The term $quot;myositis ossificans$quot; encompasses four categories of clinicopathological disorders. The first, myositis ossificans progressive(fibrodysplasia ossificans progressive), is a rare genetic disease characterized by progressive heterotopic ossification involving skeletal muscle, tendon, ligaments, and fascia, with congenital malformation of the great toes, and usually microdactyly, monophalangism, and malformed proximal phalanges, with valgus deformity of metatarsophalangeal joint. The ossification begins shortly after birth and may contribute to the patient`s death. The second, heterotopic ossificans, can occur in patients with neuromuscular and chronic diseases such as paraplegia, poliomyelitis, polymyositis, bum, tetanus, and infection. But the lesions in these cases often lack the typical histologic features of myositis ossificans. The third, myositis ossificans traumatica, is the most common; it develops in response to soft tissue trauma such as a single severe injury, minor repetitive injures, fracture, joint dislocation, stab wound, or surgical incision. The forth, nontraumatic myositis ossiticans, also designated :pseudomalignant osseous tumors of extraskeletal soft tissues$quot; and $quot;psedomalignant myositis ossificans$quot;, occurs in persons repeated small mechanical injures or nonmechanical soft tissue injuries due to local ischemia, inflammation, or other factors cannot be ruled out in such cases.