Prevalence and Patterns of Sacral Dysmorphism Amongpatients Presenting to Kenyatta National Hospital: Implications on Sacral Iliac Screw Insertion

Abstract

Study background Use of percutaneous sacral iliac screws is the current gold standard for the fixation of posterior pelvic ring injuries, unfortunately in up to 15 percent of cases screw misplacement occur leading to neurovascular complications. This is directly correlated with the orientation and size of safe corridors of fixation in dysmorphic sacra. This study was conceived as a result of the challenges that orthopedic surgeons face when fixing posterior pelvic wall disruptions via percutaneous sacral iliac screws. The study aimed to raise the index of suspicion for sacral dysmorphism and to enhance the level of pre-operative preparedness for the orthopaedic surgeon when placing percutaneous sacral iliac screws. Broad objective: To evaluate qualitative and quantitative characteristics of sacral dysmorphism as well as the prevalence of sacral dysmorphism in Kenya. Study design and site: This was a cross-sectional study carried out at the Radiology Department, Kenyatta National Hospital. Participants and Methods: It involved radiographic evaluation of 303 stored abdominal pelvic computerized tomography (CT) scans of persons aged 18-70 years for the study period March 2020to March 2021. The evaluation was carried out on CT scans that met the inclusion and exclusion criterion. The data collected included qualitative features of sacral dysmorphism found on reviewed images as well as objective measurements of sacral dysmorphism. These objective measurements included sacral dysmorphism score, and safe zone cross-sectional area. Lastly data on acetabular version angles was collected to evaluate for any correlation with sacral dysmorphism. Data Management and Analysis: Data was collected using Kobo Collect®; this is a mobile application on Android® phones. The dataset underwent univariate analysis using Stata 14 ® to determine proportions, tables, charts and graphs .A regression analysis was conducted to establish any correlation between acetabular version and sacral dysmorphism. Results: The most prevalent feature of sacral dysmorphism was lack of recession of the S1 segment at 82% followed by presence of unfused sacral segment at 77%. The 12 remaining features of sacral dysmorphism were distributed in only one third of the population There was no significant gender difference noted (p=0.078). A sacral dysmorphism score of more than 70% was found to be in 63% of the population. The average cross-sectional area of the S1 segment was found to be 370mm2 for females and 417mm2 for males. An average acetabular angle of 14 degrees. Gender variation was noted in males presenting with a higher sacral dysmorphism score. Conclusion, Further studies are needed to further describe sacral dysmorphism in the African pelvis. Our study has pointed to multiple areas in which further research can be done