Comparison of 1-Year Clinical and Radiographic Outcomes Between 2 Expandable Cage Designs in Navigation-Assisted Minimally Invasive Transforaminal Lumbar Interbody Fusion

<h3>Background</h3> Minimally invasive transforaminal lumbar interbody fusion (MIS-TLIF) often struggles to provide sufficient lordotic alignment restoration. The choice of cage design, including its height and lordotic angle, is critical. This study compares 2 expandable cage designs in MIS-TLIF: one that increases only disc height (group H) and another that expands both height and lordosis (group HL). <h3>Methods</h3> Seventy-five patients who underwent navigation-assisted MIS-TLIF using expandable cages were reviewed. These included 35 cases using expandable cages that increase only height (group H) and 40 cases using cages that expand both height and lordosis (group HL). Clinical outcomes, including a numeric rating scale of back pain, leg pain, and Oswestry Disability Index and radiographic parameters, including disc height, lordotic angle, subsidence, and fusion rates, were evaluated. <h3>Results</h3> Both groups showed significant improvements in clinical outcomes, with no differences between groups. Postoperative disc and foraminal height increased significantly. At the 1-year follow-up, group HL demonstrated greater improvements in segmental lordosis (4.0° ± 3.3° vs 1.9° ± 5.4°, <i>P</i> = 0.018) and disc angle (5.8° ± 4.1° vs 1.9° ± 4.2°, <i>P</i> &lt; 0.001) compared with group H. The overall fusion rate was 92%, and the overall subsidence rate was 32%, which decreased to 20% after the first 20 cases. No neurological injuries occurred, and there were no significant differences in complications between the groups. <h3>Conclusion</h3> This study demonstrates that MIS-TLIF with expandable cages designed to increase lordosis offers superior improvement in segmental lordosis at the 1-year follow-up, compared with expandable cages that only expand disc height. Both cage designs achieved high fusion rates and showed similar clinical outcomes. <h3>Clinical Relevance</h3> The surgeon’s experience in the use of expandable cages is a critical factor in reducing the risk of cage subsidence, a complication that may adversely affect clinical outcomes. <h3>Level of Evidence</h3> 3.