ACL tear is a pathology of the knee quite common in athletes mainly caused by a twisting movement. The diagnosis of ACL tear can be confirmed by MRI (magnetic resonance imaging). This method makes it possible to visualize the inside of the knee and to diagnose lesions associated with rupture of the ACL (in particular meniscal lesions).

Obtaining a 3D model of patients' joints from a imaging is of growing interest to plan the gesture in preoperative but also to evaluate this gesture postoperatively. In orthopedic surgery, the baseline preoperative imaging is MRI. However, 3D models are generally obtained from a scanner-like imaging.

In this context, obtaining a 3D model from MRI imaging would make it possible to have a model that fits into the care pathway patients, without subjecting them to irradiation and visualizing anatomical structures not visible on CT.

However, the geometric precision and the reproducibility of the 3D reconstructions of joints reconstructed from an MRI remains unknown and must be evaluated to consider their clinical use.

Rupture of the anterior cruciate ligament (ACL) is a pathology of the knee quite common in athletes. The main cause of an ACL tear is, in the majority of cases, an indirect trauma, caused by a twisting movement (example: the foot remains blocked on the ground while the knee rotates in or out).

Sometimes the clinical examination of the ACL tear may not be conclusive.This is usually the case when the patient's knee swelling is too large and that clinical tests are then difficult to carry out. The diagnosis of ACL tear can therefore be confirmed by MRI (magnetic resonance imaging). This method makes it possible to visualize the inside of the knee. In addition, the realization of the MRI will also help to diagnose lesions associated with rupture of the ACL and in particular meniscal lesions. This exam has become indispensable and is carried out in the vast majority of cases.

Obtaining a 3D model of patients' joints from a imaging is of growing interest. These 3D models allow particular to plan the gesture in preoperative but also to evaluate this gesture postoperatively. In orthopedic surgery, for patients suffering from an ACL tear, the baseline preoperative imaging is MRI. However, 3D models are generally obtained from a scanner-like imaging. This imagery has the advantage of presenting a very good definition of bone tissue but it is not part, for a large number of patients, routine preoperative imaging. It is irradiating and does not allow easy highlighting of other structures such as cartilage or menisci.

In this context, obtaining a 3D model from MRI imaging would make it possible to have a model that fits into the care pathway patients, without subjecting them to irradiation and visualizing anatomical structures not visible on CT.

However, the geometric precision and the reproducibility of the 3D reconstructions of joints reconstructed from an MRI remains unknown and must be evaluated to consider their clinical use. This is the purpose of this research.

Inclusion Criteria:

• Patient, male or female, aged between ≥ 18 and ≤ 45 years old
• Patient eligible for ACL reconstruction
• Patient with an MRI performed at the SANTY orthopedic center or according to the protocol defined by the radiologists of the orthopedic center SANTY
• Patient with an MRI performed ≥ 3 weeks after ACL tear
• Affiliated patient or beneficiary of a social security scheme
• French-speaking patient who signed an informed consent

Exclusion Criteria:

• Patient with a surgical history on the affected knee
• Patient with a multi-ligament lesion
• Patient already included in another study
• Protected patient: adult under guardianship, curatorship or other protection legal, deprived of liberty by judicial or administrative decision
• Patient hospitalized without consent