Ankylosing spondylitis and its variants. A review of recent developments for orthopedic surgeons

Recent developments in genetic tissue typing have altered concepts of ankylosing spondylitis (AS) or variants of this spondylitic arthritis. It is now apparent that AS is separate and distinct from rheumatoid arthritis; and the term "rheumatoid" should be avoided except as it applies to the latter, usually characterized by rheumatoid factor or nodules and symmetrical arthritis of peripheral joints. Classical definitions of AS require X-ray evidence of sacroiliitis and/or restriction of chest expansion. Recent studies suggest that many patients, especially women, may have symptoms of AS without typical roentgenographic or clinical findings. Use of the HL-A B27 genetic test is useful for identifying AS patients. Radioisotope bone or joint scanning techniques further augment present diagnostic capabilities. Atypical AS may be a very common form of morbidity among patients with back pain in the United States. Since patients have a tendency to form osseous reankylosis after total hip replacement, it is especially important for orthopedic surgeons to identify incipient AS and related disorders. Inappropriate treatment or procedures may be avoided by use of these newer clinical tools in the evaluation of patients with chronic back or skeletal pain.