Study Comparing Two Methods for the Treatment of Large Chondral and Osteochondral Defects of the Knee

Inclusion Criteria: * Patients aged between 15-50 years * Symptomatic chondral and osteochondral defect, grade III and IV according to the ICRS classification, and size between 2.5 and 15 cm2 * Failure of a conservative treatment * Patient in good general condition, documented by an ASA score ≤ 2 (American Society of Anesthesiologists) * Patient considered compliant and able to participate in rehabilitation and pre- and post-operative follow-up * Consent to participate in the study Exclusion Criteria: * All inflammatory and synovial pathologies * Diffuse or mirror lesions * An unfavorable biomechanical environment * Obesity grade II or higher, with a BMI\>35 kg/m2 * Active smoking/ active drug dependency (hard drugs) * Poor compliance * The patient is already part of another clinical trial that may compromise the present study * Vulnerable populations (except minors aged 15-18 years) * Presence of open growth plate (15-18 years) * Pregnancy or planned pregnancy during the study (MRI-related contra-indication) * Proven allergy to penicillin and gentamicin (for MACT group) and porcine collagen (for both groups) For final inclusion, an additional exclusion criteria will be assessed after randomization: \- Positive to HIV, HBV, HCV, syphilis.