Study Design Retrospective study. Objective To evaluate and compare bone density along the traditional pedicle trajectory(TPT), cortical bone trajectory(CBT), and modified cortical bone trajectory(mCBT) using computed tomography(CT)-derived Hounsfield unit(HU) measurements. Methods CT scans of the lumbar spine (L1–L5) of adult patients undergoing CT for non-spinal indications (predominantly younger adults) were retrospectively analyzed. Three pedicle screw trajectories were virtually simulated: TPT, CBT, and mCBT. For each trajectory, CTHU values were measured in sagittal section at four anatomical points along the screw path: posterior cortex, mid-pedicle, mid-vertebral body, and anterior vertebral body cortex using multiplanar reconstruction. Mean CTHU values, maximum screw lengths were compared across trajectories, and subgroup analyses were performed for age and sex. Results A total of 350 patients (1750 vertebrae) were analyzed. Mean CTHU values differed significantly among trajectories: CBT (538.2 ± 73.1HU) >mCBT (472.6 ± 87.9HU) >TPT (362.8 ± 68.4HU) ( P < .001). At the posterior cortex, density was highest for CBT (1128.9 ± 147.6 HU), followed by mCBT (962.4 ± 192.7 HU) and TPT (582.1 ± 162.3HU). Across mid-pedicle, mid-body, and anterior cortex, CBT and mCBT showed comparable values, both significantly greater than TPT. mCBT showed significantly increased length of screw compared to CBT and TPT( P < .001). Age negatively correlated with CTHU across all trajectories, most pronounced in TPT (r = −0.36,R 2 = 0.13). Gender differences were significant only for TPT ( P < .05). Conclusion In this radiographic anatomical study of predominantly young adults, CBT and mCBT trajectories traversed higher CT-HU than the traditional pedicle path. These observations are hypothesis-generating and require validation in DEXA-verified osteoporotic cohorts and biomechanical and clinical studies before clinical recommendations can be made.
Rajeev et al. (2026) studied this question.