A novel method to evaluate transverse pedicle angle of lower lumbar using digital radiography

Abstract

To investigate a novel approach of establishment for transverse pedicle angle (TPA) of lower lumbar spine using preoperative digital radiography(DR). CT dataset of the lower lumbar were reconstructed using MIMICS 17.0 software, then imported into the 3matic software for surgical simulation and anatomical parameters measurement. Mathematical algorithm of TPA based on Pythagorean theorem was established, all obtained data was analysised by SPSS software. CT dataset from 66 samples were reconstructed as digital model of lower lumbar vertebrate(L3-L5), AP length / estimated lateral length for L3 between right and left were significant statistically(P = 0.015, P = 0.005). AP length of right for L4 was smaller than that of left after Paired t-test was executed(P = 0.006). Both width of pedicle and length of pedicle (P2C1) are consistent with TPA(L3 < L4 < L5). No statistical differences in TAN-TPA and DR-TPA compared with real TPA. ICC for real TPA and DR-TPA within L3 is good reliability, ICC for real TPA and DR-TPA within both L4 and L5 are moderate reliability. Our novel approach can be well considered as a reliable way to determine the transverse pedicle angle from routine DR, width and length of pedicle within lumbar DR should be considered to determine the length and trajectory of screw during preoperation planning.