Bilok Interference Screws for Anterior Cruciate Ligament Reconstruction: Clinical and Radiographic Outcomes

Purpose: The purpose of this study was to evaluate the clinical effectiveness and radiographic response of a poly-L-lactide (PLLA)/β–tricalcium phosphate (TCP) interference screw for anterior cruciate ligament (ACL) reconstruction. Methods: In a consecutive series of patellar tendon autograft ACL reconstructions, all patients had both ends fixed with PLLA/β-TCP screws. Inclusion criteria were positive Lachman and pivot-shift tests and closed or nearly closed growth plates. Exclusionary criteria were posterior cruciate ligament tears and bilateral ACL or multiple ligament injuries. Tegner, Lysholm, Cincinnati, and International Knee Documentation Committee activity scores; Lachman and pivot-shift data; radiographic examinations; and KT measurements (MEDmetric, San Diego, CA) were obtained. Results: In this study 41 patients met the criteria (31 male and 10 female patients), at a mean follow-up of 34 months (range, 24 to 44 months). Of these patients, 40 were available for follow-up (1 had died). Postoperatively, the mean Cincinnati score was 83 (64 preoperatively), the mean Tegner score was 5.5 (3.2 preoperatively), the mean Lysholm score was 88 (59 preoperatively), and the mean International Knee Documentation Committee activity score was 3.0 out of 4 (1.8 preoperatively). No patients had positive postoperative Lachman or pivot-shift tests. The maximum difference based on KT manual examinations 3 mm or less. Adverse events included screw breakage during insertion. Postoperative radiographs showed rapid bone plug incorporation. Radiographic tunnel obliteration with bony ingrowth was shown at 2 and 3 years’ follow-up. Conclusions: The PLLA/β-TCP interference screw performed well clinically based on both subjective and objective results. Radiographic screw incorporation into the adjacent bone was apparent at 3 years. Level of Evidence: Level IV, therapeutic case series.