed at intervals up to nearly 4 years. In the human clinical trial, a prospective randomized study was conducted of patellar tendon autografts also secured by either Bioscrew or metal interference screws. With an average follow up of 35 months (range, 24–65 months), Lachman's, pivot shift, Lysholm, Tegner, KT, motion, and radiographic evaluations were made. None of these variables showed a statistically significant difference between groups. No radiographic evidence of lytic change or bone resorption around the Bioscrews was observed in either human or sheep studies. No complications related to the bioabsorbable material (PLLA) occurred. We conclude that the Bioscrew is comparable to metal screw fixation and is safe and effective for interference graft fixation.