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Lumbar spinal stenosis: indications for arthrodesis and spinal instrumentation.

Surgical indications for simple decompression in patients with lumbar spinal stenosis are well established. Following these guidelines, surgeons can expect good and excellent outcomes in 75% to 90% of patients. Despite the publication of many studies pertaining to the addition of arthrodesis and instrumentation, the indications for adding these procedures to a decompression are much less clear. Preoperative and intraoperative factors must be carefully considered when contemplating the addition of arthrodesis in the setting of spinal stenosis. In patients with preoperative degenerative spondylolisthesis, scoliosis, or kyphosis, and those in whom stenosis develops at a previously decompressed segment, serious consideration should be givenfor inclusion of an arthrodesis. Fusion should also be considered for those patients with stenosis adjacent to a previously fused lumbar segment. Excision of a significant portion of the facet joints or radical excision of the intervertebral disk during the course of the decompression predispose the patient to postoperative instability. The addition of an arthrodesis will likely benefit these patients. Relative indications for the use of spinal instrumentation in the setting of spinal stenosis include correction of deformity, recurrent spinal stenosis with instability, degenerative spondylolisthesis, adjacent segment stenosis with instability, and multiple level fusions.