A healthy living blog from Marshfield Clinic Health System

​​​​​​​​​​​​Myositis ossificans: Abnormal bone tissue growth in muscles

Examining patient arm

A bony mass can form after an injury that limits range of motion, can become painful and limit the healing process.

​​​​​​​​​​​​Myositis ossificans may sound like a complicated condition, but this abnormal bone-tissue growth is a somewhat common sports injury. This condition is more likely in active young adults and athletes. Sustained at any level of play or competition, ​​​​​​​​​​​​myositis ossificans is the formation of bone tissue inside muscle tissue after a traumatic injury to the area.

​Deep-muscle bruising or repeated muscular trauma to the same spot usually is the cause of this injury. Bad muscle strains rarely result in ​​​​​​​​​​​​myositis ossificans. After the injury, the body begins to deposit bony tissue instead of muscular tissue at the healing site, eventually causing the formation of a hard lump you can feel. There are some early warning signs as you are recovering from the injury to look for.

“In the first few weeks of recovery, pain with motion or stretch of the muscle starts to worsen and feels stiffer,” said Dave Smith, physical therapist with Marshfield Clinic Health System. “Instead of the initial swelling of the entire muscle, you will often times feel a smaller area of pain and stiffness the size of a marble up to the size of a small ball in larger muscles.”

Myositis ossificans happens when bony tissue forms by mistake as your body heals

By accidentally replacing muscle cells (fibroblasts), with the cells that help form bone (osteoblasts), the body creates a deposit of immature bone inside the muscle tissue. This gradually occurs about two to three weeks after the initial injury.

As the bony mass becomes larger, it may become palpable and painful. The mass can limit range of motion for the affected muscles. This can slow the healing process.​

There’s no sure-fire way to know whether ​​​​​​​​​​​​myositis ossificans will occur for you after a muscle injury.

Prompt response to the injury can help prevent a mass from forming:

  • The first 24 hours after a deep muscle bruise are critical to the long-term management of the injury. If you suffer this type of injury, you may need to remove yourself from the event to receive immediate medical attention.
  • Apply ice packs immediately after the injury occurs and during the next several days. Ice helps decrease swelling of muscle tissue and gives the tissue a better chance to heal.
  • Light stretching of the injured muscle is highly encouraged. However, stretching shouldn’t be painful. Continue activity and stretching so your range of motion doesn’t become limited. Myositis ossificans is more likely to develop in a sedentary muscle.​

Treatment for myositis ossificans tends to be conservative

Usually treatment begins with NSAID (non-steroidal anti-inflammatory drug) medication such as ibuprofen, which helps reduce swelling. Topical treatments, such as Biofreeze® or Icy Hot®, help reduce pain. You may continue to exercise or play with this injury. However, wearing protective padding can prevent additional trauma to the area that could cause the bony deposit to increase.

If the problem persists, treatment may include physical therapy for stretching and strengthening exercises to help decrease the size of the bony-tissue deposit. Physical therapists also may use a therapeutic ultra-sound machine to break up the bony growth. This makes it easier for the body to reabsorb the bony tissue and form healthy muscle tissue.

When the muscle first suffers a bruise or strain, it will often contract to allow healing and prevent re-injury. If kept in this shortened position too long, the muscle will lose flexibility. This can lead to further strain when returning to activities. “A physical therapist specializes in knowing when to progress with more dynamic stretching or progressive strengthening,” Smith said. We also can identify when in the recovery process more passive treatments like ice/heat, massage, light stretching and rest are more appropriate.”

Removing the bony deposit with surgery is rarely necessary. If the calcification is removed too early and before it’s mature (usually between six to 12 months), it’s highly likely the deposit will again form in the muscle. Surgery is considered if the deposit is causing excessive pain or compressing a nerve, or if it greatly interferes with your range of motion.​​​

Related posts

Common sports injuries: what to know about prevention and treatment

‘Injury-free’ is the name of the game in sports

Prep your body for exercise with dynamic warm-ups

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