Massive heterotopic ossification after distal femur fracture

Heterotopic ossification is the formation of lamellar bone in periarticular soft tissue that can be seen in paralysed patients or following trauma. It can cause significant burden to already debilitated patients. A 12-year-old boy with paraplegia due to neuromyelitis optica presented with progressive right knee pain and swelling. There was no history of trauma to the knee. Anteroposterior radiograph of femur at the initial presentation showed a supracondylar femur fracture for which casting was performed. Six weeks later, when casting was removed, swelling along with increased rubor in distal thigh region was noted. Radiography of the right femur revealed an unhealed distal femur fracture along with massive ossification extending from lesser trochanter to fracture line along the soft tissue around the femoral shaft. This case presented the clinical and imaging findings of a giant heterotopic ossification in the thigh region following an extra-articular fracture