Heterotopic Ossification

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Condition: Heterotopic ossification (HO) occurs when bone grows abnormally outside of the bones (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 is skilled in identifying signs and symptoms of HO as well as providing treatment.

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

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

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

Diagnostic Process: Several laboratory studies are available to look for evidence of HO, but these cannot 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 three weeks to two 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.

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 HO.

Patient and Family Handouts (printable PDF):

Heterotopic Ossification - English


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