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Since the advent of potent antiretroviral therapy in 1996, previously unrecognized complications of HIV infection and its therapy have emerged. One such complication, osteonecrosis of the hip and other bones, has been estimated to develop 10 times more often in HIV-infected individuals than in the general population.
To document the incidence of this condition, NIH researchers studied HIV-infected patients without hip or groin pain. Of 339 patients who underwent an initial magnetic resonance imaging (MRI) scan of the hips, 15 (4.4%) were found to have osteonecrosis. Of the remaining 324 patients, 239 had a second MRI performed 17 to 31 months later. Three such patients showed evidence of osteonecrosis, for an incidence of 0.65 cases per 100 person-years.
To determine the natural history of the condition, the researchers followed 22 patients with symptomatic osteonecrosis (median follow-up, 26 months). Of these, 13 underwent total hip replacement surgery at a median of 10 months after diagnosis. In contrast, during a median follow-up of 5.7 years, only 2 of 18 patients with asymptomatic osteonecrosis required hip replacement surgery (P=0.003). For both symptomatic and asymptomatic patients, only those with >50% femoral-head involvement on the initial MRI later required total hip replacement.
Morse CG et al. The incidence and natural history of osteonecrosis in HIV-infected adults. Clin Infect Dis 2007 Mar 1; 44:739-48.
Comment
This small, nonblinded study combined prospective and natural history elements, making it somewhat confusing. However, the findings demonstrate a very high rate of osteonecrosis of the hip among HIV-infected patients and emphasize the need to consider an MRI in HIV-infected patients with hip or groin pain. One caveat: In the asymptomatic group, the osteonecrosis detected by MRI remained stable or improved in most patients. Hence, screening for osteonecrosis in the absence of symptoms may not be useful.