To conduct a comprehensive morphometric analysis of lumbar pedicle dimensions (L1–L5) in a Turkish population using a linear mixed-effects model (LMM) to establish a reliable anatomical baseline and investigate the impact of sexual dimorphism and bilateral asymmetry. This retrospective study analyzed high-resolution computed tomography (CT) scans of 129 healthy adults (70 females, 59 males; mean age 47.38 ± 17.13 years). Pedicle diameter, length, and transverse angle were measured from L1 to L5. An LMM was employed to account for within-subject dependencies, treating sex and side as fixed effects and subject ID as a random effect. Significant sexual dimorphism was observed, with males generally exhibiting larger pedicle calibers. For L1 diameter, significant main effects were found for sex (p = 0.028) and side (p = 0.001), with left-side measurements being significantly higher in both sexes. Pedicle length demonstrated a consistent left-side dominance across most levels (L1–L5, p < 0.05). A significant sex × side interaction was observed in pedicle transverse angles, particularly at L4 (p = 0.007). In females, the left L4 pedicle angle tended to be greater than the right (p = 0.070), whereas in males, the right-side angle was significantly greater than the left (p = 0.041). Lumbar pedicle morphology in the Turkish population is governed by complex interactions between genetic sex and directional asymmetry. The distinct left-side dominance in length and the unique angular shifts at L4 diverge from findings in other ethnic cohorts. These population-specific nuances are critical for preoperative planning and the selection of optimal screw dimensions. Integrating these variations into surgical practice is essential to enhance the precision of transpedicular instrumentation and minimize neurovascular risks.

KEY WORDS: Bilateral asymmetry; Lumbar vertebrae; Pedicle morphometry; Sexual dimorphism.