Heterotopic ossification (HO) occurs when bone tissue develops in your soft tissues. Often, people get HO after an injury or major surgery. Genetic HO is rarer and more severe. In HO, you develop a bony, painful lump underneath your skin. If the lump is near a joint, it may restrict your range of motion.
Heterotopic ossification (HO) means bone grows in tissues where it typically wouldn’t. These bone fragments are extraskeletal bone. They often form after an injury. But they may occur for no known reason.
For most people, extraskeletal bone fragments are small and don’t cause many symptoms. Large bone pieces may restrict your movement and cause severe problems.
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Heterotopic ossification can be:
Anyone can get nongenetic heterotopic ossification. You're most likely to develop it if you have a history of injuries or surgeries.
Up to 3 in 4 people who have HO can point to trauma that led to the condition. It commonly affects people who have:
About half of all people with non-genetic HO are adults in their 20s and 30s. Men are slightly more likely than women to get HO.
The genetic types are rare. Experts estimate that fewer than 5,000 people worldwide have the genetic diseases that cause HO.
HO can affect any part of your body. But you are most likely to get it in areas that are most likely to get injured, such as your:
Often, you develop heterotopic ossification after an injury. It may also occur after surgery. People who have a total hip replacement can occasionally develop HO, but it rarely causes symptoms.
You have a higher risk of developing HO if you have had a:
Rarely, some genetic diseases cause HO, including:
Heterotopic ossification symptoms can vary. They depend on how far the disease has progressed and how severe it is. In its early stages, heterotopic ossification often causes:
As heterotopic ossification advances, you may notice a bump under your skin. The bump may grow quickly into a large lump that you can’t easily move with your fingers. It may be tender to the touch.
In later stages, the lump may harden. If it’s near a joint, such as your hip or shoulder, it may restrict your range of motion.
If you have FOP that leads to heterotopic ossification, you may have:
As FOP progresses, most people have severe symptoms, including difficulty walking or even breathing. This rare cause of HO can shorten your lifespan.
POH is associated with symptoms that affect your skin. In this form, bones form in subcutaneous tissue, the layer of fat between your skin and muscle. As the disease progresses, bones may form in your deeper connective tissues.
To diagnose heterotopic ossification, your provider may use imaging tests such as a:
If your provider suspects you have a genetic form of heterotopic ossification, they may avoid a biopsy. In certain types of genetic HO, any surgery can increase your risk of bone growths spreading to other parts of your body.
If you develop HO after total hip arthroplasty (hip replacement), your provider may use grading scales to assess how much HO has progressed.
One of the most widely used grading systems is the Brooker classification. This scale rates heterotopic ossification as:
Other grading scales look for similar signs of HO. The most significant factor in HO severity is whether you have bone spurs and how far apart the spurs are.
Heterotopic ossification treatment varies depending on symptoms, type of HO and the condition’s progression. In general, your healthcare provider may recommend:
If you’re scheduled for orthopedic surgery, your provider may prescribe treatments to lower your risk of HO. You have a higher risk of HO after hip replacement surgery if you also have:
Your provider may use a preventive treatment to improve your chance of an excellent total hip arthroplasty outcome. Some studies have shown that taking nonsteroidal anti-inflammatory drugs (NSAIDs) before or immediately after surgery can decrease your risk of postsurgical HO.
There’s no guaranteed way to prevent heterotopic ossification. But you may lower your risk by treating injuries right away with rest, ice, compression and elevation (RICE). You may also prevent injuries with strength training, stretching and rest.
Sometimes. People with nongenetic HO often have a full recovery. Often, HO that develops after an injury goes away with nonsurgical treatment such as rest, ice and light stretching.
There’s no cure for genetic types of HO. You may manage symptoms with treatment, but the disease continues to progress.
You may also want to ask your healthcare provider:
Yes. Pain near the affected area is one of the most common symptoms of heterotopic ossification. Often, pain worsens as the bony growths get bigger.
But there is good news if you develop heterotopic ossification after an injury or surgery. Most people with nongenetic HO fully recover with treatment.
No. Some conditions can increase your risk of developing HO after surgery. But there’s no proven link between osteoporosis and HO.
A note from Cleveland Clinic
Heterotopic ossification occurs when bone tissue develops in your soft tissues. Some people develop HO after an injury or surgery. Others have genetic types of HO. Genetic HO is rare and causes severe symptoms. People with nongenetic HO can often treat it with nonsurgical methods. You may take NSAIDs or work with a physical therapist to treat nongenetic HO.
Last reviewed by a Cleveland Clinic medical professional on 03/21/2022.
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