Pelvic infection as a cause of bilateral sacro-iliac arthritis and ankylosing spondylitis.

Abstract

About 30 years ago it became evident that bilateral sacro-iliac arthritis was a very frequent feature of ankylosing spondylitis. Since then, this finding has been repeatedly confirmed. It is now widely believed by rheumatologists and radiologists that the diagnosis of ankylosing spondylitis cannot be substantiated unless there is radiological evidence of sacro-iliac arthritis. Particularly significant is the fact that this sacro-iliac joint involvement is almost invariably the first radiological manifestation of the disease. Moreover, after the initial years of the development of ankylosing spondylitis, both sacro-iliac joints are always involved to an approximately equal degree. So constant has been the occurrence of bilateral sacro-iliac arthritis, that there has now developed a general belief among clinicians and radiologists that bilateral non-pyogenic sacro-iliitis is synonymous with the diagnosis of ankylosing spondylitis. There are however several other pathological conditions in which these joints undergo slow destruction, and a review of these reveals that a feature common to them is infection situated within the pelvic cavity. Considerable evidence has now accumulated that patients with ankylosing spondylitis also frequently have a focus of chronic pelvic sepsis. It is thought, therefore, that this infection may be a provocative aetiological factor in the production of bilateral sacro-iliac arthritis. It is suggested that, in patients with the necessary genetic and constitutional makeup, this sacro-iliac arthritis may herald the onset of the full syndrome of ankylosing spondylitis with spinal and peripheral involvement.