1517. Comparative Effectiveness of Expandable versus Static Lateral Lumbar Interbody Fusion Devices: Two Year Clinical and Radiographic Outcomes

Authors: Richard F Frisch; Torrey Shirk, BA; Jessica Riggleman, BS; Ingrid Luna, MS; Daina Brooks, BS; Gita Joshua, MA; Charles Ledonio, MD (Mt Pleasant, SC)

Introduction: Minimally invasive (MIS) lateral lumbar interbody fusion (LLIF) procedures using large interbody static spacers may require excessive trialing and forceful impaction, leading to iatrogenic endplate disruption, excessive neural retraction, and implant subsidence. The in situ expansion capability offered by expandable interbody spacers facilitates insertion to help reduce endplate damage and optimize endplate contact. This study reported radiographic and clinical outcomes of static and expandable interbody spacers following MIS LLIF, and device-related complications including implant subsidence. Methods: This study included 48 patients with degenerative disc disease who underwent MIS LLIF at 1-2 contiguous level(s) using a polyether-ether-ketone static or titanium expandable intervertebral spacer. Twenty-one patients were treated with static spacers, and 27 with expandable spacers. All spacers had supplemental posterior stabilization. Clinical and radiographic outcomes were analyzed at 12 and 24 months postoperatively. Results: Mean patient age was 66.6±9.7 years, 72.9% of patients were female. No significant differences were observed between static and expandable groups in operative time (64.0±39.2min,73.7±39.7min), estimated blood loss (35.6±29.2cc,40.0±30.8cc), or length of hospital stay (2.0±1.3days, 2.4±1.3days), respectively (p<0.05). Mean VAS pain and ODI, and RAND 36 scores improved significantly (p<0.05) at 24-month follow-up. Patients treated with expandable implants were found to have significantly lower scores for VAS back pain (n=39,1.3±1.7,3.8±3.0,p<0.05) VAS leg pain (n=40,1.4±2.3,3.6±3.6,p<0.05), and ODI at 24-month follow-up (n=42,13.8±14.2,27.9±19.4,p<0.05) compared to static implants. Intervertebral disc height increased significantly (p<0.05) from baseline for expandable and static groups at each follow-up through 24 months. At 12-month follow-up the static group had significantly higher subsidence rates. No new subsidence cases developed between 12-month and 24-month follow-up. Conclusion: In this cohort, clinical use of expandable interbody spacers resulted in better outcomes through 24-month follow-up compared to static interbody spacers, with expandable group showing significant improvements in pain and disability than the static group at 24 months.