A computed tomography (CT) based morphometric study of superior pubic ramus anatomy among Arabs to determine safe intramedullary pubic rami screw insertion.

Abstract

To assess the morphometric variables of the superior pubic ramus in an Arab/ Middle Eastern population to establish a safe pubic screw fixation technique. Cross-sectional retrospective analysis of computed tomography (CT) pelvic images. Morphometric data were extracted including; on pubic ramus length, insertion angles, potential danger zones and ramus diameters. The correlation between pubic rami diameter and patient demographics was also analyzed. A total of 231 participants were included (45% female). The mean pubic ramus length was 104mm in females and 127mm in males. The narrowest canal diameters at the para-symphyseal area were; 7.35mm (males) and 4.75mm (females). The mediolateral insertion angle was 49.4° in females and 41.8° in males. The cephalic-caudal angle was 49.9° in males and 42.1° in females. The mean distance from the lateral ilium entry point to the joint articular surface was 23.5mm in males and 19.9mm in females. The symphysis pubis to tubercle exit point was higher in females than males (24.2mm vs 16.6mm, respectively). There was a significant positive correlation between age and pubic ramus diameters in all age groups. The results from this study suggest that percutaneous pubic rami screw fixation using the standard 6.5 or 7.3mm cannulated screw system may potentially be unsafe in female Arab patients. This subset of patients may require alternative non-cannulated screws (3.5-4.5mm) or plate options. Further, female patients may have a higher risk of acetabular joint penetration, while males have a potentially higher risk of pudendal nerve injury.