1489. Assessing the Difference in Clinical and Radiological Outcomes between Expandable Cage and Non-Expandable Cage among Patients undergoing MIS-TLIF: A Systematic Review and Meta-Analysis

Authors: Mohamad Bydon, MD, FAANS ; Mohammed Ali Alvi, MD; Shyam Kurian, BS; Waseem Wahood, MS; Anshit Goyal, MD; Yagiz Yolcu, MD; F.M. Moinuddin, PhD; Benjamin Elder, MD, PhD (Rochester, MN)

Introduction:

Minimally Invasive Transforaminal Interbody Fusion (MIS-TLIF) has been shown to have excellent outcomes for surgical management of degenerative disc disease and other pathologies. However, one disadvantage of the technique is the challenge in addressing coronal imbalance and restoring lumbar lordosis and sagittal alignment. Use of expandable cages in MIS-TLIF has been hypothesized to circumvent this disadvantage. Literature comparing the clinical and radiological outcomes of expandable cages and non-expandable cages in MIS-TLIF is sparse.

Methods:

Preferred Reporting Items for Systematic Reviews and Meta-Analysis (PRISMA) guidelines were used to conduct a systematic review and meta-analysis to compare the clinical and radiological outcomes of expandable cages and non-expandable cages in patients undergoing MIS-TLIF.

Results:

A total of 12 studies (706 patients) were included in the meta-analysis. The mean increase in disc height was found to be significantly greater for non-expandable cages group than for expandable cages group (1.33mm, 95% CI:1.28-1.38 vs 1.14 mm,95% CI:1.06-1.23;p <0.001). We did not detect any significant difference in change in lumbar lordosis at last follow up between the two groups (non-expandable: 2.55, 95% CI: 2.22-2.88 vs expandable: 2.27, 95% CI:1.80-2.75, p=0.34). The mean change in segmental lordosis was found to be significantly higher for expandable cage group (5.04degrees,95% CI:3.89-6.20 vs 2.08degrees,95%CI:1.93-2.22, p<0.001). Finally, we did not detect any significant difference in fusion rate (expandable: OR0.75, 95%CI:0.44-1.06 vs non-expandable 0.90,95% CI:0.86-0.95;p=0.33), subsidence rate (expandable:0.05,95%CI 0.00-0.09;non-expandable 0.08,95%CI:0.01-0.15,p=0.41) or in reoperations (expandable:0.02,95%CI:0.01-0.04 vs non-expandable: 0.01,95% CI:0.00-002,p=0.56) at last follow up between the two groups.

Conclusion:

Our results indicate that there may not be a significant difference in clinical and radiological parameters between expandable cages and non-expandable cages among patients undergoing MIS-TLIF, and it is unclear if the higher cost of the expandable cages is justified.