OVERVIEW

What is heterotopic ossification?

Heterotopic ossification refers to the formation of bone tissue in soft tissues where bone is not normally present, due to the presence of osteoblasts. This condition can lead to severe movement dysfunction.

Heterotopic ossification often occurs around large joints (such as the hip or elbow). Reports indicate that its incidence after acetabular surgery is as high as 90%, while after elbow fracture or dislocation surgery, it ranges from 5.5% to 18.8%.

How is heterotopic ossification classified?

Heterotopic ossification can generally be divided into three categories based on its cause: traumatic, neurogenic, and genetic.

• Traumatic heterotopic ossification: Typically associated with orthopedic injuries, such as hip fractures, elbow or knee dislocations, and hip joint fractures.

• Neurogenic heterotopic ossification: Related to central nervous system trauma, such as brain or spinal cord injuries.

• Genetic heterotopic ossification: Relatively rare, primarily occurring in patients with progressive osseous heteroplasia or fibrodysplasia ossificans progressiva.

SYMPTOMS

What are the manifestations of heterotopic ossification?

In the early stages of heterotopic ossification, swelling and pain may occur, possibly accompanied by limited movement. As the condition progresses, the formation of bone tissue can lead to loss of joint mobility.

CAUSES

What Causes Heterotopic Ossification?

The exact cause of heterotopic ossification remains unclear, but it may be related to excessive limb movement during the early stages of injury.

It commonly occurs in cases of central nervous system injuries (such as traumatic brain injury, spinal cord injury, encephalitis), multiple trauma, or hip surgery. Additionally, congenital factors like fibrodysplasia ossificans progressiva and Albright hereditary osteodystrophy can also lead to this condition.

DIAGNOSIS

What tests are generally needed to diagnose heterotopic ossification?

Generally, a standard X-ray can confirm heterotopic ossification. If the diagnosis remains unclear, additional tests such as CT, MRI, or bone scans may be required to assist in the diagnosis.

How to differentiate between heterotopic ossification and myositis ossificans?

Both heterotopic ossification and myositis ossificans can cause movement disorders, but they are distinct conditions.

• Myositis ossificans: Results from tissue organization due to injury or bleeding, forming hard nodules or contractures. It does not necessarily occur around joints but is concentrated within the muscles.

• Heterotopic ossification: Typically has a clear history of local trauma. Local pain symptoms may not be obvious, but there is usually some degree of restricted movement.

Which bone tumors should heterotopic ossification be differentiated from?

It generally needs to be distinguished from parosteal osteosarcoma and osteochondroma.

TREATMENT

Which department should I visit for heterotopic ossification?

The choice of department depends on the injury. For cases related to bone trauma, visit the orthopedics department; for cases related to nerve damage, visit the neurosurgery department.

How is heterotopic ossification treated?

In the early stages of heterotopic ossification, nonsteroidal anti-inflammatory drugs (NSAIDs) should be used to suppress inflammation and pain, thereby reducing its formation.

If treatment is ineffective and heterotopic ossification continues to progress, surgical removal of the lesion may be performed, supplemented with preventive measures to minimize recurrence.

What are the current treatment or preventive measures for heterotopic ossification?

Prevention is more important than treatment for heterotopic ossification. The two most commonly used preventive methods are NSAIDs and single-dose radiotherapy.

• NSAIDs: Prevent heterotopic ossification by suppressing inflammation. Indomethacin is commonly prescribed for a treatment period of 6 weeks.

• Single-dose radiotherapy: A single dose of radiation can inhibit the rapid proliferation and differentiation of osteoprogenitor cells, thereby preventing heterotopic ossification.

Which patients with heterotopic ossification require surgery?

Asymptomatic patients with no significant impact on joint function do not require surgery and can be managed conservatively with medication.

Surgery is considered only when heterotopic ossification impairs joint function or causes severe pain. For example, if the elbow joint has a flexion-extension range of 30–130° and forearm rotation of 50° pronation and 50° supination, over 90% of daily activities can be performed, meaning there is no functional impairment, and surgery is unnecessary.

Additionally, children differ from adults—heterotopic ossification in children may resolve spontaneously. For instance, once central nervous system lesions recover, heterotopic ossification may disappear on its own.

When is the optimal time for surgery after injury in heterotopic ossification?

The timing of surgery remains controversial, but it is generally recommended to wait at least 4 months post-injury. By then, fractures and wounds have healed, inflammation has subsided, and the condition is relatively stable.

Is the recurrence rate high after surgery for elbow heterotopic ossification?

After heterotopic ossification excision and capsular release, the recurrence rate is low, and most patients regain functional range of motion in the elbow joint.

DIET & LIFESTYLE

What should patients with heterotopic ossification pay attention to in their diet?

There are no specific dietary restrictions.

In the prevention of heterotopic ossification, should joint movement be completely prohibited after injury?

Some studies suggest that heterotopic ossification may be related to excessive limb movement in the early stages of injury. Does this mean no movement at all after joint injury?

No. After joint injury, appropriate joint movement exercises should still be performed under the guidance of a professional physician. On one hand, this can prevent joint adhesions, and on the other hand, it can help preserve joint mobility that may gradually be lost as heterotopic ossification matures.

Currently, dynamic braces are available on the market to help patients counteract muscle contractures. Wearing such braces allows for functional joint movement exercises during the day and immobilization at night. Patients in need can consult their physicians for further information.

PREVENTION

Can heterotopic ossification be prevented?

Nonsteroidal anti-inflammatory drugs, bisphosphonates, and radiation therapy can to some extent prevent the occurrence of heterotopic ossification.