Early Experience With Uniplanar Versus Biplanar Expandable Interbody Fusion Devices in Single-Level Minimally Invasive Transforaminal Lumbar Interbody Fusion

Objective: To compare the early radiographic and clinical outcomes of expandable unipla-nar versus biplanar interbody cages used for single-level minimally invasive transforaminal lumbar interbody fusion (MIS-TLIF).Methods: A retrospective review of 1-level MIS-TLIFs performed with uniplanar and bipla-nar polyetheretherketone cages was performed. Radiographic measurements were performed on radiographs taken preoperatively, at 6-week follow-up, and 1-year follow-up. Oswestry Disability Index (ODI) and visual analogue scale (VAS) for back and leg at 3-month and 1-year follow-up.Results: A total of 93 patients (41 uniplanar, 52 biplanar) were included. Both cage types provided significant postoperative improvements in anterior disc height, posterior disc hei-ght, and segmental lordosis at 1 year. No significant differences in cage subsidence rates were found between uniplanar (21. 9%) and biplanar devices (32. 7%) at 6 weeks (odds ra-tio, 2.015; 95% confidence interval, 0.651-6.235 ; p = 0.249) with no additional instances of subsidence at 1 year. No significant differences in the magnitude of improvements based on ODI, VAS back, or VAS leg at 3-month or 1-year follow-up between groups and the proportion of patients achieving the minimal clinically important difference in ODI, VAS back, or VAS leg at 1 year were not statistically significantly different (p > 0.05). Finally, there were no significant differences in complication rates (p = 0.283), 90-day readmission rates (p =1.00), revision surgical procedures (p = 0.423), or fusion rates at 1 year (p = 0.457) between groups.Conclusion: Biplanar and uniplanar expandable cages offer a safe and effective means of improving anterior disc height, posterior disc height, segmental lordosis, and patient -re-ported outcome measures at 1 year postoperatively. No significant differences in radiograph-ic outcomes, subsidence rates, mean subsidence distance, 1-year patient-reported outcomes, and postoperative complications were noted between groups.