[Aseptic necrosis of the femoral head in young adults].

Aseptic necrosis of the femoral head is a well-defined entity. The underlying diseases originate from very different types of pathological conditions. Alcoholism, cortisone therapy, gout or hyperuricemia, sickle cell anaemia and others all lead, through various pathways, to the impairment of the medullary blood flow. In many instances, a compartment syndrome can be demonstrated in the femoral head. Death of the osteocytes follows bone marrow necrosis. Revascularisation originates in the periphery of the necrotic segment. Vascular buds and fibroblasts invade the medullary space. New bone is laid over the necrotic trabeculae. Mechanical failure results from changes in the bony framework at three different levels. The subchondral boneplate may be weakened by the process of revascularisation, the necrotic trabeculae may fail because of diminished stiffness and strength, and overloading has been demonstrated at the junction between dead and living bone. Elevation of the intramedullary pressure is the first objective sign of impending or established bone necrosis. Scintigraphy with Technetium 99 m - Sulphur colloid can now show the early stages of marrow necrosis. Roentgenographic changes only appear in a later phase of the disease. Aseptic necrosis must be considered as involving both hips, unless proven otherwise. Attention given to the "silent hip" may allow salvage and prevent the occurrence of osteo-arthritic changes leaving merely unilateral disease. As long as the geometrical shape of the femoral head is maintained operation may well prove useful. The aim at this stage is to prevent collapse. It is impossible to know in the early stages whether mechanical failure will occur, but there is general agreement that the femoral head will eventually undergo deformation. A spherical epiphysis is therefore considered a success. All the conservative methods aim to decompress the medullary cavity. Core biopsy, curettage, bone grafting and intertrochanteric osteotomy all have their advocates. After fracture of the subchondral bone plate has occurred, there is evidence that grafts are unable to restore the strength of the necrotic area. Intertrochanteric osteotomy brings under the main load-bearing zone a vital part of the femoral head. Varus osteotomy can be successful if necrosis has spared sufficient of the lateral portion of the head. Rotation osteotomies, as proposed by Sugioka, are more radical and difficult operations. The published results are promising. Revascularisation of the weight-bearing area by pedicle grafts has been attempted, alone or in addition to osteotomy.(ABSTRACT TRUNCATED AT 400 WORDS)