MANUAL MINORS
Myositis ossificans is a condition where muscle and connective tissue turn into bone (ossification) following trauma, such as a contusion or muscle tear. It most commonly affects large muscles in the limbs, like the quadriceps or arm muscles, and is characterised by bone formation in areas that were previously only soft tissue. This process is painful and can limit mobility in the affected area.
Diagnosis
Diagnosis is based on a history of prior trauma, followed by persistent pain, swelling, and restricted movement in the affected area. Over time, a bone mass may become palpable. X-rays reveal bone formation within the muscle approximately 3-4 weeks after the injury. Ultrasound and magnetic resonance imaging (MRI) are useful in early stages to identify inflammation and soft tissue changes.
Differential Diagnosis
Condition | Key Difference |
|---|---|
Osteosarcoma | Malignant bone tumour with more aggressive growth, unrelated to prior trauma. |
Intramuscular haematoma | Painful post-traumatic mass, but no bone formation on X-rays. |
Cellulitis | Soft tissue infection without bone formation or trauma history. |
Muscular fibrosis | Muscle stiffness, but without radiological evidence of ossification. |
Emergency Management
In the emergency setting, initial management includes pain relief with analgesics and nonsteroidal anti-inflammatory drugs (NSAIDs). The affected area should be temporarily immobilised, and early surgical intervention should be avoided, as premature manipulation may worsen ossification. Early referral to orthopaedics for appropriate management and long-term follow-up is important.
Definitive Treatment
Definitive treatment is primarily conservative. It involves physiotherapy to maintain range of motion and prevent joint stiffness, although exercise should be moderate to avoid aggravating ossification. Long-term NSAID use may help control inflammation.
Surgery to remove the ectopic bone is considered only if ossification is extensive, causing severe functional limitation or persistent pain. Surgery is generally delayed until the ectopic bone has matured, which can take 6 to 12 months.
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