Outcomes of lumbar fusion surgery in isthmic versus degenerative spondylolisthesis: A systematic review and meta-analysis

Lumbar spondylolisthesis can cause a significant disability due to back and lower extremity pain. Degenerative spondylolisthesis (DS) and isthmic spondylolisthesis (IS) are the two most common types. DS results from arthritic changes and degenerative disc disease, whereas IS occurs secondary to a pars interarticularis defect. This study compared surgical outcomes between IS and DS. A systematic literature review and meta-analysis was performed according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. Twenty studies comprising 3136 patients were included (DS: 1944; IS: 1192). No differences were identified in terms of estimated blood loss (mean difference [MD]: 5.79, 95% confidence interval [CI]: 42.88, 54.46; I 2 = 81.7%), length of stay (MD: 0.24, 95% CI: 1.38–0.90; I 2 = 87.7%), duration of operation (MD: 2.73, 95% CI: 20.61–15.16; I 2 = 84.7%), reduction of Visual Analog Scale (VAS) for back pain before and after surgery (MD: 0.01, 95% CI: 0.68–0.65; I 2 = 87.5%), reduction in Oswestry Disability Index before and after surgery (MD: 1.37, 95% CI: 2.39–5.12; I 2 = 75.5%), return to operating room for any reason (odds ratio [OR]: 1.01, 95% CI: 0.48–2.15; I 2 = 0%), successful fusion at the last follow-up (OR: 0.68, 95% CI: 0.26–1.77; I 2 = 60.5%), adjacent segment disease during follow-up (OR: 0.45, 95% CI: 0.18–1.13; I 2 = 0%), and subjective unsatisfactory outcome (OR: 1.53; 95% CI: 0.99–2.35; I 2 = 0%). IS was associated with significantly higher odds for reporting subjective unsatisfactory outcome compared to DS (OR: 1.56; 95% CI: 1.00–2.43, I 2 : 0%) in the subgroup analysis of posterior lumbar interbody fusion/transforaminal lumbar interbody fusion. DS showed greater VAS back pain reduction than IS with posterolateral fusion alone (MD: -1.06, 95% CI: -1.90–0.22, I 2 :0%). Surgical outcomes are largely comparable between IS and DS, though etiology-specific differences in patient-reported outcomes may depend on fusion technique.