Joint imaging in regional migratory osteoporosis.

We describe 4 patients (3 males aged 54-59, 1 female aged 25) with regional migratory osteoporosis (RMO). All patients had at least 2 episodes of periarticular osteoporosis. The interval between attacks ranged from 5 months to 11 yr and attacks lasted from 3 months to 2 yr. In 2 cases septic arthritis was initially suspected. The ankle joints were affected in 3 patients, hips in 2 and knees in 2. An unusual feature in 2 patients was involvement of the small joints of the foot demonstrated by 99mTc-methylene diphosphonate (99mTc-MDP) joint imaging. Joint imaging corroborated the clinical diagnosis in 2 patients before regional osteoporosis was visible radiologically. As there are no specific laboratory features of RMO, joint imaging may be helpful in the diagnosis of suspected cases before the development of radiographic stigmata.