Myositis ossificans (heterotopic ossification) is a benign, heterotopic ossification of soft tissue and/or skeletal muscle that either occurs congenitally or, more commonly, following soft tissue or muscle injury

• Etiology
  • Posttraumatic: especially after implantation of an artificial hip joint or after blunt muscle trauma
• Clinical features: localized symptoms in the affected muscle/tissue (e.g., quadriceps femoris muscle, brachialis muscle)
  • Restriction of movement
  • Muscle stiffness
  • Pain, swelling
  • Palpable soft tissue mass
• Diagnostics
  • Soft tissue ossification is detectable on conventional x-ray.
  • Radiological findings: periosteal reaction with periarticular soft tissue calcifications (eggshell calcification)
  • Laboratory findings: ↑ alkaline phosphatase and ESR levels