Myositis ossificans is an uncommon complication after a muscle tear or acute trauma. Generally, bone forms in the muscle after a muscle injury, causing pain and swelling. So, what is myositis ossificans, how does it happen, and how do we treat it?
What is myositis ossificans?
In this condition, bone forms in the muscle after acute trauma to the muscle or overuse injury, such as a muscle tear. Usually, this condition forms in sportspeople and is more common in contact sports. Generally, thigh muscles are most often affected, although other muscle groups, such as the calves or forearm muscles, can be affected. Only about 5-10% of muscle injuries develop myositis ossificans.
Causes
We don’t know the answer to that question. Most practitioners think the cells known as fibroblasts get confused and start laying down bone rather than scar tissue after a significant injury. The more severe the damage, the more likely it is that bone will form in muscle. Also, failure to treat the injury adequately, such as using anti-inflammatory measures, increases the risk.
Diagnosis
Generally, bone formation starts about 2-4 weeks after a muscle injury and can last up to 6 months.
Clinical features include:
- A history of trauma or muscle strain, usually in the last 2-4 weeks
- Aching pain in the muscle that is worse with muscle contraction
- Night and morning pain
- Swelling or a lump in the muscle that feels ‘woody.’
- Restricted movement of the joints above and below the muscle
Myositis ossificans radiology
We perform tests to confirm a diagnosis.
Usually, the initial test is either an X-ray or an ultrasound. These tests will show bone formation within the affected muscle. When tests show bone formation, the concern is that it could be a tumour. Thankfully, there are differences between these two conditions that make the diagnosis more precise. We use other CT scans or MRI tests when the diagnosis is unclear. Occasionally, a muscle biopsy is needed when the diagnosis is still uncertain.
Myositis ossificans treatment
Once recognised, we suggest reducing training or sport. Next, we try simple treatments to reduce inflammation. These treatments include rest, ice, compression, and anti-inflammatory medication. Gentle stretching is allowed, but you should avoid deep massage. As symptoms improve, you can move into protected strengthening (isometrics) followed by more intensive (isotonic) exercises.
Also, anti-inflammatory medication such as ibuprofen, diclofenac, or indomethacin can reduce inflammation and allow the body to break down and resorb the bone slowly.
Overall, most cases settle with simple treatment. However, in some patients, symptoms such as pain, swelling, and reduced movement fail to resolve. Sometimes, the bone mass presses on surrounding structures such as joints, nerves, or vessels. In these cases, we consider surgical excision. However, there are risks to excision. One real risk is the recurrence of bone if excision is performed too early, before the bone matures.
Frequently asked questions about myositis ossificans
Lump in the quad muscle: Could it be myositis ossificans?
Overall, lumps can be due to other disorders, such as abnormal growths or tumours. A history of injury or trauma is essential, but other possibilities need to be considered if there is no history of trauma.
Does myositis ossificans go away?
Yes, in most cases, myositis ossificans goes away with protected loading and simple treatments, as outlined above. Generally, this process of bone breakdown takes weeks to a few months.
How do we prevent myositis ossificans?
Generally, the risk of myositis ossificans increases with a more severe contusion. In addition, poor treatment or aggressive treatment with heat or massage also increases the risk of developing myositis ossificans. We recommend the NO HARM principle: no heat, no alcohol, no running, and no deep massage. Better treatment with compression and ice packs reduces bleeding and lowers the risk. Also, we think compression of the contusion with ice and the knee in a fully flexed position is better.
Final word from Sportdoctorlondon about myositis ossificans
Myositis ossificans is a complication of direct trauma, causing a dead leg or haematoma. Most cases are resolved with simple treatment and do not need medical intervention. The key is to get a correct diagnosis.
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