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

Abstract

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. Multicentered prospective randomized study. 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. 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. 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 II, therapeutic.