myositis ossificans

Etiology

• trauma, especially skeletal muscle trauma
  • premature return to activity after an injury
• hereditary form

Pathology

• inflammatory myopathy
• extraskeletal calcification typically involving striated muscle & soft tissue

Genetics

• autosomal dominant (fibrodysplasia ossificans progressiva)

Clinical manifestations

• pain
• limitation of joint movement
• 80% of ossifications arise in the thigh or arm
• other sites of ossification include:
  • intercostal spaces, erector spinae, pectoralis muscles, gluteus maximus, gluteus minimus, chest
• pain & mass diminish with time

Diagnostic procedures

• ultrasonography (US)
  • calcification may be detected 2 weeks earlier on ultrasound than on radiography

Radiology

• hazy densities are sometimes noted ~ one month after injury
• denser opacities may appear two months after injury
• calcification fully matures in > 6 months after injury

Complications

• nerve compression

Differential diagnosis

• may be confused with sarcoma

Management

• rest
• immobilization
• physical therapy
• NSAIDs

More general terms

• muscular disease; myopathy

More specific terms

• fibrodysplasia ossificans progressiva