A Clinical Study to Evaluate Static vs. Expandable Lateral Lumbar Interbody Fusion Devices: With One-Year Follow-up

Presented at SMISS Annual Forum 2018
By Richard Frisch MD
With Ingrid Luna , Daina Brooks BS, Gita Joshua MA, Charles Ledonio MD, CCRP,

Disclosures: Richard Frisch MD B; Globus Medical. F; Globus Medical Ingrid Luna E; Globus Medical, Inc., Daina Brooks BS E; Globus Medical, Inc., Gita Joshua MA E; Globus Medical, Inc., Charles Ledonio MD, CCRP E; Globus Medical,


Static interbody spacers have long been considered the gold standard for treating patients with degenerative disorders of the spine. However, minimally invasive (MIS) lateral lumbar interbody fusion (LLIF) procedures utilizing static spacers may require excessive trailing and forceful impaction, which may lead to iatrogentic endplate disruption, excessive neural retraction, and implant subsidence. The in situ expansion capability offered by expandable interbody spacers facilitates insertion to reduce endplate damage and optimize endplate contact.


This clinical study sought to compare radiologic and clinical outcomes of static and expandable interbody spacers following MIS LLIF and to report device-related complications including implant subsidence.


This study included 64 patients with degenerative disc disease who underwent MIS LLIF at 1-2 contiguous level/s using a polyether-ether-ketone static or a titanium expandable intervertebral spacer. 32 (41 levels) were treated with a static spacer and 32 (42 levels) patients with an expandable spacer. All procedures were combined with supplemental transpedicular posterior stabilization. Analyses were based on the comparison of perioperative outcomes to radiological and clinical metrics.


Mean patient age was 65.8±9.7years (63% female). No significant differences were observed between static and expandable groups in operative time (70±38.1min, 78±48min), estimated blood loss (52±86.2cc, 46±543cc), or length of hospital stay (2.2±1.4days, 2.3±1.2days) (P>0.05). Mean visual analog scale pain, Oswestry Disability Index, and RAND 36-item Health Survey scores improved significantly from preoperative to 12-month follow-up in both groups (P<0.05). Intervertebral disc and neuroforaminal heights increased significantly within each group from preoperative to 12-month follow-up (p<0.01) but were not different between groups (p>0.05). Segmental lordosis increased significantly in the expandable group (14.0° ± 7.9° preoperatively to 16.4° ± 8.8° at 12 months) (p=0.01) but did not increase significantly in the static group (p=0.40). Spacer subsidence was reported in 32.4% of static and 9.8% of expandable interbody spacer levels (p<0.01).


LLIF using expandable interbody spacers resulted in clinical outcomes similar to those of static spacers; however, the expandable group experienced a significantly greater increase in segmental lordosis and a significantly lower subsidence rate than the static group.