Traumatic heterotopic ossification of the quadratus lumborum: a case report.

Heterotopic ossification is the process of pathologic bone formation in soft-tissue structures that usually do not form bone. This pathologic process may occur in tissue such as skin, subcutaneous tissue, skeletal muscle and periarticular tissue.1 It was reported in the literature as early as 1740, and is frequently reported in modern literature.2 Two forms of heterotopic ossification are commonly described. The post-traumatic form is localized, whereas the systemic form occurs in fibrodysplasia ossificans progressiva.