Fractured heterotopic bone in myositis ossificans traumatica.

OBJECTIVE: To discuss the case of a patient with an acute fracture occurring through preexisting, quiescent, posttraumatic heterotopic bone formation of the gastrocnemius muscle. The lesion demonstrated a previously unreported pattern of healing. This case serves to demonstrate an infrequent event with a rare and heretofore unreported sequella. CLINICAL FEATURES: A 54-year-old man with preexisting, mature heterotopic bone within the left gastrocnemius muscle experienced reinjury to the site. The preexisting heterotopic bone was a result of a sporting injury that had occurred 32 years previously. At the time of the new injury, the patient experienced immediate, severe pain. Radiographs demonstrated a nondisplaced oblique fracture through the preexisting heterotopic bone. INTERVENTION AND OUTCOME: The patient was treated with protective wrapping and physiotherapy modalities. Because only the heterotopic bone was involved, the leg was not placed in a cast. Follow-up radiographs obtained 14 weeks later showed callus formation about the fractured site and evidence of union. CONCLUSION: Fractures occurring through mature heterotopic bone formations, such as those seen in myositis ossificans traumatica, are infrequent; callus formation with union of the fractured fragments is an even rarer occurrence.