OBJECTIVETo analyze the factors contributing to the failure of primary anterior cruciate ligament (ACL) reconstruction.

METHODSFrom November 2001 to July 2006, 13 patients underwent ACL reconstruction revision because of pathological instability in daily activities after primary ACL reconstruction, and the data of the patients were retrospectively analyzed.

RESULTSIn this group, 7 cases were reconstructed with bone-patellar tendon-bone (B-PT-B) autografts, 4 cases with hamstring tendon autograft and 2 cases with hamstring tendon allograft. There were malpositioned bone tunnels in 8 cases. Among them 4 cases had a femoral tunnel in the front of the predicted one, and in the other 4 cases, both the femoral and tibial tunnels were in the front of the predicted ones. In 2 cases reconstructed with allograft, one had to receive a twice operation to take out the allograft because of serious rejection, and the other claimed a failure because of the obviously enlarged bone tunnel. In the 2 cases reconstructed with B-PT-B autograft, malposition of the interference screw using to fasten the bone block had been founded in the upper bone tunnel. One case suffered from postoperative infection and had been cured by the anti-biotic treatment after arthroscopic debridement. Then the reconstructed ACL in 7 cases had absolutely ruptured and been absorbed. Four cases had obviously loosen but still partly linked reconstructed ligament. Two cases had a malposited interference screw, and both of them had no fastening function. One case received the lytic operation due to knee stiffness. Two cases received primary bone transplantation and needed to receive a secondary revision operation owing to severe incompletion of spongy bone. The other 10 cases received primary revision. Among them 4 cases reconstructed with STG obtained from the same lateral, 4 cases reconstructed with STG obtained from the opposite lateral, 1 case reconstructed with B-PT-B obtained from the same lateral and 1 case reconstructed with iliotibiali tractus.

CONCLUSIONSThere are many reasons leading to failure of ACL reconstruction. Nevertheless, malposition of the bone tunnel, invalid fixation, rejection to allograft and other complications such as the enlargement of the bone tunnel, postoperative infection and adhesion are the major factors that predispose the primary construction to failure.