Prevalence of Sacral Dysmorphia of Patients in Rajavithi Hospital, A Retrospective Study

Abstract

Background: Sacral dysmorphia entails abnormal anatomy of the upper sacrum. Dysmorphic sacra have narrow and angled upper osseous corridors, increasing the risk of cortical perforation during iliosacral screw and transacral screw insertion. To date, no statistical data regarding this condition exist in Thailand. We aimed to collect statistical data for this patient group in Thailand. Objective: To determine the prevalence of sacral dysmorphia among patients at Rajavithi Hospital. Methods: Data were collected from Rajavithi Hospital’s database for the past 5 years, from January 1, 2016, to December 31, 2020, and analyzed to determine the prevalence of sacral dysmorphia and safe corridors for percutaneous screw fixation at the sacrum. Results: A total of 594 patient records were collected. Sacral dysmorphia was found in 136 cases, accounting for 23%. Gender was found to have no effect on disease prevalence but did affect sacral size, with males being significantly larger. The sacral dysmorphia group had 94.1% unable to insert a transacral screw at position S1, with an average width and height of 15.46 and 17.00 mm, respectively. At position S2, both iliosacral and transacral screws of all sizes (6.5, 7.0, and 7.3 mm) could be inserted, with average width and height of 13.98 and 17.84 mm, respectively. Conclusion: We recommend using the S2 position instead of the S1 position for percutaneous screw fixation in individuals with sacral dysmorphia due to advantages including safety, low complication rates, ease of surgery, and strength.