Heterotopic ossification: Pathophysiology, clinical features, and the role of radiotherapy for prophylaxis

Heterotopic ossification (HO) is a benign condition of abnormal formation of bone in soft tissue. HO is frequently asymptomatic, though when it is more severe it typically manifests as decreased range of motion at a nearby joint. HO has been recognized to occur in three distinct contexts—trauma, neurologic injury, and genetic abnormalities. The etiology of HO is incompletely understood. A posited theory is that HO results from the presence of osteoprogenitor cells pathologically induced by an imbalance in local or systemic factors. Individuals at high risk for HO development frequently undergo prophylaxis to prevent HO formation. The two most commonly employed modalities for prophylaxis are nonsteroidal anti-inflammatory drugs and radiation therapy. This review discusses HO pathophysiology, clinical features, and the role of radiotherapy for prophylaxis.