Heterotopic ossification

Heterotopic ossification is the growth of extra bone within soft tissues such as muscle, tendons and ligaments, outside the normal skeleton. Most cases are acquired, appearing after soft tissue injury, surgery, burns, blast injuries or damage to the brain or spinal cord. Rare inherited forms, including fibrodysplasia ossificans progressiva and progressive osseous heteroplasia, start early in life and gradually restrict joint movement. The hip is most often involved, although the knee, elbow and shoulder can also be affected. Early symptoms are vague, with pain, warmth, redness and stiffness that can resemble infection, followed by worsening loss of movement that hampers walking. Imaging such as X-rays, computed tomography, bone scans or magnetic resonance imaging confirms it, and blood tests help exclude infection. It cannot usually be cured; anti-inflammatory medicines ease pain, preventive anti-inflammatory drugs or radiotherapy reduce new bone after surgery in high-risk people, and surgery can remove bone that limits movement.

Seek urgent care for a fracture after a minor fall, a hot swollen joint with fever, or sudden severe back pain. See a doctor for joint pain and stiffness lasting more than six weeks, loss of height, or if you have risk factors for weak bones and have never had a bone-density assessment. Call the local emergency number for any symptom that is sudden and severe. This page is a reference for healthcare professionals and does not replace an assessment.