Objectives: The purpose of this study was to evaluate the biomechanical stability of a modified triangular osteosynthesis construct with S1 pedicle screws compared with other described lumbopelvic fixation constructs in a U-type sacral fracture model.
Methods: U-type sacral fractures were created in validated fourth-generation spinopelvic models. Four different constructs were cyclically loaded with displacement measured in all planes: (1) bilateral L5 pedicle screws with rods attached to iliac bolts, (2) bilateral L5 and S1 pedicle screws with rods attached to iliac bolts, (3) bilateral L5 pedicle screws with rods attached to iliac bolts with a transsacral-transiliac screw, and (4) bilateral L5 and S1 pedicle screws with rods attached to iliac bolts with a transsacral-transiliac screw.