Inclusion Criteria:

• Signed patient informed consent
• Symptomatic cartilage single lesion of the femoral condyle
• Lesion on femoral condyle between 1 and 5 cm²
• Agree to participate actively in a strict rehabilitation protocol and follow-up programme
• Agree to only use paracetamol mono-or combination preparation (max 4g/d) and NSAIDS during the study and to discontinue this medication 2 weeks before the baseline visit and the follow-up visits. The use of paracetamol mono-preparation (max 4g/d) is allowed up to one week before the baseline visit and the follow-up visits.
• Females of childbearing age should use a proven method to prevent pregnancy

Exclusion Criteria:

• Participation in concurrent trials
• Participation in previous trials within 3 months
• Subjects with hepatitis, HIV or syphilis
• Malignancy
• Alcohol or drug (medication) abuse
• Poor general health as judged by Investigator
• Clinically relevant second cartilage lesion on the patella
• Patellofemoral cartilage lesion
• Osteochondritis Dissecans (OCD) : recent OCD (within 1 year before baseline), depth of lesion > 0.5cm, subchondral slerosis
• Advanced osteoarthritis (OA) : radiographic atlas of OA grade 2-3
• Known allergy to gentamicin or penicillins (or presence of multiple severe allergies)
• Complex ligamentous instability of the knee
• Meniscal transplant
• Meniscal suture with meniscal arrows (ipsilateral)
• Meniscus resection : if < 1 yr before baseline - lateral meniscus resection or medial meniscus resection of more than 50%. If > 1 yr before baseline - ipsilateral meniscus resection of more than 50%, controlateral meniscus resection of more than 50% if ipsilateral meniscus is not intact, combination of medial and lateral meniscus resection and one of both > 50%.
• Varus or valgus malalignment of more than 5°
• Mosaicplasty (OATS)
• Microfracture performed less than 1 yr before baseline
• Having received hyaluronic acid intra-articular injections in the affected knee within the last 6 months of baseline
• Taking specific OA drugs such as chondroïtin sulfate, diacerein, n-glucosamine, piascledine, capsaicin within 2 weeks of the baseline visit
• Corticosteroïd treatment by systemic or intra-articular route within the last month of baseline or intramuscular or oral corticosteroïds within the last 2 weeks of baseline
• Chronic use of anticoagulants
• Uncontrolled diabetes
• Any concomitant painful or disabling disease of the spine,hips or lower limbs that would interfere with evaluation of the afflicted knee
• Any clinically significant or symptomatic vascular or neurologic disorder of the lower extremities
• Any evidence of the following diseases in the target joint : septic arthritis, inflammatory joint disease, gout, recurrent episodes of pseudogout, Paget's disease of bone, ochronosis, acromegaly, hemochromatosis, Wilson's disease, primary osteochondromatosis, heritable disorders, collagen gene mutation
• Current diagnosis of osteomyelitis
• Liver enzymes (SGOT, SGPT, Alkaline Phosphatase) of more then two times the upper limit of normal or any other result that is clinically important according to the Investigator
• CRP > 10 mg/l