Influence of the Different Types of Tibial Fixation in the Reconstruction of the Anterior Cruciate Ligament of the Knee: Osseous Integration, Ligament Maturation and Clinical Results.

Influence of different tibial fixation methods in anterior cruciate ligament (ACL) reconstruction: bone integration, graft maturation, and clinical outcomes. Primary Objective To assess whether any of the four tibial fixation techniques is superior in terms of: Graft-bone integration (CT/MRI), Graft maturation (MRI), Clinical outcomes (IKDC, Lysholm, Tegner scores; manual and instrumented knee stability with KT-1000 arthrometer). Secondary Objectives Compare clinical outcomes among groups (IKDC, Lysholm, Tegner). Compare re-rupture rates and patient satisfaction. Study Design Prospective randomized trial. The study will be registered in the international Clinical Trials registry. Inclusion Criteria Age ≥18 years. Complete ACL rupture treated with arthroscopic ACL reconstruction using autologous hamstring tendons. Exclusion Criteria Age ≥55 years. Patients treated with allografts, bone-patellar tendon-bone grafts, or quadriceps tendon grafts. Malpositioned tunnels (evaluated by MRI at 6 months postop). Previous knee surgery. Femoral or tibial deformities. Multiligament injuries. Note: Soft tissue procedures (e.g., meniscal repair) are not exclusion criteria. Randomization Patients meeting inclusion/exclusion criteria will be randomized (via Research Randomizer: https://www.randomizer.org/ ) into 3 groups: Group A (TORN): bioabsorbable interference screw, same diameter as the tunnel. Group B (TORN+1): bioabsorbable interference screw, one mm larger than the tunnel diameter. Group C (TORN-BT): interference screw (same size as tunnel) + second fixation with cortical button/plate. Sample size: 37 patients per group, 111 total. Follow-up Radiographic, CT, and MRI evaluation pre-op, at 15 days, and at 1 year post-op. Clinical and radiological follow-up for 1 year. Statistical Analysis In the prospective phase, Student's t-test will be performed for comparison of pre- and postoperative variables. All variables will also be compared between