Stability of the lumbar spine and method of instrumentation.

We have carried out a biomechanical study to investigate the effect on flexion, extension, and rotation of seven systems of fixation on five cadaveric lumbar spines. Pedicle fixation proved the most effective method to restrict these movements. Facet screw fixation was also successful. Harrington distraction rods, the Hartshill rectangle and the Luque technique, although restricting slight flexion and extension, exerted little control over rotation. We conclude that pedicular fixation and facet joint fixation provide the greatest overall stability and might, therefore, be the best systems to consider for multilevel fusions in the lumbosacral region.