Article Abstract

Clinical and radiographic analysis of expandable versus static lateral lumbar interbody fusion devices with two-year follow-up

Authors: Richard F. Frisch, Ingrid Y. Luna, Daina M. Brooks, Gita Joshua, Joseph R. O’Brien


Background: Utilization of static and expandable interbody spacers for minimally invasive lateral lumbar interbody fusion (LLIF) offers favorable clinical results. However, complications such as implant migration and/or subsidence may occur with a static implant. Expandable devices allow for in situ expansion to optimize fit and mitigate iatrogenic endplate damage during trialing and impaction. This study sought to compare clinical and radiographic outcomes of static and expandable spacers following LLIF and report device-related complications.
Methods: This study included 29 patients who underwent LLIF with a static spacer and 27 with an expandable spacer; all procedures were combined with supplemental transpedicular posterior fixation. Patient self-assessment forms and radiographic records were used to assess clinical and radiologic outcomes.
Results: Mean patient age was 62.3±10.3 years (64% female). One-level surgery was performed in 87.5% of patients, and 12.5% underwent two-level surgery. Results showed no significant differences in blood loss or length of hospital stay (P>0.05). However, operative times differed statistically between static (63.3±37.8 min) and expandable (120.2±59.6 min) groups (P=0.000). Mean visual analog scale (VAS) and Oswestry Disability Index scores improved significantly from preoperative to 24-month follow-up in both groups (P<0.05). Preoperative intervertebral and neuroforaminal height increased significantly in both groups (P<0.01). Fusion was observed in all operative levels in the static and expandable spacer groups by 24-month follow-up. Implant subsidence was reported in 16.1% of static levels and none of the expandable levels (P<0.01). Postoperative radiographs showed no evidence of implant migration, and no cases required surgical revision at the index or adjacent levels.
Conclusions: LLIF using expandable spacers resulted in similar clinical and radiographic outcomes when compared with using static spacers, and led to a lower subsidence rate.