Pyogenic infection of the sacroiliac joint. Case reports and review of the literature.

Three cases of pyogenic sacroiliitis are described, and the English literature from 1878 to 1990 reviewed, for a total of 166 cases. In 1 patient the source of infection was identified at the site of an intravenous line; 1 patient had 2 risk factors for developing the disease (pregnancy and intravenous drug use); and a third patient had no source of infection and no associated risk factors. The diagnosis of pyogenic sacroiliitis was made in each patient by history, physical examination, and positive skeletal scintigraphy or computed tomography of the sacroiliac joint. The infectious agent causing septic arthritis was identified by fine-needle aspiration of the sacroiliac joint under fluoroscopic guidance. Two of the 3 patients also had an open biopsy of the sacroiliac joint--one to confirm the organism causing septic arthritis, and the other for surgical drainage of the infected sacroiliac joint. Cultures from all 3 patients grew organisms uncommon for this disease, and all were treated for 6 weeks with intravenous antibiotics. In all patients pain diminished after treatment. Pyogenic sacroiliitis is a relatively rare condition (1-2 cases reported/year) that may be clinically difficult to diagnose unless the clinician is familiar with the disease. A prompt diagnosis can prevent significant morbidity and reduce serious complication. Major predisposing factors include intravenous drug use, trauma, or an identifiable focus of infection elsewhere, but 44% of patients have no predisposing or associated factors identified. Most patients present with an acute febrile illness with pain in the buttocks and pain on movement that stresses the affected sacroiliac joint. There is no specific blood test which points to the diagnosis of pyogenic sacroiliitis, although the erythrocyte sedimentation rate may be greater than 100 mm/hr. The diagnostic procedure of choice is bone scan with attention to the early perfusion phase, which usually localizes the affected sacroiliac joint. Unilateral involvement is the rule. In patients whose blood cultures fail to reveal a causative organism, fluoroscopic guided fine-needle aspiration of the sacroiliac joint under general anesthesia may help to identify the organism. If all cultures are negative, open biopsy of the sacroiliac joint may be required. Open biopsy should also be done if sequestration or an abscess is formed, or if the patient fails to respond to antibiotic therapy.(ABSTRACT TRUNCATED AT 400 WORDS)