Evaluation of Mobility in Subjects With Severe Knee Osteoarthritis Who Are to Undergo Total Knee Replacement

Inclusion Criteria: * Patient over 60 years old * Presence of unilateral knee osteoarthritis (Kellgren and Lawrence radiographic stage ≥ 3) in the femorotibial compartment and/or Iwano stage ≥2 in the femoropatellar compartment); * Average VAS (Visual Analogic Scale) pain on a reference joint (knee) \> 40/100 during the past month. * Indication for prosthetic knee surgery (total knee replacement) * Failure of a well-conducted medical treatment (at least one prior infiltration with corticoids or hyaluronic acid or PRP (Platelet-rich plasma)) Exclusion Criteria: * Presence of an inflammatory joint disease (rheumatoid arthritis, spondyloarthritis, microcrystalline pathology) * Presence of a post-traumatic gonarthrosis * Frontal deformity of the lower limb \> 15 * Preoperative flessum \> 15° or preoperative knee mobility \< 90° * Neurological pathology * Spinal pathology that is painful or causes deformity (severe Cobb scoliosis \> 20°) * History of trauma or surgery of the lower limbs in the last two years, * Presence of at least one lower limb prosthesis (total hip or ankle prosthesis) * Subject with a contraindication to MRI examination (pacemaker, neurosensory stimulators, cardiac defibrillator, cochlear implants, ferromagnetic ocular or cerebral foreign bodies...) * Subjects with a contraindication to DXA examination (coronary stent or metallic cardiac sutures, pacemaker or automatic defibrillator, obesity with a BMI \> 35kg/m2, insulin pump, weight over 200kgs) * Subject with a legal protection measure (guardianship, curatorship) * Subject under legal protection * Subject not affiliated to a social security system or not benefiting from such a system * Absence of informed written consent