[Clinical and imaging characteristics of 110 patients with infectious sacroiliitis]

Objective: To investigate the clinical and imaging characteristics of infectious sacroiliitis. Methods: A total of 110 patients diagnosed with infectious sacroiliitis were retrospectively analyzed between 2008 and 2017.Clinical manifestations and therapeutic responses, laboratory tests such as HLA-B(27), erythrocyte sedimentation rate (ESR), C reactive protein (CRP), T cell spot test for tuberculosis infection(TB-SPOT), Brucella agglutination test ect., blood culture of pathogens, pathological findings as well as magnetic resonance imaging were all recorded and analyzed. Results: Among the 110 patients, the male to female ratio was 44 to 66 with an average age 15-58(29.4±10.8) years and the course of disease 0.3-60 (5.7±13.2) months. As to the pathogens, 71 cases were pyogenic, 24 cases with tuberculous sacroiliitis, and 15 cases were brucellosis infections. The majority of patients (97.3%) had unilateral sacroiliac joint involvement. Ten (9.1%) patients suffered infectious sacroiliac arthritis after delivery. Hip pain was the main clinical manifestation (83/110,75.5%) and fever as the second (77/110,70.0%). HLA-B(27) was positive in 11 patients (10.0%). Both ESR and CRP were elevated in the majority. There were 103 patients receiving sacroiliac joint puncture biopsy. Seven patients were diagnosed through blood culture or brucellosis agglutination test. Bone marrow edema and osteolytic lesions in magnetic resonance imaging (MRI) were more common in pyogenic or tuberculous sacroiliitis than in brucellosis infections. Conclusion: Infectious sacroiliitis should be differentiated from spondyloarthritis, which develops more in female patients, with short disease duration and fever, mostlynegative HLA-B(27). The majority patients present unilateral sacroiliitis. Active inflammatory lesions are usually beyond sacroiliac joints with osteolytic changes in MRI examinations.