Ct based morphometric analysis of sacro-iliac joint in south indian demography

Background: Various disease processes can affect the sacroiliac joint (SIJ) altering its joint anatomy causing low back ache. The information obtained from physical examination of SIJ is often not adequate and the use of the radiological imaging methods gains importance for the diagnosis of SIJ diseases. Objective: The main objective of this study was to measure the articular space width of SIJ, in-order to ascertain its normal size and to probe the anatomic variations of SIJ in relation to age and sex of the patient, within south Indian population using Computed Tomography (CT). Materials and methods: A retrospective cross-sectional radiological study was performed utilizing 3mm abdominal & pelvic CT slices acquired from 301 patients (197 males; 104 females) without sacroiliac complaint, who had undergone scanning for other unrelated pathology. Result: The overall mean SIJ space width measured was 2.63±0.78 mm. The mean joint space width for males and females were 2.54±0.67 mm and 2.79±0.93 mm respectively. In adults below 40 years, the measured width was 2.71±0.89 mm and in older patients it was 2.66±0.77 mm. 130 (43.2%) individuals had uniform SIJ and remaining 171 (56.8%) showed non-uniformity. Five anatomical variations were observed; accessory SIJ (9 patients, 3%), iliosacral complex (26 patients, 8%), semicircular defect (23 patients, 7%), ossification centers (9 patients, 3%) and crescentic defect (2 patients, 1%). Conclusion: This study has helped us determine the normal SIJ space width existing in South Indian population and determine the frequency of observed anatomic variants. The data acquired through this study, along with its inferences can help in various pathological correlations.