Comparison of Femoral and Tibial Tunnel Widening after Anterior Cruciate Ligament Reconstruction with Biostable and Bioabsorbable Interference Screws: A Radiographic Evaluation

Abstract

Objective and Background: Tunnel widening is a common occurrence following ACL reconstruction, with the exact cause still not fully understood. One factor that may contribute is the choice of graft fixation device. This study aims to compare tibial and femoral tunnel widening after arthroscopic ACL reconstruction, using biostable versus bioabsorbable interference screws, as seen on radiographs. Methods: This randomized prospective study involved ACL reconstruction with a single-bundle hamstring graft and femoral fixation using an endobutton. Tibial fixation was performed using either a biostable screw (Group 1) or a bioabsorbable screw (Group 2). Tunnel widening was measured on AP and lateral radiographs at postoperative, six months, and one year intervals. Statistical analysis was performed using the Chi-square test and the Mann-Whitney test to compare tunnel widening between groups. Results: There were no statistically significant differences in tunnel widening at the postoperative period, six months, or one year within each group. However, a significant difference was found between the biostable and bioabsorbable screw groups, particularly at the one-year follow-up. This difference was evident in both the femoral and tibial tunnels on AP and lateral radiographs, with all comparisons showing a p-value < 0.05. Conclusion: The study found significant differences in tunnel widening between the two screw types, especially at the one-year follow-up. These results suggest that the choice of fixation device may influence tunnel widening over the long term, though no differences were observed in the short-term (postoperative and six months).