Does Preoperative Degenerative Spondylolisthesis Worsen Outcome in Degenerative Lumbar Spinal Stenosis? A Swiss Prospective Multicenter Cohort Study

Aim: The aim of our study was to compare clinical outcomes and examined the effect of simple decompression without additional fusion in patients with preoperative degenerative spondylolisthesis (DS) versus patients without preoperative degenerative spondylolisthesis (non-DS) on one or two adjacent levels.

Methods: For this retrospective analysis we did use data from the Lumbar Stenosis Outcome Study (LSOS). The LSOS is conducted as a prospective cohort study at eight medical centers in Switzerland. The main outcomes of this study were change in SSM symptoms, SSM function, and EQ-5D-EL sum score over time. These outcomes were measured at baseline, six, and 12-month follow-up. To obtain an unbiased effect of DS versus non-DS we chose matching techniques relying on propensity scores.

Results: For this study, 853 potentially eligible patients agreed to participate between December 2010 and December 2015. Of these, 350 patients underwent decompression alone surgery within the first six months after baseline. Out of these, 133 patients met the inclusion criteria, with accompanying DS (n = 32) or without DS (n = 101). The estimated effects of DS versus non-DS for change in SSM symptoms from baseline to 6 and 12 months were 0.08 (95% CI −0.34 to 0.49) and 0.16 (−0.23 to 0.55), respectively. For change in SSM function, the estimated effects were −0.01 (−0.39 to 0.37), and 0.08 (−0.33 to 0.50). Changes in between group difference of EQ-5D-EL sum score were estimated to be −7.19 (−15.24 to 0.86) and −4.88 (−13.29 to 3.54) from baseline to 6 and 12 months. None of the group differences between the non-DS and the DS group were statistically significant. All matched patients improved over time in all secondary outcomes.

Conclusion: Among the patients with degenerative lumbar spinal stenosis our study demonstrates that in the two groups, degenerative spondylolisthesis and non-degenerative spondylolisthesis, patients distinctively take advantage of simple decompression without fusion. Our results indicate that the presents of a preoperative degenerative spondylolisthesis does not worsen outcome in comparison to non-olisthesis cases when treated by simple decompression. Conversely, our results could indicate that adding fusion in preoperative olisthesis cases might only be reserved for certain patients.