ABSTRACT
PURPOSE: To identify, describe, and compare the prevalence of sacroiliac joint anatomical variants. METHODS: A retrospective study was performed on computed tomography scans. Joint space was measured, and variants were classified as accessory joint, ileosacral complex, bipartite bony plate, semicircular defect, iliac bony plate, and ossification centers. RESULTS: 400 scans were analyzed. Mean age was 49 years, 180 men (45%), and 220 women (55%). 209 (52.2%) patients presented an anatomical variant with higher prevalence in women (65.4% vs 36.2%), and those older than 40 years of age (60% vs 40%). Mean joint space was similar bilaterally (right 2.41 ± 0.65 mm vs. left 2.37 ± 0.65 mm). Prevalence was: 19.8% accessory joint, 6.5% ileosacral complex, 12.3% bipartite bony plate, 8% semicircular defect, 5% iliac bony plate, and 0.8% for ossification centers. CONCLUSION: Prevalence of anatomical variants of the SIJ is higher in the Hispanic population, women, and those older than 40 years.