title: Heterotopic ossification and pseudoarthrosis in the shoulder following encephalitis. A case report and review of the literature.
abstract: Heterotopic bone formation, or myositis ossificans, is common, particularly following trauma, total hip arthroplasty, spinal cord injury, severe head injury, and long-term coma. Although the mechanism is unknown, the pathogenesis is assumed to depend on transformation of mesenchymal cells to bone forming cells in response to a variety of stimuli. The clinical findings, laboratory data, roentgenograms, and radionuclide studies are standard aids in the diagnosis of heterotopic ossification. The treatment usually consists of range-of-motion exercise, nonsteroidal antiinflammatory drugs, X-ray therapy, disodium etidronate (EHDP), and excisional surgery. Reported here is a rare case of periarticular heterotopic ossification in the shoulder of a 38-year-old woman following head injury and 13 months in a coma. The unusual feature was the development of a pseudoarthrosis within the heterotopic bone. The patient's shoulder became markedly stiff with the development of a heterotopic pseudoarthrosis. Excision of the heterotopic bone and pseudoarthrosis was performed to improve the range of motion. Clinical roentgenographic, radionuclide, and pathologic observations are presented on the formation of a synovial joint within the heterotopic bone.
mesh_terms: D000328:Adult; D003131:Combined Modality Therapy; D004660:Encephalitis / Q000150:complications*; D005260:Female; D006801:Humans; D009999:Ossification, Heterotopic / Q000150:complications / Q000209:etiology*; D011542:Pseudarthrosis / Q000000981:diagnostic imaging / Q000209:etiology* / Q000628:therapy; D011859:Radiography; D012782:Shoulder