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

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

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)

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.

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

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

This is a clinical examination maneuver used to assess rotational instability of the knee. The test is performed by applying a valgus and internal rotation stress during knee flexion; the occurrence of a tibial "shift" or "clunk" suggests a lesion of the reconstructed ACL (neo-ACL) associated with rotational instability. It is graded on a scale from 0 to 3.

The Tegner Score is a physical activity rating scale that measures the level of participation in occupational and sports activities. The score ranges from 0 to 10, where:

0 indicates inability to work or severe disability due to knee problems;

10 indicates participation in competitive sports at national or international level (e.g., professional football).

Intermediate levels describe progressively more demanding physical activities, distinguishing between activities of daily living, light or heavy work, and recreational or competitive sports.

The Tegner Score is frequently used in combination with other instruments (such as the IKDC or Lysholm scores) to define the patient's functional level before injury and after treatment. In the context of this study, the score is collected through a direct patient interview conducted by the investigator.

The WOMAC (Western Ontario and McMaster Universities Osteoarthritis Index) is a self-administered questionnaire specifically developed to assess patients with hip and knee osteoarthritis. The instrument evaluates the impact of the disease on pain, stiffness, and physical function.

The questionnaire consists of 24 items divided into three main domains:

• Pain (5 items)
• Joint stiffness (2 items)
• Physical function (17 items)

The total score is normalized on a 0-100 scale.

The KT-1000 is an objective assessment device that measures anterior tibial translation relative to the femur by applying a predefined force to translate the tibia anteriorly. Its use is part of routine clinical practice in the outpatient setting of the Second Orthopaedic and Trauma Clinic of the IOR and aims to quantitatively assess static anteroposterior knee laxity following anterior cruciate ligament reconstruction. The unit of measurement is millimetres

Knee function will be assessed during functional tasks (walking, lunges, squat) using a markerless AI-based video analysis system (Sports2D). The software estimates 2D joint kinematics (hip, knee, ankle, trunk) from videos recorded in frontal and sagittal planes without the use of sensors or markers. The system is non-invasive, already used in clinical practice, and installed locally to ensure data protection.

Videos are processed through an internal MATLAB script that extracts kinematic outputs (.mot and .trc files) using automated AI-based analysis. Data are anonymized via alphanumeric IDs, and videos are deleted after processing to minimize data retention.