This study hypothesizes that the tunnel positioning and drilling direction in two single-bundle reconstruction techniques (Anatomical Single-Bundle Reconstruction, ASBR, and Central Axial Single-Bundle Reconstruction, CASBR) influence the biomechanical environment of the graft, thereby affecting graft remodeling and maturation, ultimately impacting postoperative outcomes. Studies have shown that the graft bending angle (GBA) is a critical factor affecting graft ligamentization. ASBR, with a higher GBA, may result in poorer graft maturation, while CASBR, with a lower GBA, may provide a more favorable biomechanical environment. Additionally, graft volume has been identified as an important factor influencing postoperative graft maturation. Therefore, this study also examines the double-bundle reconstruction (DBR) technique, which has a GBA similar to CASBR. The Impact of Three Techniques on Graft Maturation Anatomical Single-Bundle Reconstruction (ASBR) ASBR involves drilling a single tunnel at both the femoral and tibial ends, with the tunnel positioned at the center of the dense fiber area of the ACL footprint. The femoral tunnel is positioned at 90° knee flexion and drilled at 120°, while the tibial tunnel is positioned at 70° knee flexion. Due to the higher GBA in ASBR, the graft may experience greater bending stress during motion, leading to impaired graft maturation, limited ligamentization, and increased stress concentration around the tunnel, potentially causing tunnel widening. Central Axial Single-Bundle Reconstruction (CASBR) CASBR also involves drilling a single tunnel at both ends, but the tunnel is positioned in the posterior region of the dense fiber area of the ACL footprint, mimicking the central axis of the native ACL. The femoral tunnel is positioned at 90° knee flexion and drilled at 120°, while the tibial tunnel is positioned at 70° knee flexion. Compared to ASBR, CASBR's lower GBA results in more uniform graft stress distribution, promoting better graft maturation and reducing the risk of stress concentration and tunnel widening. Double-Bundle Reconstruction (DBR) DBR involves drilling two tunnels at both the femoral and tibial ends, targeting the dense fiber areas of the anterior medial bundle (AMB) and posterior lateral bundle (PLB) of the ACL footprint. The positioning of the PLB tunnel is similar to CASBR, while the AMB tunnel is located in the anterior region of the footprint. DBR provides a more anatomically accurate distribution of forces, leading to a more even biomechanical environment. However, the increased number of tunnels may complicate stress distribution. Impact on Postoperative Outcomes ASBR, with its higher GBA, may lead to poor graft maturation and increased tunnel widening. CASBR, with a lower GBA, offers a more favorable biomechanical environment for graft maturation. While DBR ensures a more uniform force distribution, the additional tunnels may introduce complexities in stress distribution, potentially affecting postoperative recovery and return to sports (RTS).
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tunnel widening
Timeframe: From two days postoperatively to two years postoperatively