Abstract
Heterotopic ossification is the deposition of new bone around a joint. Its greatest clinical importance is the potential loss of joint range. Usually, it occurs in patients with head injury, spinal cord injury, burns, or direct trauma to muscle tissue. This is a case report of a 38-year-old patient with myasthenia gravis who developed limited range of motion of hips and the presence of new bone around bilateral hips confirmed with radiography and computerized tomography. This is the first report of myasthenia gravis with heterotopic ossification. This clinic presentation may be due to prolonged complete immobilization and/or mechanic ventilation as a result of muscle paralysis.