Heterotopic ossification (HO) is the development of abnormal bone in soft (non-skeletal) tissue. HO can appear in many areas of the body, including the shoulder, arm, pelvis, and hip and knee joints. It occurs in many brain injured individuals and may develop within days following the injury or several months later. The cause of HO is unknown.

     Most cases of heterotopic ossification cause no significant additional physical limitations, but in a minority of patients, HO may result in a major limitation of joint motion. The first symptom you may notice is difficulty or limitation in your ability to perform activities of daily living, especially activities that require you to bend at the hips. However, sometimes the onset of HO is more rapid, and symptoms at that time may be swelling of one hip and warmth and redness overlying the swelling. In addition to decreased range of motion and swelling in the area of the HO, other symptoms may include increased spasticity, swelling of the entire leg, and/or elevated temperature.

     If you suspect you have HO, contact your physician. He/she will do an X-ray of your hips and knees, a special isotope bone scan, and blood tests. A medication called Didronel is available and can slow down or arrest the process if started early. If you have HO, watch your skin closely. The HO can increase the amount of pressure applied to the tissue under certain bony prominences.