Objective: To study demographic, clinical, and radiographic staging patterns in patients with multifocal osteonecrosis to facilitate earlier diagnosis and optimize treatment.
Methods: Multifocal osteonecrosis was defined as disease of 3 or more anatomic sites. Patients were characterized demographically, which included disease associations, corticosteroid and other agent usage, presenting joints, and symptomatology. Radiographically, patients were evaluated with plain radiographs and magnetic resonance imaging (MRI) scans of all joints to determine the presenting stage of the lesions.
Results: We found that 32 of 1056 (3%) osteonecrosis patients under our care had multifocal disease. Associated factors included systemic lupus erythematosus (13 patients), inflammatory bowel disease (5 patients), malignancy (4 patients), and renal transplantation (3 patients). Thirty of the 32 patients (94%) had a history of corticosteroid therapy, with the other 2 patients found to have a coagulopathy. All 32 patients had bilateral femoral head involvement and 30 of 32 had bilateral knee involvement, with the other 2 having only left knee lesions. Osteonecrosis was also seen in the shoulder (28 patients), ankle (8 patients), and 3 other sites. Overall, 201 sites were involved (6.3 per patient). The majority of joints presented in a pre-collapse stage (77%). Patients most commonly presented with hip or multiple joint symptoms (22 patients, 69%). In 8 patients, the knee was the sole presenting symptomatic joint and the ankle and shoulder were the sole presenting symptomatic joints in one patient each.
Conclusion: In patients with a diagnosis of osteonecrosis and complaints in other joints, these other areas should be fully evaluated with plain radiographs and, if inconclusive, with MRI. In patients with osteonecrosis not involving the femoral head, the patient's hips should be radiographically evaluated regardless of whether the patient is symptomatic. Patients diagnosed with osteonecrosis of the knee, shoulder, or ankle should have other joints evaluated, as such patients have multifocal disease roughly 50% of the time.