[The effect of pedicle screw instrumentation on posterolateral spinal fusion. A prospective, randomized study with a two-year follow-up].

The aim was to evaluate the effect of supplementary pedicle screw fixation (Cotrel-Dubousset [CD]) in posterolateral lumbar spinal fusion. The study comprises 130 patients undergoing lumbar or lumbosacral fusion for spondyloisthesis grades I-II or degenerative segmental instability conditions. The patients were randomly allocated for no instrumentation (n = 66) or CD instrumentation (n = 64) in posterolateral lumbar fusion.