Condition: Heterotopic ossification (HO) is the abnormal growth of bone in locations of the body other than the skeleton.
Background: HO commonly occurs following spinal cord injury, traumatic brain injury, brain damage due to loss of oxygen, stroke, severe burns, fractures, and joint replacement surgery.
Risk Factors: Risk factors for HO include male gender, long bone fractures, immobility, the presence of a coma for more than two weeks, complete spinal cord injury, spinal cord injury at chest level, osteoarthritis of the joint, previous occurrence of HO, and severe tissue injury.
History and Symptoms: HO commonly occurs in hips and knees after spinal cord injury; hips, shoulders, or elbows after traumatic brain injury; and the elbow after stroke or severe burn. HO is observed as early as 2 weeks after injury. Decreased range of motion, pain, swelling, and tenderness occur early. As the abnormal bone mass develops over the course of months, the pain and swelling may decrease, but the bone mass may result in pressure ulcers, nerve compression, additional decreases in range of motion, deformities, joint stiffness, and disability.
Physical Exam: A physical exam will be performed to assess the range of motion, pain, swelling, and tenderness of the affected area.
Diagnostic Process: A bone scan is used to definitively diagnose HO. X-rays are useful in later disease stages, but early on in disease, these images are not decisive. Laboratory blood tests may be used to examine levels of enzymes in the blood.
Rehab Management: Physical therapy is used to improve range of motion and limit muscle stiffness and pain. Medications such as non-steroidal anti-inflammatory drugs (indomethacin) and the drug etidronate can be used to minimize bone formation after spinal cord injury or surgery. Surgery to remove sites of HO is recommended only when mobility or self-care may be improved by the surgery. Radiation directed at the sites where HO typically develops following surgery may also be beneficial to prevent recurrence.
Other Resources for Patients and Families: Information and support for patients and families is available and is dependent on the cause of the condition.