Comparison of Bone Tunnel Widening after ACL Reconstruction between Bioabsorbable Interference Screw and Metallic Interference Screw Fixation

ABSTRACT

PURPOSE: We evaluated the relationship among the radiographic enlargement of femoral and tibial bone tunnels, fixation material, clinical results and period of follow-up after anterior cruciate ligament(ACL) reconstruction with single incision arthroscopic technique using bone-patella tendon-bone. MATERIALS AND METHODS: We evaluated 91 knees of arthroscopic ACL reconstruction during the period of June 1993 to February 2001 excluding combined posterior cruciate ligament(PCL) injury. Average follow-up period was 44 months(12-78 months). We classified these cases into bioabsorbable screw group and metal screw group according to the screw materials. We took anteroposterior and lateral X-ray films at postoperative 3 months, 1 year, final follow up and measured the size of femoral and tibial tunnel. We evaluated the side-to-side difference using KT-2000 arthrometer and clinical results with Lysholm score. RESULTS: Eight cases of 47 cases in bioabsorbable screw group had bony cystic changes at femoral tunnel and 44 cases in metal screw group had not. Tibial tunnel widening was seen in 38 cases of absorbable screw group and 31 cases of metal screw group. Cases which had femoral and tibial tunnel widening had no knee joint instability clinically. CONCLUSION: There were femoral tunnel widening in bioabsorbable screw group, but not in metal screw group. Delayed inflammatory reaction in bioabsorbable screw may make this phenomenon but there was no correlation between femoral tunnel widening and clinical results. More longterm follow-up will be needed for futher degenerative changes and graft failure.