Standalone lateral and oblique approaches vs traditional posterior approaches for adjacent segment disease: A systematic review and meta-analysis

Background Standalone cages have been introduced as a treatment option for ASD; however, the evidence regarding their effectiveness remains mixed. We conducted a systematic review to compare surgical and clinical outcomes of patients with lumbar ASD who underwent management with lateral or oblique standalone cages vs a posterior approach. Methods PubMed, Scopus, and Embase were searched for articles published through January 1, 2026 using terms including ASD, anterior lumbar interbody fusion, lateral lumbar interbody fusion, oblique lumbar interbody fusion, transforaminal lumbar interbody fusion, and posterior lumbar interbody fusion. Complications, radiographic parameters, and patient-reported outcomes were analyzed using a fixed-effects model when I² was <50%; a random-effects model was used for instances of high heterogeneity. Results Eight studies (281 patients) were included. The standalone group had significantly lower estimated blood loss (mean difference [MD]:-311.66 ml, (95% CI:-351.61, −271.72) p < 0.001), shorter operative time (MD:-85.14 min, (95% CI:-105.97, −64.32) p < 0.001), and reduced hospital stay (MD:-3.23 days, (95%CI: −4.65,-1.80) p < 0.001) than the posterior group. Additionally, there was a significantly greater change in disc height (MD:1.6 mm, (95% CI: 0.67, 2.68) p = 0.001) and lower complication odds (odds ratio [OR] = 0.38, 95% CI: (0.17, 0.88) p = 0.02) in the standalone group. However, there was a higher subsidence odds during follow up (OR = 4.65, 95% CI: (1.24, 17.37) p = 0.02) in that group. Conclusion Standalone cages were a viable option for lumbar ASD treatment, offering similar radiological and clinical outcomes to posterior approaches with fewer complications. However, informing patients about the higher risk of cage subsidence associated with standalone cages is essential.