Does pain predict outcome in hips with osteonecrosis?

It generally is accepted that without specific treatment 70-80% of hips with clinically diagnosed osteonecrosis will progress to collapse. However, there are conflicting reports regarding the relationship between pain and outcome before femoral head collapse. Some surgeons are reluctant to operate on patients with asymptomatic or minimally symptomatic hips, assuming that these patients have a better prognosis than patients with pain. This study reviewed the outcome of 328 hips in 235 patients with nontraumatic osteonecrosis, all treated with core decompression and grafting. The preoperative stage, the extent of necrosis, and the Harris pain scores were correlated with the clinical and radiographic outcomes. Mean followup was 46 months. Patients with hips treated surgically did better as a group than patients with hips treated without surgery. A direct correlation was found between outcome and the stage and size of the necrotic lesion. Hips that had femoral head collapse were more painful than hips that did not have collapse and had a poorer outcome. Before collapse, outcome was correlated with the size of the necrotic lesion but there was no correlation with the preoperative pain level. These findings, although limited to patients with hips which had core decompression and grafting, support the observations of investigators who reported that most asymptomatic hips with osteonecrosis would progress without specific treatment. They also may apply to hips which have other forms of prophylactic treatment. Although several factors must be considered in determining the optimum treatment of hips with early stages of osteonecrosis, prophylactic treatment should not be withheld specifically because of the absence or paucity of pain.