Objective: The aim of our study is to determine the prevalence of sacral dysmorphism and to reveal the differences between dysmorphic sacrum and normal sacrum.

Material and Method: Two hundred seventy five patients were included in our study. Patients were analyzed for the presence of signs of sacral dysmorphism: mammillary body, dysmorphic neural foramen, tongue-in- groove morphology, residual sacral disc space. Measurements were made on the images: 1. sacral safe corridor width, 2. sacral safe corridor width, sacrum width, sacroiliac screw length for the distance between SIE-promontorium. The obtained data were evaluated by loading into the SPSS (ver:22,0) program.

Results: Of the patients, 165 (60%) were male and 110 (40%) were female, and the mean age of the patients was 60.33(19-99). Mamillary body was seen in 81 patients (29.5%), tongue-in- groove morphology in 31 patients (11.3%), dysmorphic neural foramen in 80 patients (29.1%), and residual sacral disc space in 164 patients (59.6%). The mean width of the 1st sacral safe corridor was 14.33 mm, the average width of the 2nd sacral safe corridor was 8.53 mm, the average width of the sacrum was 112.5 mm, and the mean distance between the sacroiliac joint-promontorium was 71.1 mm.

Conclusion: Sacral dysmorphism is quite common in society. In patients with sacral dysmorphism markers, 1st and 2nd sacral corridor widths are significantly narrower and iliosacral screw placement is more difficult. In these patients, due to the high probability of development of neurovascular complications during iliosacral screw placement, more care should be taken.