Heterotopic Ossifications of the Forearm: A Cause of Post-Traumatic Loss of Pronation-Supination

Abstract

HO is defined by the development of ectopic mature bone within nonosseous tissues. It is a well-described phenomenon that complicates forearm fractures, especially when there is an open fracture, a significant soft tissue injury, and associated neural axis or thermal injury. HO mainly forms near metal hardware and may lead to the formation of radio-ulnar synostosis. CT is superior to plain radiographs, as it identifies the ectopic bone earlier, defines its exact localization, and helps planning the surgical intervention. Radiologic features are variable; in the early stage, CT shows a low-attenuation mass with indistinct surroundings. As the ossification process progresses, zones of mineralization are visible before leading to the formation of mature cortical bone at the periphery (Figure 1 and 2: arrows). Hastings classification describes 5 classes according to how HO affects the forearm range of motion.