[The aging of joints and osteo-arthrosis]

Although the frequency and severity of osteo-arthrosis regularly increase after the age of 50 years, individual's age does not seem to be a causal factor of this disorder. Indeed, osteoarthrosis does not affect all age individuals and not all joints are involved at the time. Various etiological factors (traumatisms, joint malformations and preexisting disorders, overuse of joints, etc.) are usually identified. Joint lesions in osteo-arthrosis are not those characteristic of senile involution, but rather represent proliferative reparative processes. Therefore, old age may act as one of the risk factors, which favors a development of osteo-arthrosis if others, more specific, etiological factors are present.