J Clin Neurol Neurosurg Spine 1(1):113, 2017

Static versus Expandable Interbody Spacers: Preliminary 1-Year Clinical and Radiographic Results

Richard F Frisch(1*), Ingrid Y Luna(2) and Gita Joshua(2)

Author information:
(1) Department of Spine, Southeastern Spine Institute, USA
(2) Musculoskeletal Education and Resource Center (MERC), a Division of Globus Medical Inc., USA.


To compare the clinical and radiographic outcomes of static versus expandable interbody spacers following minimally invasive Lateral Lumbar Interbody Fusion (LLIF).


Sixty-four patients were included in this study: 32 who underwent LLIF with a static spacer, and 32 with an expandable spacer. Supplemental transpedicular posterior fixation was used in all cases. These patients were followed for 12 months post-operative. Clinical and radiographic outcomes were assessed using patients’ self-reported forms and radiographs.


Patient age, sex, operative time, blood loss, and length of hospital stay were similar between the static and expandable spacer groups (p>0.05). Mean visual analog scale, 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 12months) (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.