Painful knees in older patients: radionuclide diagnosis of possible osteonecrosis with spontaneous resolution.

The syndrome of osteonecrosis of the femur at the knee presents as sudden onset of knee pain in elderly patients. It is classically associated with a subchondral radiolucency and a positive radionuclide bone scan. The lesion may progress to collapse of the bone. In this report, twelve cases are described in which the clinical entity of osteonecrosis of the femoral condyle was diagnosed because the patients had a clinical picture identical to that of osteonecrosis and also had positive bone scans. However, roentgenographic changes supposedly diagnostic of the condition were not seen. In twelve patients, arthrotomy was avoided. They became asymptomatic and their bone scans returned to normal in a few months.