Pyogenic sacroiliitis: diagnosis, management and clinical outcome.

Objective: The purpose of the present study was to evaluate the role of diagnostic tools and management options for patients with pyogenic sacroiliitis, including potential complications.
Materials and Methods: This retrospective study included 16 patients with pyogenic sacroiliitis who were admitted to a single orthopaedic centre between 2007 and 2012. The following data were collected: demographics, history, radiography, magnetic resonance images (MRI), biological data, type of pathogenic agent, abscess formation, type of management, and clinical outcome.
Results: Our study demonstrated that only one-fifth of the patients with lumbogluteal or hip pain had established diagnoses of suspected pyogenic sacroiliitis upon admission. MRIs confirmed this diagnosis in all cases. MRI examinations revealed joint fluid in the sacroiliac joint and significant oedema of the adjacent bone and soft tissues. In 12 of the 16 cases, erosions of the subchondral bone were encountered. Contrast-enhanced MRI revealed that 9 patients had abscesses. All patients received antibiotic therapy. Antibiotic treatment was only successful in 9 cases. The other 7 patients underwent computed tomography (CT)-guided abscess drainage. Drainage was sufficient for 4 patients, but 3 patients required open surgery. One patient required sacroiliac arthrodesis. The clinical outcomes included minimal disability (n = 10), moderate disability (n = 5), and full disability (n = 1) of the spine.
Conclusions: Contrast-enhanced MRI is mandatory for a reliable diagnosis. Abscess formation was observed in approximately half of the MRI-diagnosed sacroiliitis cases and required minimally invasive drainage under CT guidance or frequently open surgery.