Heterotopic Ossification

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Condition: Heterotopic ossification (HO) occurs when bone grows abnormally outside of the skeletal system.

Background: HO can occur after a spinal cord injury, traumatic brain injury, stroke, severe burns, fractures, and joint replacement surgery. A physical medicine and rehabilitation (PM&R) physician, also known as a physiatrist, is often involved in the care of people with these conditions and are skilled in identifying signs and symptoms of HO as well as direct treatment.

Risk Factors: The likelihood of developing HO is higher with fractures of long bones, prolonged immobility, extremity swelling, trauma, pressure ulcers and being in a coma for more than 2 weeks. Common locations where HO can develop include the hip, knee, elbow, shoulder, and knee.

History and Symptoms: Symptoms of HO can include difficulty in moving the joint, pain, swelling, warmth and redness. These symptoms can start 2 weeks to 12 months after the initial injury or event.

Physical Exam: Sometimes there are no symptoms but during examination there can be pain or tenderness on movement of the joint, difficulty moving the joint, swelling, redness, warmth and low grade fever. 

Diagnostic Process: There are several laboratory studies available to look for evidence of HO but these are unable to confirm a diagnosis. A triple phase bone scan is the main study used for confirmation of HO. A radiograph or x-ray can detect HO but only after 3 weeks to 2 months.

Rehab Management: A PM&R physician will work together with a physical and/or occupational therapist to control muscle spasticity, decrease pain and improve the mobility of the affected joint to prevent further growth of HO. Treatment may include indomethacin and alendronate. In cases in where mobility and self-care activities have been affected, referral to a surgeon for removal might be appropriate. However, surgery cannot be performed until the bone formation has matured without further growth.

Other Resources for Patients and Families: Patients, family and caregivers will be educated on what to expect when diagnosed with HO, what additional complications are possible and what treatment options are available at each stage of the condition.

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