Bone loss and recovery in regional migratory osteoporosis

Regional migratory osteoporosis (RMO) is a migrating arthralgia of the weight-bearing joints of the lower limb associated with focal osteoporosis. Little information is available on a quantitative assessment of systemic or local osteoporosis. In this study, we report three cases of RMO in which spine, hip and whole body serial assessments of bone mass have been evaluated to outline their extent and time course of changes. Systemic osteoporosis, with a prevalent involvement of the mainly trabecular skeletal sites, was present in all the patients, with T-scores below -2.5 at both the lumbar spine and femoral neck. Bone loss in acute episodes ranged from -75.5% to -14.7% and appeared related to the severity of the episode. In acute episodes the demineralizing process affected the whole limb from the hemipelvis to the foot: the bone loss ranged from -33.6% to -3.5% at sites with prevalent trabecular composition and from -19.1% to -1.1% at sites with prevalent cortical composition. Bone recovery was complete in one episode out of six. In the other five cases, the average residual bone loss was 26% (range 13.9-32.7%). Our observations suggest that RMO occurs in subjects with systemic osteoporosis and densitometric assessment may aid in the clinical management.