The natural history of symptomatic osteonecrosis in adults with sickle-cell disease.

BACKGROUND: Adult patients with sickle-cell disease are at risk for the development of osteonecrosis of the hip. However, there is little information in the literature about the rate of progression of osteonecrosis once symptoms begin. The purpose of this study was to evaluate the natural history of the symptomatic hip in adult patients with osteonecrosis and sickle-cell disease.
METHODS: Ninety-two symptomatic hips in sixty-four consecutive adult patients with sickle-cell disease were initially evaluated between 1980 and 1987. Sixty symptomatic hips had radiographic evidence of osteonecrosis at the initial evaluation: forty-three were classified as stage II; two, as stage III; and fifteen, as stage IV, according to the system of Steinberg et al. The other thirty-two hips had lesions (stage I) that were evident only on magnetic resonance imaging. All patients were evaluated after a mean duration of follow-up of seventeen years.
RESULTS: Of the seventy-five hips without collapse of the femoral head at the initial evaluation, sixty-five demonstrated collapse within five years after the diagnosis. The average time between the diagnosis and collapse was forty-two months for stage-I hips and thirty months for stage-II hips. At the most recent follow-up examination, ninety hips had had collapse of the femoral head and eighty-eight of the ninety-two hips had had surgery because of intractable pain.
CONCLUSIONS: Symptomatic osteonecrosis of the hip in sickle-cell disease has a high likelihood of leading to femoral head collapse, necessitating surgical intervention. When osteonecrosis develops, the deterioration is rapid and, in most patients, operative intervention is necessary because of intractable pain. LEVEL OF EVIDENCE: Prognostic study, Level II-1 (retrospective study). See Instructions to Authors for a complete description of levels of evidence.