The aim of the project is to assemble and to follow on a 10-year period a nationwide representative sample of lower limb OA patients.

General objectives: To document the natural history and to identify predictive factors of the evolution and consequences of hip and knee OA in terms of pain, functional disability, structural damage, quality of life, autonomy, medical and health care use and cost of disease.

Inclusion Criteria:

• male and female aged between 40 and 75 years
• symptomatic hip or knee, uni or bilateral OA with clinical diagnosis confirmed by a medical physician and satisfying ACR classification criteria
• Representative of prevalent cases in France at the cohort set-up time

Exclusion Criteria:

• presence of hip or knee joint replacement surgery
• comorbidities severe enough to affect quality of life significantly or likely to induce a high health care consumption independently of OA
• an history of osteotomy
• Patello-femoral osteoarthritis without tibio-femoral osteoarthritis
• Other joint diseases of the target joints
• adult under legal protection or not able to consent