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. Although the study fell short of producing a prediction rule, it has again reviewed for the reader the current limitations of previous studies and clarifies what we as surgeons should provide in the consent process for patients who may desire surgical treatment. We are still left with questions regarding the long-term impact of nonsurgical treatment and the ultimate benefit of surgical treatment in those patients that may possess adverse risk factors for poorer outcomes.
The article by Leven et al5 attempts to explain the risk factors for reoperation in patients treated for symptomatic disk herniation. The authors present data, which seems logical, that younger patients, possibly because of activity levels, are at increased risk of reherniation. However, the findings that the presence of an asymmetric neurologic deficit may be protective are somewhat unclear. The overall reoperation rate of 15% is important information for the surgeon's informed consent process. Again the reader is left with more questions regarding other common questions on risk factors for reherniation, which were not answered in the article study design such as specific activity levels and anatomic features such as disk space height and facet angle.
The study by D’Oro et al6 provides data regarding the incidence of symptomatic degenerative disk disease after a traumatic thoracolumbar spinal fracture. The authors appear to state the obvious that fractures involving the thoracic spine treated surgically demonstrate less degenerative disease at follow up compared with surgically managed lumbar fractures. One would expect anatomic regions allowing more motion to be biomechanically effected to a greater degree by a motion limiting procedure. Unfortunately, the design of this study relying on CPT and ICD-9 codes is subject to obvious limitations of administrative registry miscoding, which invalidates any of the study's findings. Probably a more important question in this population is the influence of specific spinal pelvic spatial orientation on junctional disease, especially in patients treated nonoperatively. This would require evaluation of an extremely large number of patients followed prospectively over time after trauma. Unfortunately, this data was not available with this study.
Finally, the study by Lenke et al7 evaluating the risk of neurologic deterioration after complex surgical intervention in the setting of adult spinal deformity is very important for the spinal community to appreciate and especially patients who are considering surgical intervention. It is not uncommon for postsurgical deformity patients to demonstrate less motor function in the perioperative period often attributed to medications and lack of effort caused by pain. Rarely such neurologic worsening may be significant enough to warrant further imaging studies and at times surgical reintervention. This study clearly shows that a large percentage of neurologically intact patients—that is, 22% may worsen after surgical intervention in this setting. These deficits may be present at 6 weeks and 6 months after surgery. Fortunately the vast majority of these cases are transient and a large percentage will regain their strength by 6 months. Again, the reader is left with more questions about which specific patients are at increased risk for neurologic loss especially in routine osteotomy procedures. Ongoing surveillance in this patient population is necessary to further aid in the shared decision making process between surgeon and patient.
The articles that were selected in this edition were meant to convey that scientific investigation not only add to our fundamental knowledge but also raise more questions and will hopefully stimulate further research in these clinically challenging domains. Despite Level One evidence from relatively high-quality studies, we are still not fully equipped to adequately inform our patients and know with any certainty that we are choosing the right surgical procedure.
1. Ghogawala Z, Dziura J, Butler WE, et al. Laminectomy plus fusion versus laminectomy alone for lumbar spondylolisthesis. New Engl J Med
2. Forsth P, Olafsson G, Carlsson T, et al. A randomized, controlled trial of fusion surgery for lumbar spinal stenosis. New Engl J Med
3. Simmonds AM, Rampersaud YR, Dvorak MF, et al. Defining the inherent stability of degenerative spondylolisthesis: a systematic review. J Neurosurg Spine
4. Tetreault L, Kopjar B, Cote P, et al. A clinical prediction rule for functional outcomes in patients undergoing surgery for degenerative cervical myelopathy: analysis of an international prospective multicenter data set of 757 subjects. J Bone Joint Surg Am
5. Leven D, Passias PG, Errico TJ, et al. Risk factors for reoperation in patients treated surgically for intervertebral disc herniation: a subanalysis of eight-year SPORT data. J Bone Joint Surg Am
6. D’Oro A, Spoonamore MJ, Cohen JR, et al. Effects of fusion and conservative treatment on disc degeneration and rate of subsequent surgery after thoracolumbar fracture. J Neurosurg Spine
7. Lenke LG, Fehlings MG, Shaffrey CI, et al. Neurologic outcomes of complex adult deformity surgery. Results of the prospective, multicenter Scoli-RISK-1 study. Spine