Diphosphonate therapy in four patients with myositis ossificans.

Four patients with myositis ossificans were treated by surgery and administration of diphosphonate (EHDP) before and after the operation. Two of them were fibrodysplasia ossificans progressiva presenting the shortness of great toe and the characteristic hallux valgus.The recurrence of ectopic ossification was recognized in two patients with fibrodysplasia ossificans progressiva at one to four months after surgery, but other two patients did not show the recurrence. In one of the two patients showing no recurrence, the decrease in size of ossification was seen after 4 weeks' administration of EHDP and a stress fracture of the femur was recognized during the treatment.Use of EHDP for the patients with fibrodysplasia ossificans was considered doubtful, in spite of being effective for the patients with myositis ossificans.