Adjustable Lordotic Expandable Spacers: How Do They Compare to Traditional Static Spacers in Lateral Lumbar Interbody Fusion?

Abstract

Introduction: Expandable interbody spacers with adjustable lordosis were designed to expand in situ and avoid complications such as endplate damage, excessive trialing and forceful impaction associated with static spacers. This study compares the clinical and radiographic two-year outcomes between patients treated with static or expandable interbody spacers with adjustable lordosis for Minimally Invasive Lateral Lumbar Interbody Fusion (MIS LLIF). Methods: This is a retrospective, multi-site, multi-surgeon, Institutional Review Board-exempt chart review of patients who underwent MIS LLIF using either a static (27 patients) or expandable spacer with adjustable lordosis (66 patients). Radiographs, complications and patient-reported outcomes were collected and compared from preoperative up to 24-month postoperative follow-up. Results: Mean improvement of Visual Analogue Scale back pain at 6, 12 and 24 months, as well as Oswestry Disability Index scores at 3, 6, 12, and 24 months, were significantly higher in the expandable group compared to the static group. The mean improvement of ODI scores from preoperative to 3, 6, 12, and 24 months was significantly greater in the expandable group by 55.6%, 75.6%, 77.4%, and 108.9% and by 48.2%, 34.6%, and 71.5% at 6, 12, and 24 months postoperatively for VAS pain scores, compared to the static group and (p<0.05) Disc height mean improvement from preoperative to 24 months was more significant in the static group compared to the expandable group. Implant subsidence was significantly greater in the static group (18.5%, 5/27 patients) compared to the expandable group (0/66 patients) (all p<0.05). Conclusion: This study showed significant positive clinical and radiographic outcomes for patients who underwent MIS LLIF using static or expandable interbody spacers with adjustable lordosis. Both static and expandable groups demonstrated long-term maintenance of significant radiographic improvements, with minimal complications reported and sustained significant clinical improvements at 24-month follow-up. There was a 0% subsidence rate in the expandable group, compared to an 18.5% subsidence rate in the static group. The use of expandable spacers with adjustable lordosis was safe and effective for the studied patient population.