Changes in Segmental and Lumbar Lordosis After Lateral Lumbar Interbody Fusion With Different Lordotic Cage Angulations

Background: Lateral lumbar interbody fusion (LLIF) affords a wide operative corridor to allow for a large interbody cage implantation for segmental reconstruction. There is a paucity of data describing segmental lordosis (SL) achieved with lordotic implants of varying angles. Here we compare changes in SL and lumbar lordosis (LL) after implantation of 6 degrees, 10 degrees, and 12 degrees cages. Methods: We retrospectively reviewed LLIF cases over a 5.5-year period. We derived SL and LL using the standard cobb angle measurement from a standing lateral radiograph. We analyzed mean changes in SL and LL over time using the linear mixed effect model to estimate these longitudinal changes. Results: The most frequently treated level was L3-4, followed by L4-5. Significant increases in mean SL were found at each follow-up time point for all the cohorts. In an intercohort comparison, the mean changes in SL at immediate postoperative and last follow-up were significantly greater in the 10 degrees cohort than 6 degrees ([7.4 degrees versus 3.1 degrees, P =.004], [6.1 degrees versus 2.3 degrees, P =.025] respectively). The 12 degrees cohort had higher mean change in SL at last follow-up than the 6 degrees cohort (5.9 degrees versus 2.3 degrees, P =.022). There was no difference in mean change in SL between the 10 degrees and 12 degrees cohorts. No difference in overall mean LL over time was found. In terms of mean change in LL, no difference was observed except at immediate and 6-month postoperative in the 10 degrees cohort ([9.6 degrees, P =.001], [8.5, P =.003] respectively). By comparing mean change in LL, no difference existed except between the 108 and 68 immediately after surgery (9.6 degrees versus 0.2 degrees, P =.006). Conclusions: LLIF cages significantly improve SL at the index level. However, this increase in SL is greater for 10 degrees and 12 degrees cages than the standard 6 degrees cage. Use of 10 degrees cages also resulted in overall improved LL than 6 degrees cages.