Osteopenia after ankle fractures. The influence of early weight bearing and muscle activity.

Fifty-seven patients surgically treated for ankle fractures were followed for two years with bone mineral content (BMC) estimations at various levels of both lower extremities. Maximum BMC reduction was seen four months after operation. Bone mineral was partly regenerated during the remainder of the first year. There was hardly any regeneration during the second year. The persisting bone mineral deficit was between 3.5% and 9% depending on the region measured. BMC changes were minor in the contralateral limb and mainly consisted of a slight gain. During the first six postoperative weeks, patients (1) performed active movements of the ankle and subtalar joints but did not bear weight; (2) wore a plaster of paris cast without bearing weight; or (3) bore full weight in a plaster cast. The bone mineral loss was similar in the three treatment groups.