A Randomized Controlled Trial Comparing Chondro-Gide® to Microfracture Alone for Treatment of Knee Cartilage Defects.

Inclusion Criteria: * Male or female between 18 and 50 * One or two cartilage defects Grade III or IV according to Outerbridge classification * Defect size between 2 and 10 cm2 (inclusive) * Intact normal surrounding cartilage to suture the Chondro-Gide® membrane * Informed consent * Patient willing to fulfill a strict postoperative physiotherapy scheme Exclusion Criteria: * More than 2 defects * Defects on both knees * X-ray signs of osteoarthritis * Bone lesion \> 0.7 cm in the defect * Knee instability, varus or valgus deformation, status after complete meniscus resection, status after mosaicplasty, patella dysplasia * Rheumatoid, infectious disease * Skin lesion on the operated knee * Treatment with cartilage building medication * Drug and alcohol abuse * Chronic heart disease, endocrine or metabolic disease, Haemophilia A/B * Pregnancy or lactation * Collagen allergy * Participation in other Trials