How often does Osteonecrosis occur in a bilateral fashion?
Approximately 50% of patients with symptomatic hip ON have asymptomatic disease in the contralateral hip at the time of initial presentation. Two thirds of these asymptomatic hips will eventually progress to late-stage ON. Consequently, bilateral hip MRI at time of presentation is recommended. Similar frequencies would be expected in ON of humeral head and knee. It is common to have multiple bony areas involved.
