Posttraumatic Heterotopic Ossification

Updated: Aug 01, 2023
  • Author: Auri Bruno-Petrina, MD, PhD; Chief Editor: Stephen Kishner, MD, MHA  more...
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Practice Essentials

In 1918, Dejerine and Ceillier first described heterotopic ossification (HO) in paraplegic patients injured in World War I, referring to the process as paraosteoarthropathy. HO has been defined as the formation of mature lamellar bone in soft tissues. The process involves true osteoblastic activity and bone formation. HO has been reported in cases of brain injury, spinal cord injury, stroke, poliomyelitis, myelodysplasia, tabes dorsalis, carbon monoxide poisoning, spinal cord tumors, syringomyelia, tetanus, and multiple sclerosis. This condition also has been reported after burns and total hip replacement/joint arthroplasty. [1, 2]

Several terms have been used to describe the condition, including heterotopic ossification, ectopic ossification, and myositis ossificans. HO usually involves the large joints of the body (eg, hips, elbows, shoulders, knees). Excessive bone formation may result in significant disability by severely limiting the range of motion (ROM) of these joints (see image below).

This radiograph clearly demonstrates fairly extens This radiograph clearly demonstrates fairly extensive heterotopic ossification at the bilateral hip regions. The extensive bone formation shown here makes it easy for the viewer to understand why a patient with HO could present with complaints such as pain, swelling, palpable mass, and decreased range of motion.

In a study of patients who suffered a traumatic spinal cord injury, Ohlmeier et al, examining the frequency of heterotopic ossification (HO) in muscle groups around the hip, found HO to be most prevalent in the gluteal muscle group (55.8%). The second-highest prevalence (31.1%) was reported to be in the deep muscle group. [3]

The following 3 categories of HO have been described:

  • Myositis ossificans progressiva - This is a rare metabolic bone disease in children with progressive metamorphosis of skeletal muscle to bone; it is characterized by an autosomal dominant pattern of genetic transmission.

  • Myositis ossificans circumscripta without trauma - Also referred to as neurogenic HO, this is a localized soft-tissue ossification occurring after neurologic injury or burns.

  • Traumatic myositis ossificans - This condition occurs from direct injury to the muscles. Fibrous, cartilaginous, and osseous tissues near bone are affected; the muscle may not be involved.

Related Medscape Reference topics:

Heterotopic Ossification [Physical Medicine and Rehabilitation]

Heterotopic Ossification Imaging [Radiology]

Heterotopic Ossification in Spinal Cord Injury

Pediatric Fibrodysplasia Ossificans Progressiva (Myositis Ossificans)

Traumatic Heterotopic Ossification

Related Medscape resource:

Resource Center Joint Disorders

Signs and symptoms of posttraumatic heterotopic ossification

The earliest sign of heterotopic ossification (HO) often is decreased joint range of motion (ROM). Other findings include swelling, erythema, heat, pain with ROM testing, and contracture formation, but the condition may be occult. Fever also may be present. Patients with HO can experience pain, increased spasticity, vascular and nerve compression, and lymphedema.

Workup in posttraumatic heterotopic ossification

Because of the limitations of plain radiography in the imaging of heterotopic ossification (HO)—this modality may not show evidence of HO until 4-5 weeks after injury—radionuclide bone scanning is the preferred diagnostic test for earlier detection of the condition. [4]

The diagnosis of HO following brain injury typically is made by clinical examination and by assessing for elevations in alkaline phosphatase.

Management of posttraumatic heterotopic ossification

The role of physical therapy in patients with heterotopic ossification (HO) is controversial. The major goal of treatment is to maintain ROM and thereby preserve function; however, opinions differ regarding ROM exercises for patients with HO.

Surgery for removal of ectopic bone should be undertaken only for clear functional goals, such as for improved standing posture or ambulation or for independent dressing and feeding. In general, surgery is not undertaken earlier than 18 months after injury.

Excision should be considered for patients in whom shoulder motion is severely limited by extensive heterotopic bone, especially if dynamic electromyography studies reveal volitional capacity for the various shoulder muscles. Excision may also be undertaken to improve passive shoulder functions.

lf joint deformity from HO results in significant functional limitations such as difficulty with hygiene, sitting, or ambulation, surgical resection of HO may be indicated. Surgery may also be appropriate if an underlying bone mass contributes to repeated pressure sores.



The specific cause and pathophysiology of heterotopic ossification (HO) remain uncertain, but the condition appears to involve the inappropriate differentiation of mesenchymal cells into osteoblastic stem cells in response to still-unidentified inducing agents.

HO may be due to an interaction between local factors (eg, the pool of available calcium in adjacent skeleton, soft-tissue edema, vascular stasis tissue hypoxia, mesenchymal cells with osteoblastic activity) and an unknown systemic factor or factors. The basic defect in HO is the inappropriate differentiation of fibroblasts into bone-forming cells. Early edema of connective tissue proceeds to tissue with foci of calcification and then to maturation of calcification and ossification.




United States

The reported incidence of heterotopic ossification (HO) varies. In cases of severe trauma or insult to the central nervous system (CNS), 10-20% of patients develop HO, and the condition has been observed in 20% of patients with severe brain injury. The incidence is higher in patients who undergo open reduction and internal fixation of a fracture. With an elbow fracture, dislocation, or fracture-dislocation, the incidence of traumatic HO at the elbow approaches 90%. Traumatic HO of the elbow occurs in 20% of forearm fractures. Fifty-five percent of patients with hip fractures develop HO. The incidence increases to 83% if open reduction and internal fixation are performed. The incidence is similar in the upper and lower extremities.

An association has been cited between spasticity and HO. The incidence is higher in a spastic extremity; 84% of patients with HO had spasticity, and 54% of patients with HO had no spasticity. HO is seen in the elbow in 4% of patients with traumatic brain injury (TBI); however, if fracture or dislocation is associated with brain injury, the incidence of HO rises to 89%.

Related Medscape Reference topics:

Classification and Complications of Traumatic Brain Injury

Neurocritical Care for Severe Pediatric Traumatic Brain Injury

Traumatic Brain Injury (TBI) - Definition, Epidemiology, Pathophysiology


Studies from Europe and Japan have shown the incidence of HO to range between 11% and 76%, depending on the population studied and on the method of detection.


Only 10-20% of all heterotopic ossification (HO) patients have functionally significant deficits.


No race predilection exists for heterotopic ossification.


The development of heterotopic ossification is independent of the patient's sex.


An increased incidence of heterotopic ossification (HO) has been found in persons over age 30 years. The incidence of HO in children appears to be lower than that in adults (8-22.5%).