Pathophysiology of heterotopic ossification.

Heterotopic ossification (HO) is a pathologic condition that leads to the development of bone within nonosseous soft tissues. A common site for HO development is at the hip. The bone that forms is believed to develop through stimulation by cellular mediators and altered neurovascular signaling. Heterotopic ossification can be a debilitating disease leading to pain, edema, and stiffness. This only compounds already-debilitating comorbid conditions such as a spinal cord injury, head injury, or trauma. Several factors, including prostaglandin E2, bone morphogenetic protein, and the inflammatory process, are believed to contribute to the development of HO. The full scope of pathophysiology contributing to HO is not fully understood.