Biomechanical comparison of sacroiliac screw techniques for unstable pelvic ring fractures

Objective: To determine the stiffness and strength of various sacroiliac screw fixations to compare different sacroiliac screw techniques. Design: Randomized comparative study oil embalmed human pelvises. Materials and Methods: In 12 specimens, we created a symphysiolysis and sacral fractures oil both sides. Each of these 24 sacral fractures was fixed with 1 of the following methods: 1 sacroiliac screw in the vertebral body of S1,2 screws convergingly in S1. or 1 screw in S1 and 1 in S2. Oil the left and right side of a pelvis, different techniques were used. The pubic symphysis was not stabilized. We measured the translation and rotation stiffness of the fixations and the load to failure using a 3-dimensional video system. Results: The stiffness of the intact posterior pelvic ring was superior to any screw technique. Significant differences were found for the load to failure and rotation stiffness between the techniques with 2 screws and a single screw in S1. The techniques utilizing 2 screws showed no differences. Conclusions: Based on the results of this Study, we can conclude that a second sacroiliac screw in Completely unstable pelvic fractures increases rotation stiffness and improves the load to failure.