Sagittal Lumbar Alignment Following Axial Lumbar Interbody Fusion with TranS1

Design: Retrospective study. Objective: To examine and compare pre/postoperative sagittal alignment of the lumbar spine following AxiaLIF® and to identify patient category with respect to preservation/restoration of lumbar lordosis. Background: Interbody arthrodesisis an effective treatment for lower back pain and provides immediate structural support with high fusion rates. AxiaLIF® is an interbody device to be implanted through a paracoccygeal approach. Sagittal alignment change after AxiaLIF® has not been studied in past literature. Methods: Retrospective study of all patients who underwent a 360° lumbar interbody fusion at L5-S1 and L4-S1 with AxiaLIF® between Nov. 2008 and Sept. 2009. Surgeries were performed with patients prone on a Jackson table. Lumbar Cobb angles were measured at L1-S1, L4-S1 and individual lumbar levels. The sacral slope and percentage of total lordosis coming from the L4-S1 levels were also recorded. Results: 60 patients identified for inclusion (mean age: 44 years). No difference in total average lordosis was observed preoperatively (47.9o) versus postoperatively (47.7o). The difference between pre and postoperative Cobb angles at the L4-S1 and L4-L5 levels was statistically significant (p=0.022 and 0.029, respectively). The change in percentage of total lordosis coming from L4-S1 segments (68.9% preoperatively vs. 56.5% postoperatively) was also significantly different (p=0.0004). A >10o postoperative change in total lordosis, L4-S1, and SS occurred in 18%, 20%, and 11% respectively. 50% and 43% of patients had a >5o change at the individual segments of L4-L5 and L5-S1. Conclusions: A significant portion single and multilevel fusions with AxiaLIF® had a statistically significant change at the L4-5 and L4-S1 levels. The percentage of total lordosis from the L4-S1 level decreased significantly in the multilevel group. Further observation will determine if change in alignment will impact outcomes or accelerate adjacent level disease.