Surgical Treatment of Adjacent Segment Degeneration after Spinal Fusion in Degenerative Lumbar Disc Disease

ABSTRACT

OBJECTIVE: We experienced some cases of adjacent segment degeneration after spinal fusion and treated them by various reoperation methods. The authors report an evaluation of causes of adjacent segment degeneration after spinal fusion and treatment methods. METHODS: Sixteen patients was admitted to our hospital due to adjacent segment degeneration after spinal fusion from November 1997 to May 2001 and we operated 11 patients among 16 patients with various surgical methods. We analyzed clinical diagnosea, surgical methods, and disc degeneration status of adjacent segment following spinal fusion on 1st operation and 2nd operation, and also evaluated the clinical symptoms, type of adjacent segment degeneration, and time interval between the 1st operation and the 2nd operation. RESULTS: Clinical diagnoses on 1st operation were degenerative spondylolisthesis of four cases, chronic degenerative disc disease with spinal stenosis of six cases, and recurred herniated lumbar disc disease of one case. We treated eight cases by posterior lumbar interbody fusion, one case by 360degrees fusion, and two cases by pedicle screw fixation only. Disc degeneration on adjacent segment to spinal fusion existed already in nine among 11 patients before spinal fusion. Types of adjacent segment degeneration after spinal fusion were disc degeneration of two cases, lumbar instability of three cases, lumbar stenosis of four cases, and lumbar instability and stenosis of two cases. Most patients complained of low back pain due to disc degeneration and instability, and some patients complained of leg and buttock pain due to stenosis. Time interval from 1st operation to reoperation was 20 months through 99 months, mean time interval was 57 months. CONCLUSION: Inevitable compensatory mechanism occurs at adjacent segment after fusion, because of stress concentration and alteration of biomechanics after fusion. But, we achieve excellent or good results of reoperation surgical treatment for adjacent segment degeneration after spinal fusion.