The purpose of this research was to examine the relationship between the degree of interbody cage lordosis and cage location and the degree to which sagittal alignment is altered following single-level transforaminal lumbar interbody fusion (TLIF).

Both sagittal and lumbopelvic alignment is important, and studies have found that they predict how well patients will do after surgery. Although TLIF is 1 treatment that has the potential to enhance these parameters, it is not known whether increasing the amount of cage lordosis improves segmental or lumbar lordosis (LL).

All patients with a single-level TLIF with a 5-degree or 12-degree lordotic cage were analyzed retrospectively. Cage position, cage subsidence, LL, segmental lordosis (SL), disk height, and cage position (CP) ratio were measured. The Spearman correlation coefficient was utilized to analyze the relationship between the ratio of the vertebral bodies and the lordotic rotation.

Multiple linear regression was used in a secondary analysis to identify unrelated factors that contributed to the SL change. In the end, 126 people were considered; 51 were sent to the 5-degree cage, and 75 were assigned to the 12-degree cage. A month after surgery, there were no significant changes in postoperative minus preoperative LL (∆LL) (12-degree cage: -1.66 degrees vs. 5-degree cage: -2.88 degrees, P=0.528) or ∆SL (12-degree cage: -0.79 degrees vs. 5-degree cage: -1.68 degrees, P=0.513). Neither LL (12-degree cage: 2.40 degrees vs. 5-degree cage: 1.00 degrees, P=0.497) nor ∆SL (12-degree cage: 1.24 degrees vs. 5-degree cage: 0.35 degrees, P=0.541) differed significantly between the 2 groups after the last follow-up. Demographic variables, cage orientation, and lordosis were not found to be significant predictors of SL change following regression analysis.

Subsidence rates were comparable between the 2 groups (25.5% in the 12-degree cage and 32.5% in the 5-degree cage, P=0.431). Changes in LL, SL, or cage subsidence during surgery for a single-level TLIF were unrelated to lordotic cage angle or location.