Regional migratory osteoporosis of the lower extremities with vertebral osteoporosis.

Regional migratory osteoporosis is a disorder of unknown etiology, characterized by successive episodes of joint pain, accompanied by localized osteoporosis. The disorder affects the lower limbs, usually the region of the foot, knee, or hip, and each episode usually lasts several months and is followed by spontaneous recovery. This disorder has not previously been reported to cause episodes of vertebral osteoporosis. We describe three patients in whom regional osteoporosis, involving the lower limbs, was associated with simultaneous vertebral osteoporosis indistinguishable from idiopathic osteoporosis. These cases suggest that this disorder might be responsible for some cases of apparent idiopathic spinal osteoporosis.