Orthopaedic management of ankylosing spondylitis.

Ankylosing spondylitis is an inflammatory disease of unknown etiology that affects an estimated 350,000 persons in the United States and 600,000 in Europe, primarily Caucasian males in the second through fourth decades of life. Worldwide, the prevalence is 0.9%. Genetic linkage to HLA-B27 has been established. Ankylosing spondylitis primarily affects the axial skeleton and is characterized by inflammation and fusion of the sacroiliac joints, spine, and hips. The resultant deformity leads to severe functional impairment in approximately 30% of patients. Orthopaedic management primarily involves correction of hip deformity through total hip arthroplasty and, less frequently, correction of spinal deformity with spine osteotomy. Closing wedge osteotomies have the lowest incidence of complications. Whether patients with ankylosing spondylitis are at increased risk for heterotopic ossification remains controversial, but comparison with age- and sex-matched counterparts suggests no dramatically higher risk. Because of the high rate of missed fractures and complications after minor trauma in patients with ankylosing spondylitis, plain radiographs are usually not sufficient for evaluation. Thorough patient assessment should include a comprehensive history, physical examination, and laboratory studies.