Outcome of decompression with and without fusion in spinal stenosis with degenerative spondylolisthesis in relation to preoperative pain pattern: a register study of 1,624 patients

Background contextPatients with spinal stenosis with concomitant degenerative spondylolisthesis (DS) and predominant back pain (PBP) have been shown to have inferior outcome after surgery. Studies comparing outcome according to preoperative pain predominance and treatment received are lacking.PurposeThe purpose was to study if adding spinal fusion to the decompression in DS affects outcome in patients with PBP (back pain [BP] Visual Analog Scale [VAS] more than or equal to leg pain [LP] VAS) compared with predominant leg pain (PLP) (BP VAS less than LP VAS).Patient sampleThe Swedish Spine Register was used and included 1,624 patients operated for DS at the L4–L5 level.Outcome measuresSelf-reported measures were used, including a VAS for BP and LP, the EuroQol-5D (EQ-5D), and the physical and mental component summaries of the Short-Form 36 to estimate health-related quality of life and the Oswestry disability index (ODI) to estimate function.MethodsInclusion criterion was single-level DS operated on with either decompression only (D) or decompression and instrumented posterolateral fusion (DF). Based on preoperative LP and BP scores, the patients were assigned to one of the two groups: LP predominance or BP predominance. The patients completed the outcome protocol at 1- and 2-year follow-ups. Statistical analysis was performed using linear regression adjusting for multiple potential confounders.ResultsIn the adjusted outcome at the 1-year follow-up, patients with PLP reported a 7.9-mm more improvement on the VAS for BP with fusion, compared with D (95% confidence interval [CI], 0.7–15.2), p=.03. Despite more change in the fused group, the reported BP levels remained similar in the D versus decompressed and fused at the 1-year follow-up (28 vs. 24, p=.77). The patients with PBP benefited from adding fusion in terms of BP 7.1 (95% CI, 0.3–13.9, p=.04), LP 8.8 (2–15.7, p=.01), the ODI 5.7 (1.6–9.9, p=.006), and the EQ-5D 0.09 (1.7–0.02, p=.02) at the 1-year follow-up as the DF group reported greater change in the outcome compared with the D group. At the 2-year follow-up, no significant differences were found between D and decompressed and fused in either the LP or the PBP groups.ConclusionsPatients with PBP operated with DF report better outcomes in terms of pain, function, and health-related quality of life than patients with D. Although these differences are significant on a group level, they may fail to reach minimal clinical significant difference. Patients with PLP report significantly more improvement in terms of BP with DF compared with D, but because of baseline differences in preoperative BP, these improvements may not be explained by the added fusion per se. At the 2-year follow-up, no significant differences were observed between the D and DF patients in either the PBP or PLP groups, but greater loss to follow-up in the DF groups could potentially bias these findings.