Pelvic antropometric measurement in 3D CT for placement of two unilateral iliosacral S1 - 7.3 mm screws

PURPOSE: Stability of the dorsal pelvic ring is important for patient mobilisation and can be restored using several surgical procedures after fracture. Placement of percutaneous iliosacral screws is a reliable and minimal-invasive technique to achieve stabilisation of the dorsal pelvic ring by placement of two screws in the first sacral vertebra. Aim of this study was to evaluate 3D CT scans regarding the anatomical possibility to place two 7.3 mm iliosacral screws for fixation of the dorsal pelvic ring. METHODS: 3D CT datasets of 500 consecutive trauma patients with 1000 hemipelves of a mid-european level I trauma centre with or without pelvic injury were evaluated and measured bilaterally in this retrospective study. RESULTS: One thousand hemipelvic datasets of 500 patients (157 females, 343 males) with a mean age of 49.7 years (18 to 95) were included in this study. Only 16 hemipelves (1.6%, 11 in females, 5 in males) in 14 patients (2.8%, 9 females = 5.73%, 5 males = 1.5%) showed too narrow corridors so that 7.3 mm screw placement would not be possible (p = 0.001). In women, too narrow corridors occurred 3.9 times as often as in men. Only two females showed this bilaterally. CONCLUSION: The evaluation of 3D CT scans of the pelvis showed the importance of planning iliosacral screw placement, especially if two 7.3 mm screws are intended to be placed in the first sacral vertebra.