Lumbar Facet Joint Morphology and Degenerative Lumbar Spondylolisthesis: A Systematic Review and Meta-Analysis

Study Design Systematic review and meta-analysis. Objectives To evaluate the associations between lumbar facet orientation, facet tropism, and degenerative lumbar spondylolisthesis (DLS), while assessing sex-specific differences in facet morphology. Methods A PRISMA-compliant systematic review and meta-analysis was prospectively registered in PROSPERO (CRD420261417450). PubMed/MEDLINE, Embase, Scopus, Cochrane CENTRAL, and Web of Science were searched through June 2026. Studies evaluating lumbar facet morphology in adults with DLS were included. Random-effects meta-analyses using restricted maximum likelihood estimation and Hartung–Knapp adjustment were performed. Risk of bias and evidence certainty were assessed. Results Thirty-nine studies met the inclusion criteria. Sixteen studies (3,321 participants) were included in the facet orientation meta-analysis. Patients with DLS demonstrated more sagittally oriented facet joints than controls (SMD 1.30, 95% CI 0.78–1.82; p < 0.0001; I 2 = 97.2%). Nine studies (1,913 participants) showed greater continuous facet tropism in DLS patients (MD 2.72°, 95% CI 2.07°–3.38°; p < 0.0001; I 2 = 47.2%). Binary facet tropism was not statistically significant (OR 2.20, 95% CI 0.85–5.66; p = 0.0817). Sex-specific, severity, and instability data were insufficient for quantitative synthesis. Conclusion DLS is associated with more sagittally oriented facet joints and greater continuous facet tropism than controls. Limited sex-specific data and heterogeneity highlight the need for standardized measurement techniques and prospective longitudinal studies to clarify causality and sex-related effects.