A prospective randomized comparison of bioabsorbable and titanium anterior cruciate ligament interference screws

Purpose:To compare the Phantom bioabsorbable polymer interference screw (DePuy, Warsaw, IN) with a titanium metal interference screw when used in fixation of femoral and tibial bone blocks in central third bone-patellar tendon-bone autograft anterior cruciate ligament (ACL) reconstructions. Type of study:Multicentered prospective randomized study. Methods:Two surgeons performed primary ACL reconstructions at different locations. Preoperatively, the patients were randomly assigned. One group received a titanium cannulated interference screw. The second group received the cannulated poly-L-lactic bioabsorbable Phantom screw. Data included subjective evaluation of activity level and International Knee Documentation Committee scores. Objective measures were made using the KT-1000 arthrometer (MedMetric, San Diego, CA), range of motion, presence of effusions, and complications intraoperatively or postoperatively. Measurements were made at 1 year and 2 years. Radiographic evaluation was carried out at least 2 years from the initial surgical date and interpreted by 2 independent orthopaedic surgeons. Results:At the 1-year follow-up (N = 97), pain was reported more during moderate activity in the Phantom screw group (6) compared with the titanium screw group (0) (P = .03). No statistical difference between range of motion (P = .45), activity level (P = .83), swelling with activity (P = .95), partial (P = .13) or full (P = .31) giving way, knee effusions (P = .33), or KT-1000 side-to-side difference (P = .53) were found. At the 2-year follow-up (N = 65), more subjects (18) in the Phantom interference screw group reported activity levels in the strenuous category compared with those in the titanium interference screws (7) group (P = .02). No differences were reported with respect to pain (P = .97), effusion (P = .17), partial (P = .28) or full (P = .27) giving way, swelling with activity (P = .21), range of motion (P = .64), or KT-1000 side-to-side difference (P = .96). Radiographic inspection showed no change in bone plug position, osteolysis, adverse effect, or complication caused by the bioabsorbable material. Some evidence of tunnel widening was seen in both groups. Conclusions:Use of a poly-L-lactic bioabsorbable interference screw can provide clinical results equal to that of a metal interference screw for fixation of a central third bone-patellar tendon-bone graft in ACL reconstruction. Level of evidence:Level II, therapeutic.