Reproducibility and Accuracy of Pelvic Tilt in Predicting the Difference Between Pelvic Incidence and Lumbar Lordosis Value.

Objective We investigated the pelvic morphologic factors that determine the degree of pelvic incidence (PI)-lumbar lordosis (LL) mismatch. Methods Overall, 306 patients were included. The regional and global sagittal parameters were measured. Linear regression analyses were performed for 4 pelvic parameters and PI-LL mismatch. E1 and E2 were defined as linear regression equations between pelvic tilt (PT) and PI-LL mismatch and PI and PI-LL mismatch, respectively. The patients were categorized by cluster analysis using the hierarchal method for the 4 pelvic parameters. Results E1 and E2 showed statistical significance; however, the coefficient of determination of E1 was higher than that of E2 (R2 = 0.675 vs. 0.238; P Conclusions The individual differences between the PI and LL values can be more accurately determined using the individual PT, and the optimal PT amount will differ depending on the pelvis shape. The increase in the TPA and IAIPs corresponded to the PT, and the SSA increased in accordance with the pelvic size.