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Effects of Spinal Instrumentation on Fusion of the Lumbosacral Spine

Study Design This study retrospectively reviewed the effects of pedicle screw fixation on lumbosacral fusion for degenerative conditions. The records and radiographs of a group of patients treated by wide decompression and fusion of the lumbosacral spine and by one surgeon were studied. Two treatment groups were identified by fusion technique; one group received autologous bone graft only, and a second group was treated by autologous bone grafting supplemented with pedicle screw fixation. Objectives The two study groups were compared to determine the effects of pedicle screw fixation on lumbosacral fusion for degenerative conditions after wide decompression. Summary of Background Data The reported success rate of lumbar and lumbosacral fusion in the literature is variable. Although several studies have reported high fusion rates with internal fixation, few controlled studies have been published. A critical review of isolated lumbosacral fusions (for degenerative conditions) and the effects of instrumentation is necessary to determine the effectiveness and complications associated with pedicle screw systems in this setting. Methods This study reviewed 215 consecutive patients operated on from 1987 to 1992 for degenerative conditions of the lumbosacral spine. Group 1 included 126 patients who underwent autogenous posterolateral bone graft after decompression. Group 2 included 89 patients treated with Edwards instrumentation and autogenous bone graft. Fusion status was determined via radiographs. Clinical results were based on pain relief after a minimum 2-year follow-up period. Results In Group 1, an overall fusion rate of 65% was obtained. Clinically, 56% had good or excellent results. Complications included pseudarthroses (35%), dural tears (3.2%), and infection (2.4%). In Group 2, a fusion rato of 91% was achieved. In this group, 89% had a good or excellent clinical result. Complications included pseudarthroses (9%), dural tears (2.2%), and infection (2.2%). Conclusions Use of pedicle screw and rod fixation with the Edwards system led to significantly improved results in lumbosacral fusions over autogenous bone graft alone, with a lower complication rate. The use of spinal instrumentation is a valuable adjunct to achieve lumbosacral fusion in patients who have undergone decompressive surgery for the spine.