What is Myositis Ossificans

Myositis ossificans is a condition in which an area of injured tissue gradually turns into bone (calcifies). This can cause pain and stiffness in the area surrounding the bone growth.

Myositis ossificans happens when a deep bruise causes blood to collect in injured tissue (hematoma). Injured tissue may be fat, connective tissue, or muscle.

This condition most commonly affects the muscles of the thigh, buttocks, arm, or shoulder. It usually goes away after resting the injured area for up to 6–12 months, but more treatment may be needed in some cases.

What are the causes?

This condition is caused by a reaction to a hematoma. A hematoma may be a result of:

• An injury caused by a hard, direct hit (blow) to one area of the body.
• Multiple small injuries to the same area of the body.
• Having had surgery in the past 6 months.

In some cases, myositis ossificans may occur without a known cause (spontaneously), or it may be passed along from parent to child (inherited). Inherited myositis ossificans is very rare.

What increases the risk?

The following factors may make you more likely to develop this condition:

• Playing contact sports.
• Having a bleeding disorder, such as hemophilia.
• Taking blood-thinning medicines, such as aspirin.
• Not resting enough after an injury.
• Having burns on your body.
• Having a nerve injury, such as an injury to the spinal cord.

What are the signs or symptoms?

In many cases, this condition may not cause any symptoms. Possible symptoms include:

• Limited range of motion.
• Stiffness.
• Pain.
• Swelling.
• Tenderness when pressure is applied to the injured area.
• A hard lump that can be felt in the injured area.
• Numbness, tingling, or weakness.

How is this diagnosed?

This condition may be diagnosed based on:

• Your symptoms.
• Your history of recent injuries.
• A physical exam.
• Imaging tests. It may take up to 4 weeks for bone growth to be visible on these tests. Imaging tests may include:
  • X-rays.
  • CT scan.
  • MRI.
  • Ultrasound. This test uses sound waves to make an image of your affected area.
• Removal of a piece of the bone growth to be examined under a microscope (biopsy).

How is this treated?

Treatment for this condition depends on the severity. If you have no symptoms or if your symptoms do not bother you, you may not need treatment. However, if you do have symptoms, treatment may include:

• Physical therapy.
• A splint or a brace.
• NSAIDs to help reduce inflammation.
• Surgery to remove the bone growth. This may be necessary if you have symptoms that last longer than 6–12 months.

Follow these instructions at home:

If you have a splint or brace:

• Wear it as told by your health care provider. Remove it only as told by your health care provider.
• Loosen the splint or brace if your fingers or toes tingle, become numb, or turn cold and blue.
• Do not let your splint or brace get wet if it is not waterproof.
  • If you have a splint or brace that is not waterproof, cover it with a watertight covering when you take a bath or a shower.
• Keep the splint or brace clean.
• Ask your health care provider when it is safe to drive if you have a splint or a brace on your arm or leg.

Activity

• Return to your normal activities as told by your health care provider. Ask your health care provider what activities are safe for you.
• Avoid activities that cause pain or swelling.
• If physical therapy was prescribed, do exercises as told by your health care provider.
• Rest the affected area until your pain and swelling get better, or as long as told by your health care provider.

General instructions

• Do not use any tobacco products, such as cigarettes, chewing tobacco, and e-cigarettes. Tobacco can delay bone healing. If you need help quitting, ask your health care provider.
• Take over-the-counter and prescription medicines only as told by your health care provider.
• Keep all follow-up visits as told by your health care provider. This is important.

How is this prevented?

• Wear padding and protective equipment when you participate in sports or activities where contact occurs.
• If you are injured, rest and reduce your physical activity until your pain gets better.

Contact a health care provider if:

• Your symptoms do not improve after 2–4 weeks.