[Destructive arthrosis of the hip. Natural history, pathogenesis, and radiographic features]

Degenerative hip arthritis is caused by the joint failing to bear the normal walk load, because of changes in the anatomical components and of some factors leading to static or dynamic unbalance of the joint surfaces. Degenerative arthritis usually evolves slowly, but its evolution is rapid under certain circumstances and in elderly patients. In such cases destruction is severe and irregular erosions are observed in the femoral heads, which become small and move to the superior lateral edge of the acetabulum. Osteophytes and reactive osteosclerosis are uncommon. Severe pain, functional inability and lower limb shortening are quite constant findings. The patient is often immobilized in bed and risks his/her life. Since the pathogenesis of destructive arthritis is still debated and its clinical features are severe, the knowledge of the natural history and of the underlying factors appears to be very important. The only therapy is arthroprosthesis and prevention becomes, therefore, necessary. On the basis of radiographic findings, we selected three groups of elderly patients hospitalized from 1992 to 1995; of them, 178 had destructive arthritis. The control group consisted of 102 patients with degenerative arthritis and 188 with normal hip joints. The radiographic patterns were related to some clinical and laboratory findings, which are the suspected pathogenetic factors. Two main factors emerged, with high statistical development risk (p < 0.01): hypoxia from femoral head ischemia, due to atherosclerotic vasculopathy and associated anemia, and the articular biodynamic changes which, through minor repeated trauma, cause the lesions, with the appearance of stress fractures.