Bringing Clarity to the Treatment of Common Spinal Disorders
A staple surgical procedure for the degenerative lumbar spine surgeon is the surgical management of symptomatic lumbar neurogenic claudication with or without spondylolisthesis. The consensus of the spinal community after years of debate is the relative efficacy of fusion when a decompression is performed in the setting the implied instability of a lumbar spondylolisthesis. The New England Journal of Medicine recently revived this debate through the publication of two well-designed studies evaluating this question. The study by Ghogawala et al1 evaluated 138 patients screened for symptomatic lumbar stenosis and spondylolisthesis. After randomization, 35 patients underwent decompression and 31 patients underwent decompression and fusion. Patients with slips greater than 3 mm were excluded from the study and the majority of patients were enrolled from one institution. The authors found that patients who underwent fusion had an initial higher acute complication rate but the reoperation rate was significantly higher in the nonfusion group. Readers of this article would therefore conclude that a fusion was an appropriate adjunct if a decompression is considered in this setting. These findings are in direct contrast to the prospective randomized study by Forsth et al2 on patients surgically treated with lumbar stenosis with or without spondylolisthesis. A total of 247 patients were enrolled of which 123 were assigned to decompression and 124 to decompression and fusion. In this study, specific nonsurgical measures and surgical procedures were left to the discretion of the operating surgeons facilitating generalizability. These authors found no significant difference in reoperation rates or postoperative resource utilization between both groups; although the patients in the fusion group had longer hospital stays and incurred a greater mean operating cost. These authors at over 6-year follow up found no significant difference between the mean ODI scores and found no significant advantage to the adjunct of a fusion procedure in the setting of spondylolisthesis.
Readers are now left to make sense of these of two well-performed clinical studies. The criticism of the Forsth et al2 study is the relative disregard for patient-specific anatomy, essentially the degree of instability at the spondylolithesis level. The presence of what the authors define as “stable verse unstable slips” were treated all equally in the randomization processes and with “instability” a likely confounder it should probably have been controlled for; although randomization may well have done so. In contrast, the study by Ghogawala et al1 excluded patients with greater than 3 mm of motion on flexion-extension x-rays or mechanical back pain, thus controlled for stability and showed a difference. The spinal community may be coming to a consensus that determining stability in spondylolisthesis will dictate the surgical procedure3; however, even for relatively stable spondylolisthesis deformities, Ghogawala's data showed a 34% revision rate with no fusion. Possibly the differences in these two studies rest on basic confounders of cultural, regional, and socioeconomic differences that may exist between the study locations in terms of surgeon and patient preference and specific surgical methods. This may account for the high rate of reoperation in the fusion group reported by Forsth et al2 group (22%) compared with that reported by Ghogawala et al1 (14%). The readers are left with high quality results to apply to their practice, but a more detailed investigation into patient-specific factors may be necessary to develop more robust conclusions about the optimum method of surgical management for patients with a symptomatic degenerative spondylolisthesis.
The study by Tetreault et al4 evaluating a potential clinical prediction rule for functional outcomes in patients undergoing surgery for degenerative cervical myelopathy adds further to our understanding of prognostic indicators for patients who undergo surgery for this spinal abnormality.