Aseptic Femoral Head Destruction

Degenerative arthritis is characteristically a slowly progressive process, developing over a period of years, in which mechanical cartilage wear leads pain, joint space narrowing, and osteophytes. Bone destruction, which is a feature of joint infection and inflammatory arthritis, is characteristically absent. However, rare patients without infection or inflammatory arthritis develop a painful, destructive arthritis, in which a large portion of the femoral head may undergo osteolysis. The condition has been described under several terms, including rapidly destructive hip disease, rapidly destructive osteoarthritis of the hip, rapidly destructive arthrosis of the hip joint, and rapidly destructive arthropathy. Because the time course of this arthritis may not be known, Professor Lester Layfield and Professor Julia Crim from the University of Missouri suggest that the term destructive arthropathy of the femoral head is preferable. Etiology of destructive arthropathy of the femoral head is still unclear. It has been proposed that subchondral insufficiency fracture, sometimes related to intra-articular steroid injection, is the initial trigger. Some researchers have suggested overactivation of osteoclasts by unknown tissue factors may be a prime causative factor.

Layfield and Crim reviewed the cases of destructive arthropathy presenting to their institution. They reviewed medical record of each case for possible causes of femoral head destruction, clinical presentation, laboratory values, imaging studies, and pathologic diagnoses. They also reviewed imaging studies and pathology specimens for their study. In their study they looked carefully at the clinical history of 8 women and 12 men (ages 47-83 years) who had severe hip pain and were documented as having destructive arthropathy on radiographs and histopathology in the absence of infection or inflammatory arthritis. The degree of femoral head destruction as estimated on radiographs ranged from 25% to 100%. Time course to destruction was not known in most patients. Imaging studies showed extensive bone loss, and a ragged and irregular shape of the femoral head. Periarticular osteopenia and bony erosions were also present, mimicking infection.

When the authors conducted gross examination of femoral heads, complete loss of the articular cartilage associated with destruction of the subchondral bone plate was observed. The femoral heads were markedly deformed. On microscopic examination the authors found an increased number of osteoclasts resorbing bone trabeculae. Microfractures, necrotic bone fragments, and granuloma-like aggregates of histocytes were variably present. There was no histologic evidence of acute or chronic inflammation. Not all these features were invariably present within any given case: Destruction of the articular cartilage was present in 100% of cases and necrotic bone fragments were present in only 70% cases. Disorganized bone remodeling was seen in 85% of cases and vascularized fibromyxoid stroma was seen in 70% of overall cases.

The authors suggest that the term destructive arthropathy of the femoral head be used when radiographs show 25% or more destruction of the femoral head. The diagnosis of destructive arthropathy is confirmed by pathologic evaluation, where destruction of articular cartilage and subchondral bone, necrotic bone fragments, increased numbers of osteoclasts, and granulomas are present, but signs of infection are absent. The importance of recognizing destructive arthropathy lies in distinguishing it from infection, both by joint aspiration and by pathologic evaluation of the femoral head.