Evaluation of the Prognostic Value of Biological Markers, Coll2-1 and Coll2-1NO2 in Patients With Symptomatic Knee Osteoarthritis

Inclusion Criteria: * Male or female, aged 45 to 80 years with a BMI ≤ 40 * With an uni- or bilateral femorotibial knee osteoarthritis associated or not with a femoro-patellar knee osteoarthritis * Responding to clinical and radiological criteria of the ACR * Symptomatic for more than 6 months (for the most painful knee) * K\&L radiological grade of Felson II or III * With a cartilage lesion identified during MRI and either at least 1 out of 4 MRI severity criteria: * bone oedema * meniscal lesion in the central region of the medial compartment * effusion without answer to corticosteroids * zone without cartilage * or at least 1 out of 3 clinical severity criteria: * genu varum\>3° * previous meniscal surgery * known polyarthritis * effusion on the target knee * Sign an informed consent after being informed * Able to follow the instructions of the study * With an agreement from the physicians having established the diagnosis of osteoarthritis (if any) to give relevant information to the investigator * With health insurance (for France). Exclusion Criteria: For osteoarthritis: * Isolated patellofemoral arthritis * Chondromatosis or villo-nodular synovioma of the knee * Recent trauma-induced knee pain * Joint disease due to joint dysplasia, aseptic osteonecrosis, acromegaly, Paget's disease, hemophilia, hemochromatosis, … * inflammatory pathologies as rheumatoid polyarthritis, gout arthritis, infectious arthritis * Diseases that may interfere with the evaluation of osteoarthritis (radiculalgia of lower limbs, arteritis, …) * Genu valgum (degree considered as pathological by the physician) For previous treatments: • Treatment with strontium ranelate, bisphosphonates, SERM and PTH For known associated diseases: * Serious associated diseases: severe liver or renal failure, uncontrolled cardiovascular disease, HIV, hepatitis B or C * Knee tumor For patients: * Patient who participated to a therapeutic clinical trial 3 months before the T0 inclusion visit * Patient who are the subject of a judicial protection measure or under guardianship * Pregnant woman For MRI contraindications: * Patient with a pacemaker, an implantable defibrillator, neurosurgical clips, a neurostimulator, cochlear implant, a stent, an insulin pump * Patient with a ferromagnetic splinter in the body, or having wire sutures * Serious mobility problem (Parkinson, tremors)