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)