[The non-traumatic femur head necrosis in the adult. I: pathophysiology, clinical picture and therapeutic options].

Intraosseous vascularization is the common pathway of the multifactorial causes of avascular necrosis of the hip (AVN). Recurring ischemic phases could lead to bone necrosis in the initial stage of the disease, when it is still reversible. A spontaneous repair mechanism can lead to complete healing at this stage. The necrotic area demarcates the superior-anterior aspect from the residual femoral head with a reactive interface in the irreversible early stage of the disease. In this stage damage to the femoral head can only be delayed with core decompression or femoral osteotomy, because a sufficient repair mechanism is no longer possible. When the articular surface collapses the early stage gives way to the late stage. Cartilage incongruence and microfracture lead to progressive destruction of the femoral head and to secondary osteoarthritis. In this late stage femoral osteotomy is only successful in carefully selected patients. Total hip replacement is the last resort for patients with painful destruction of the joint. As clinical symptoms are unspecific, MRI plays an important role for early diagnosis of AVN in the initial or early stages. Conservative treatment is not successful in any of the three stages of the disease.