Osteonecrosis of the Hip: Management in the Twenty-first Century

Osteonecrosis, also known as avascular necrosis or aseptic necrosis, is a disease of impaired osseous blood flow. The term aseptic necrosis had been commonly used in the past to distinguish osteonecrosis related to nonseptic causes from that related to septic causes. It commonly affects patients in the third, fourth, or fifth decade of life. Three hundred thousand to six hundred thousand people have osteonecrosis of the femoral head in the United States. The development of osteonecrosis can have a major impact on an individual's lifestyle. Since so many of the patients are young when they are diagnosed, they often need to alter their work and leisure activities. The ultimate goal of treating osteonecrosis of the hip is preservation of the femoral head. However, this is difficult since the condition is associated with a number of different diseases and neither the etiology nor the natural history has been definitively determined. The diagnosis of osteonecrosis accounts for 5% to 12% of total hip replacements performed1. It is difficult to obtain an understanding of the etiologic factors in osteonecrosis because the clinical composition of medical centers varies widely and because, for the most part, reported etiologic associations are based not on prospective studies but rather on cross-sectional and case-control studies. Osteonecrosis can be associated with traumatic or nontraumatic conditions. Since osteonecrosis eventually develops in only a relatively small percentage of patients with any of these conditions2, recent attention has been focused on understanding underlying predispositions to the development of osteonecrosis when challenged by environmental factors. Current interest is centering on genetic mutations leading to hypercoagulability, which results in microthrombosis and osteonecrosis when challenged by environmental (epigenetic) events. Patients with so-called idiopathic osteonecrosis most likely have some type of coagulation abnormality that has not been identified. ### Traumatic Osteonecrosis Osteonecrosis of the femoral …