Definition

Heterotopic ossification (HO) is the growth of bone in abnormal places like soft tissue. It can occur anywhere in the body. The hip, knees, shoulders and elbows are the most common locations. This condition can vary from minor to heavy growth.

The sooner this condition is treated, the better the outcome. If you suspect you have HO, contact your doctor promptly.

Causes

The exact cause of HO is unknown. There may be a genetic link to the development of this condition.

Risk Factors

Although the exact cause is unknown, there are well known factors that increase your chance of getting HO. Tell your doctor if you have any of these risk factors:

  • Traumatic brain injury or stroke
  • Spinal cord injury (especially recent, 1-4 months)
  • Hip surgery or other joint surgery
  • Burns
  • Long period of immobility
  • Joint infection
  • Trauma to muscle or soft tissue

Symptoms

Symptoms vary based on the severity and site of the bone growth. If you have any of these, do not assume it is due to HO. These symptoms may be caused by other conditions. Tell your doctor if you have any of these:

  • Decreased range of motion
  • Swelling or redness to joint(s)
  • Pain
  • Fever

Diagnosis

Your doctor will ask about your symptoms and medical history. A physical exam will be done. You may be referred to a specialist. An orthopedic doctor focuses solely on problems of the bones and joints.

Tests may include the following:

  • Bone scan —a test that determines mineralization of the bones and detects abnormal bone in tissue
  • Serum alkaline phosphatase level—increased levels of this substance in the blood is linked to heterotopic ossification
  • Several tests have been studied for HO. These are used less often and include:
    • Serum osteocalcin
    • C-reactive protein
    • Erythrocyte sedimentation rate
    • Creatine kinase
    • Urine hydroxyproline, deoxypyridinoline, and prostaglandin
  • X-ray —may only be able to detect abnormal bone in later phases of the disease

X-ray of Pelvic Repair

repiared pelvis x-ray
HO may not show up on x-ray until later stages.
© 2009 Nucleus Medical Art, Inc.

Treatment

Talk with your doctor about the best plan for you. Options vary based on the scope of the disease, and include the following:

Physical Therapy

Therapy is an important part of treatment. Range of motion exercises will help to maintain mobility. It can also keep the disease from getting worse. Therapy may also include some stretching and strength training.

Medications

Your doctor may prescribe:

  • Bisphosphonate drug (eg, etidronate (Didronel))—to block calcium from depositing in new boney growths
  • Nonsteroidal antiinflammatory drugs (NSAIDs)—to help prevent more bone growth in soft tissue

Radiation Therapy

Radiation is used to prevent abnormal bone growth, mainly after hip surgery.

Surgery

Surgery may be used to remove the abnormal bone and increase range of motion. Radiation and medications are often given after surgery, since the disease can recur.

Prevention

HO is not well understood. If you have any of the risk factors above, talk to your doctor about any symptoms you may have. Discuss whether you need to take preventative measures.