Radiological and Clinical Outcomes of Expansive LLIF cages – Single- arm and comparative systematic revision with metanalysis

Purpose Expandable cages have been introduced in lateral lumbar interbody fusion (LLIF) to enhance segmental lordosis correction and reduce endplate damage and subsidence risk. However, evidence regarding their efficacy remains inconsistent. This systematic review and meta-analysis aimed to evaluate the ability of expandable cages to promote segmental lordosis and assess their safety profile, specifically regarding subsidence and complications, compared to static cages. Methods A systematic search of PubMed, Google Scholar, Ovid, and BVS databases was conducted following PRISMA guidelines. Inclusion criteria were original studies using expandable cages in LLIF, reporting on segmental lordosis and/or subsidence. Quality was assessed using the Newcastle–Ottawa Scale. Random-effects meta-analyses with cluster-robust variance estimation and subgroup/meta-regression analyses were performed using R software. Results Nine studies with a total of 414 patients (expandable group) were included. The pooled mean segmental lordosis at last follow-up in the expandable cage group was 8.67° (95% CI: 5.34–11.9°), with no significant influence from preoperative lordosis. When compared to static cages, the mean difference in lordosis was not statistically significant (MD = − 2.56°, p = 0.27). Subsidence rate for expandable cages was 4% (95% CI: 1–15%). A significant reduction in odds of subsidence was observed with expandable cages versus static cages (OR = 0.16; 95% CI: 0.02–0.99, p = 0.049). Overall complication data were inconsistently reported and not pooled. Conclusion Expandable cages in LLIF are associated with low subsidence rates and achieve substantial segmental lordosis correction, although superiority over static cages in lordosis gain remains unproven. These findings support their use for individualized anatomic correction; however, more high-quality, prospective studies are needed to validate their clinical advantages and long-term outcomes.