Myositis ossificans occurs when bone tissue develops where it shouldn’t, often in your muscle or soft tissues. Most people who have myositis ossificans develop it after a traumatic injury. But some rare types of myositis ossificans are hereditary. If you get myositis ossificans after an injury, you can usually treat it with nonsurgical options.
Myositis ossificans (my-uh-SY-tuss uh-SIH-fuh-kanz) is when a bone forms inside your muscle or other soft tissue. Usually, myositis ossificans develops after a traumatic injury. Most often, it affects large muscles, such as in your arms or legs.
When bone forms where it shouldn’t, you may develop a painful, tender lump. Myositis ossificans that develops after an injury is the most common type of heterotopic ossification.
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Myositis ossificans is most common in young, active people and athletes of all levels. It is also more likely to occur in people who are paralyzed from the waist down (paraplegia), even if they haven’t had an injury that started the symptoms.
Doctors classify myositis ossificans into two types:
When you are injured, your body immediately starts making new cells to heal itself. Nonhereditary myositis ossificans occurs when your body doesn’t make the right cells during the healing process. Instead of making muscle cells (fibroblasts), it creates new bone cells.
Myositis ossificans progressiva occurs because of a gene mutation. You may inherit this gene mutation from your parents. Or it may occur spontaneously (for no known reason).
The most common sign of myositis ossificans is a large lump beneath your skin. In around 4 in 5 people, the bump forms in your arm or leg muscle. People with paraplegia are more likely to have lumps grow around their hips or knees.
The lump may be:
As the lump gets bigger, it may reduce your range of motion. You’re more likely to have reduced range of motion if the growth is near a joint.
To diagnose myositis ossificans, your healthcare provider examines you and asks you about symptoms. They may touch the bony lump to see if it hurts or is warm.
They may also use imaging scans such as a:
Your provider may also perform a biopsy by taking a small sample of tissue from the growth. A laboratory examines the tissue to look for signs of myositis ossificans or other conditions with similar symptoms.
Often, myositis ossificans traumatica goes away by treating it at home. For all types of myositis ossificans, you may start with nonsurgical treatments, such as:
Your provider may also recommend physical therapy. Physical therapy helps you increase strength, flexibility and range of motion.
In severe cases, your provider may recommend surgery to remove the bony growth. Usually, you only need surgery if you have severe pain or limited function that doesn’t improve with nonsurgical treatment.
There’s no guaranteed way to prevent myositis ossificans. But you can reduce your risk of nonhereditary myositis ossificans by treating injuries properly, especially if you have a severe bruise or swelling. Immediately after injury, use the RICE method. RICE stands for:
Reducing your risk of injury may also reduce your risk for myositis ossificans. Proper conditioning, stretching and adequate rest are all crucial for injury prevention.
Usually, if myositis ossificans develops after an injury, it goes away with nonsurgical treatment. You may have limited range of motion or lingering stiffness for several months after treatment.
There’s no cure for myositis ossificans progressiva. This severe condition causes symptoms that progress throughout your life and may lead to a shorter lifespan.
You may also want to ask your healthcare provider:
What can I do to prevent myositis ossificans traumatica from developing again?
Some conditions can also cause painful lumps in your soft tissue. Your healthcare provider gives you tests during myositis ossificans diagnosis to rule out other conditions with similar symptoms, such as:
A note from Cleveland Clinic
Myositis ossificans occurs when bone forms where it shouldn’t, usually in your muscles or other soft tissues. Usually, myositis ossificans develops after a traumatic injury. Rarer hereditary types of myositis ossificans cause more severe symptoms. There’s no cure for these types of myositis ossificans. Doctors typically treat myositis ossificans traumatica with nonsurgical methods. For most people, this type of myositis ossificans goes away after several weeks or months.
Last reviewed by a Cleveland Clinic medical professional on 02/14/2022.
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Cleveland Clinic is a non-profit academic medical center. Advertising on our site helps support our mission. We do not endorse non-Cleveland Clinic products or services. Policy