What is myositis ossificans?

From the Guidelines

Myositis ossificans should be managed with a focus on reducing inflammation and pain, using the RICE protocol and non-steroidal anti-inflammatory drugs (NSAIDs) like ibuprofen or naproxen, as there is no direct evidence from the provided studies to guide its treatment. The provided study 1 discusses fibrodysplasia ossificans progressiva (FOP), a severely disabling heritable disorder of connective tissue characterized by progressive heterotopic ossification, which is distinct from myositis ossificans. Key aspects of myositis ossificans management include:

• Rest, ice, compression, and elevation (RICE protocol) for the first 24-48 hours after injury
• Non-steroidal anti-inflammatory drugs (NSAIDs) like ibuprofen (400-800mg three times daily) or naproxen (500mg twice daily) for 1-2 weeks
• Gentle stretching and progressive physical therapy after the acute phase to maintain range of motion and prevent stiffness
• Avoiding aggressive massage, heat application, or forceful manipulation of the affected area Most cases of myositis ossificans resolve spontaneously within 6-12 months, but surgical removal may be considered for persistent cases that cause significant pain or functional limitations, although this is not directly supported by the provided evidence 1. The condition develops through an inflammatory response to trauma, where mesenchymal cells differentiate into bone-forming cells, creating calcification within the muscle, highlighting the importance of early recognition and appropriate management to prevent complications and optimize recovery.

From the Research

Definition and Characteristics of Myositis Ossificans

• Myositis ossificans is a fairly common disorder that typically involves progressive heterotropic bone formation 2.
• It is a self-limiting, benign ossifying lesion that can affect any type of soft tissue, including subcutaneous fat, tendons, and nerves 3.
• Myositis ossificans can be categorized into nonhereditary and hereditary types, with the latter being a distinct entity with a separate pathophysiology and treatment approach 3.

Etiology and Clinical Presentation

• The etiology of myositis ossificans is variable, but clinical presentation generally is characterized by an ossifying soft-tissue mass 3.
• Most cases are posttraumatically related, with the brachialis and quadricep femoris muscles frequently involved, especially in sport injuries 2, 4.
• Patients present with localized pain and swelling with loss of range of motion 4.

Diagnosis and Imaging

• Advanced cross-sectional imaging alone can be nonspecific and may appear to be similar to more sinister etiologies 3.
• The evaluation of a suspicious soft-tissue mass often necessitates multiple imaging modalities for accurate diagnosis 3.
• Plain radiographs may not be able to detect early lesions, which allows for an expanded role of ultrasonography as an early screening modality 4.
• Magnetic resonance imaging remains the gold standard for imaging of soft tissue masses 4.

Treatment and Management

• The treatment of myositis ossificans is complex and is often made in a multidisciplinary fashion because accurate diagnosis is fundamental to a successful outcome 3.
• Conservative treatment is implemented for most patients with excellent outcomes, with surgical excision being an option for persistent symptoms or progressive disease 4.
• Glucocorticoid in high doses is still the first-line treatment of patients with myositis, and combining pharmacological treatment with individualized and supervised exercise can be recommended based on evidence 5, 6.
• Immunosuppressive treatment in combination with exercise is recommended for patients with myositis to reduce disease activity and improve muscle performance 5.