Myositis ossificans is an uncommon complication after a muscle tear or acute trauma, where bone forms within the muscle, causing pain and swelling. So what is myositis ossificans, how does it happen, and how do we treat it?
What is myositis ossificans?
In myositis ossificans, bone forms in a muscle after acute trauma — such as a direct blow (a “dead leg”) — or, less often, an overuse injury like a muscle tear. It usually affects sportspeople, and is more common in contact sports.
The thigh muscles are most often affected, although other muscle groups, such as the calves or forearms, can be involved. Only about 5–10% of muscle injuries develop myositis ossificans. Certain patterns even have their own names — “rider’s bone” in the inner-thigh (adductor) muscles of horse riders, and “shooter’s bone” in the shoulder (deltoid) muscle.
Why does the bone form?
Honestly, we don’t fully know. After a significant muscle bruise, a collection of blood (a haematoma) forms, and in some people, the body lays down bone in the healing tissue instead of normal muscle. Returning to hard activity too soon and deep massage of a fresh contusion appear to increase the risk.
Symptoms of myositis ossificans
Myositis ossificans usually follows a significant muscle injury — most often a thigh contusion. The typical picture is a muscle injury that doesn’t settle as expected:
- Persistent pain and swelling weeks after the original injury
- Increasing stiffness and a loss of movement (for example, difficulty bending the knee when the thigh is involved)
- A firm, tender lump within the muscle
- Difficulty with weight-bearing when the quadriceps are affected
How is myositis ossificans diagnosed?
We suspect myositis ossificans when a muscle injury fails to improve or worsens beyond the expected recovery time. Imaging confirms it:
- X-ray — may be normal in the first few weeks, then shows the maturing bone. Over months, mature myositis ossificans has a characteristic pattern, with bone forming at the outside of the lump first.
- Ultrasound and MRI — helpful early, showing the muscle injury and the developing ossification.
Importantly, early myositis ossificans can occasionally look like a bone tumour on scans. The pattern of bone formation and the history of a preceding injury help distinguish this benign condition from more serious causes, which is why it should be assessed by a doctor experienced in muscle injuries rather than left to heal at home.
Treatment of myositis ossificans
Most cases settle with conservative treatment. In fact, the priority early on is to prevent it after a significant muscle contusion.
Prevention after a muscle contusion — the “NO HARM” principle
After a significant dead leg or muscle bruise, we follow the NO HARM principle: no heat, no alcohol, no running, and no deep massage — all of which can increase bleeding and the risk of myositis ossificans. Early compression and ice packs reduce bleeding and lower the risk, and the muscle is gently rested in a comfortable position.
Treating established myositis ossificans
- Relative rest and gentle movement — early rehabilitation is gentle. Aggressive stretching or strengthening too soon can worsen the condition, so the range of movement is rebuilt gradually.
- Anti-inflammatory medication — NSAIDs such as ibuprofen — helps with pain and may reduce ongoing bone formation. They’re usually avoided in the first couple of days after the injury (when they can increase bleeding), then used for a short period.
- Shockwave therapy — emerging evidence suggests that focused shockwave may help, and case reports in athletes describe good recovery of pain and movement.
- Progressive rehabilitation — once settled, a graded programme restores flexibility, strength, and sport-specific fitness.
Surgery
Surgery is rarely needed. Where a mature lump causes persistent pain or restricts movement, it can be removed — but only after the bone has fully matured (usually 6–12 months), as operating too early increases the risk of it returning.
Frequently asked questions about myositis ossificans
How long does myositis ossificans take to heal?
Most people recover within several weeks to a few months with conservative treatment, though the bone itself continues to mature for 6–12 months. Many lumps shrink over time, and most athletes return to sport once pain and movement have recovered.
Is myositis ossificans a tumour or cancer?
No — it’s a benign (non-cancerous) bone formation in muscle after an injury. The reason to take it seriously is that, in its early stages, it can look like a bone tumour on scans, so it needs a proper assessment to confirm the diagnosis. The history of a preceding injury and the pattern of bone formation reliably distinguish it from more serious causes.
Can you massage myositis ossificans?
No — deep or vigorous massage of a fresh muscle contusion can increase bleeding and make myositis ossificans more likely, and massaging an established lump can aggravate it. Avoiding deep massage is part of the “NO HARM” approach after a significant muscle injury.
How do you prevent myositis ossificans after a dead leg?
Follow the NO HARM principle — no heat, no alcohol, no running, and no deep massage — and apply compression and ice early to limit bleeding. Rest the muscle gently and avoid rushing back to sport, as returning too soon is a key risk factor.
Does myositis ossificans need surgery?
Rarely. The great majority settle with conservative treatment. Surgery is reserved for a mature lump that keeps causing pain or restricting movement, and is only done once the bone has fully matured, to reduce the chance of it returning.
Final word from Sport Doctor London about myositis ossificans
Myositis ossificans is an uncommon but important complication of a muscle injury, most often in the thigh after a contusion. The best treatment is prevention — sensible early management of a significant muscle bruise. Where it does develop, most cases settle with gentle, progressive rehabilitation, and surgery is rarely needed.
If a muscle injury isn’t recovering as expected, Dr Masci can assess you in London, including an ultrasound in the clinic. Contact the team here or call +44 (0) 203 488 0350.
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