A novel method to evaluate the transverse pedicle angles of the lower lumbar vertebrae using digital radiography.

To investigate a novel approach for establishing the transverse pedicle angle (TPA) of the lower lumbar spine using preoperative digital radiography (DR). Computed Tomography (CT) datasets of the lower lumbar were reconstructed using MIMICS 17.0 software and then imported into 3-matic software for surgical simulation and anatomical parameter measurement. A mathematical algorithm of TPA based on the Pythagorean theorem was established, and all obtained data were analyzed by SPSS software. The CT dataset from 66 samples was reconstructed as a digital model of the lower lumbar vertebrae (L3-L5), and the AP length/estimated lateral length for L3 between the right and left sides was statistically significant (P = 0.015, P = 0.005). The AP length of the right for L4 was smaller than that of the left after a paired t test was executed (P = 0.006). Both the width of the pedicle and the length of the pedicle (P2C1) were consistent with TPA (L3<L4<L5). There were no significant differences in TAN-TPA and DR-TPA compared with real TPA. The ICCs for the real TPA and DR-TPA within L3 showed good reliability, and the ICCs for the real TPA and DR-TPA within both L4 and L5 showed moderate reliability. Our novel approach can be considered a reliable way to determine the transverse pedicle angle from routine DR, and the width and length of the pedicle within lumbar DR should be considered to determine the length and trajectory of the screw during preoperative planning.