Differences in Outcomes and Failure Rates Between Allografts and Autografts in Revision Anterior Cruciate Ligament Reconstruction

Anterior cruciate ligament (ACL) rupture is one of the most common knee injuries, particularly in young and physically active individuals. Despite advances in reconstruction techniques, graft failure and rerupture remain clinically relevant. Revision ACL surgery is more complex than primary reconstruction and is associated with inferior outcomes, with rerupture rates of approximately 13%, reaching up to 25% when both subjective and objective failure criteria are considered. The main goal of ACL reconstruction is to restore anteroposterior and rotational knee stability, prevent secondary meniscal and cartilage damage, and enable return to sport. Surgical outcomes depend on several intraoperative factors, including graft choice and tunnel geometry, which are particularly relevant in revision settings. Diagnosis of ACL rerupture is primarily clinical, based on instability tests (Lachman, anterior drawer, pivot shift), and supported by instrumental assessment such as the KT-1000 arthrometer, which provides an objective measure of joint laxity. Revision ACL reconstruction can be performed using different surgical techniques (single-bundle, double-bundle, or combined extra-articular procedures) and graft types (autograft or allograft). Surgical strategy depends on multiple factors such as meniscal and cartilage status, previous surgery characteristics, tunnel positioning/enlargement, and fixation devices. However, no consensus exists regarding the optimal approach in terms of mid- to long-term outcomes. A major long-term complication is the development of osteoarthritis, particularly in this typically young and active patient population. Identification of modifiable factors, such as surgical technique and graft type, may help reduce failure risk and joint degeneration. This study aims to evaluate clinical and radiographic outcomes over a follow-up period exceeding two years in patients undergoing revision ACL reconstruction with different surgical techniques and graft types. The study also integrates objective knee laxity assessment using KT-1000 and markerless motion analysis based on artificial intelligence. Functional movements are recorded via video and analyzed using Sports2D software, enabling 2D kinematic analysis without markers or sensors, providing quantitative functional data to complement clinical and radiographic evaluation.