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.
Age 18-50 years at the time of surgery
Male and female patients
Patients undergoing revision anterior cruciate ligament (ACL) reconstruction with possible associated procedures, with at least 2 years of follow-up
Written informed consent to participate in the study
Patients lost to follow-up
Refusal to provide informed consent
Advanced knee osteoarthritis (Outerbridge grade III-IV) at the time of surgery
Severe obesity (BMI > 35)
Patients will be recruited among all subjects who underwent revision anterior cruciate ligament reconstruction at the SC Orthopaedic and Trauma Clinic II of the Istituto Ortopedico Rizzoli, with at least 2 years between the surgical procedure and the clinical-radiological reassessment proposed in this study, from 01/01/2016 to 31/12/2024 at the Istituto Ortopedico Rizzoli. Such reassessment is part of routine clinical practice.
Cohort
Retrospective
Not listed
Survival rate
Failures will be recorded and documented in the case report form (CRF), during telephone questionnaires, and through the patient's clinical records (Electronic Health Record, SIR 2020, and hospital databases). The survival rate at follow-up will then be estimated using a Kaplan-Meier survival curve
Lysholm Knee Score
It is a validated measurement scale that assesses knee function through 8 items, allowing evaluation of knee condition in relation to the functional demands of activities of daily living. This assessment form is used to evaluate surgical outcomes in patients undergoing surgery for ligamentous or meniscal knee injuries. The final score is obtained by summing the scores of the individual items and ranges from 0 to 100. Scores are categorized into subgroups as follows: Excellent (95-100); Good (84-94); Fair (65-83); Poor (\<64)
International Knee Documentation Committee - Objective Knee Evaluation Form
The objective IKDC is a clinical assessment form completed by the investigator, which allows standardized classification of knee status through objective parameters. The evaluation is based on four main domains: joint effusion, range of motion, ligament stability (in particular Lachman test, pivot-shift test, and anterior/posterior drawer tests), and joint compartments (meniscal and ligament examination). The final outcome is not expressed as a continuous numerical score, but rather as a classification into four categories: A (Normal) B (Nearly normal) C (Abnormal) D (Severely abnormal) The final classification corresponds to the worst score obtained among the evaluated domains.
Anterior drawer test
It allows assessment of anterior tibial translation relative to the femur with the knee flexed at 90 degrees. An increased translation suggests a lesion of the reconstructed ACL (neo-ACL). It is graded on a scale from 0 to 3
Lachman test
It allows assessment of anterior tibial translation relative to the femur with the knee flexed at 30 degrees. Increased translation suggests a lesion of the reconstructed ACL (neo-ACL). It is graded on a scale from 0 to 3
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Stefano Zaffagnini
Lead sponsor
Istituto Ortopedico Rizzoli
Sponsor institution
