Static versus Expandable Interbody Fusion Devices: A Comparison of 1-Year Clinical and Radiographic Outcomes in Minimally Invasive Transforaminal Lumbar Interbody Fusion

Abstract

To compare the radiographic and clinical outcomes of static versus expandable interbody cages in transforaminal lumbar interbody fusion using minimally invasive surgery (MIS-TLIF). Overview of Literature: Expandable interbody cages may potentially improve radiographic and clinical outcomes following MIS-TLIF compared to static pages, but at a potentially higher cost and increased rates of subsidence. Methods: A retrospective chart review of 1-and 2-level MIS-TLIFs performed from 2014 to 2020 was reviewed. Radiographic measurements were obtained preoperatively, 6 weeks postoperatively, and at final follow-up. Patient-reported outcome measures (PROMs) including the Oswestry Disability Index, Visual Analog Scale (VAS) back, and VAS leg were evaluated. Multivariate linear regression analysis determined the effect of cage type on the change in PROMs, controlling for demographic characteristics. Alpha was set at 0.05. Results: A total of 221 patients underwent MIS-TLIF including 136 static and 85 expandable cages. Expandable cages had significantly greater anterior (static: 11.41 mm vs. expandable: 13.11 mm, p<0.001) and posterior disk heights (static: 7.22 mm vs. expandable: 8.11 mm, p<0.001) at 1-year follow-up. Expandable cages offered similar improvements in segmental lordosis at 6 weeks (static: 1.69° vs. expandable: 2.81°, p=0.243), but segmental lordosis was better maintained with expandable cages leading to significant differences at 1-year follow-up (static: 0.86° vs. expandable: 2.45°, p=0.001). No significant differences were noted in total complication (static: 12.5% vs. expandable: 16.5%, p=0.191) or cage subsidence rates (static: 19.7% vs. expandable: 22.4%, p=0.502) groups at 1-year follow-up. Conclusions: Expandable devices provide greater improvements in radiographic measurements including anterior disk height, posterior disk height, and segmental lordosis, but this did not lead to significant improvements in PROMs, complication rates, subsidence rates, or subsidence distance.

Intradiscal Osteotomy and Bilateral Expandable Transforaminal Interbody Fusion Cages for Iatrogenic Kyphotic Deformity: A Technical Report

“…There are conflicting reports in the literature regarding the degree to which expandable TLIF cages can add segmental lordosis, but many studies have reaffirmed their ability to increase both disc and foraminal height. [3][4][5][6][7] The vast majority of this evidence comes from surgeons using minimally invasive techniques or treating 1 to 2 level degenerative pathology. Some surgeons argue that the insertion of a collapsed interbody spacer reduces the damage to the endplates, while other surgeons argue that the powerful expansion mechanisms can damage the endplates themselves.…”

Correction of Spinal Sagittal Alignment after Posterior Lumbar Decompression: Does Severity of Central Canal Stenosis Matter?

“…In terms of radiological outcomes, expandable cages can achieve superior disc height increments and SL restoration in lumbar fusion patients compared to static cages. [120][121][122][123][124]126,127]. However, a meta-analysis focusing on the radiological outcomes of TLIF revealed no statistically significant differences in the spinal sagittal alignment (SL and LL) or pelvic parameters [127].…”

“…From the radiological perspective, the use of expandable cages in lumbar fusion has yielded promising results. Expandable cages have been reported to yield superior disc height increments and SL restorations in lumbar fusion patients compared with static cages [120][121][122][123][124]. Research indicates that these cages effectively maintain or improve the SL and disc height, which are critical factors in achieving optimal spinal alignment and biomechanics after surgery.…”

Innovative Developments in Lumbar Interbody Cage Materials and Design: A Comprehensive Narrative Review

“…Radiologically, the use of expandable cages in lumbar fusion has yielded promising results. Expandable cages have been reported to yield superior disk height increments and SL restorations in patients who had undergone lumbar fusion compared with static cages [ 120 – 124 ]. A study indicated that these cages effectively maintain or improve SL and disk height, which are critical factors in achieving optimal spinal alignment and biomechanics after surgery.…”

“…Regarding radiological outcomes, expandable cages can achieve superior disk height increments and SL restoration in patients who had undergone lumbar fusion compared with static cages [ 120 – 124 , 126 , 127 ]. However, a meta-analysis on the radiological outcomes of TLIF revealed no statistically significant differences in spinal sagittal alignment (SL and LL) or pelvic parameters [ 127 ].…”