Biomechanical Evaluation of Lumbosacral Reconstruction Techniques for Spondylolisthesis

Abstract

Iliac screw constructs reduced lumbosacral flexibility levels in three of four loading methods (axial rotation, flexion-extension, and lateral bending) compared with pedicle screw reconstructions. The addition of interbody cages decreased lumbosacral motion for the iliac screw treatments under flexion-extension loading and pedicle screw constructs under axial rotation but did not protect the sacral screws in destructive testing as the iliac screws did. Based on evaluation using an porcine model, both iliac screws and interbody cages effectively reduce the multidirectional flexibility properties of the lumbosacral junction; however, iliac screws are more restrictive of motion (at the lumbosacral joint) and protective of the S1 screws.