Morphometric Study of the Pedicles of Lumbar Vertebrae in Koreans

ABSTRACT

OBJECTIVE: This study was undertaken to study pedicle morphology in Koreans to provide a reference guide in transpedicular screw fixation. METHODS: Pedicle measurements were obtained from 35 dried human lumbar columns(175 lumbar vertebrae). Anatomic evaluation was focused on pedicle transverse diameter, pedicle axis length and the distance from the pedicle axis point to the midline of the transverse process. Pedicle angle and vertebral body length also were measured. RESULT: In the transverse plan, pedicle diameter increased from L1(7.8mm) to L5(15.5mm). But in 20.0% of L1 and L2, its diameters was under 6.0mm. In the sagittal plan, it was not as constant and had similar diameter from L1 to L5. In the transverse plan, the pedicle angle increased from L1 to L5. But in the sagittal plan it decreased from L1 to L5. Also, the pedicle axis length did not show concordant change, but rather had similar length in lumbar vertebrae. In 15%, its length was under 45mm. CONCLUSION: These results suggest that using above 6mm diameter and 45mm length of screw for L1 and L2 can violate the pedicle and vertebrae. Above L4, the pedicle axis point was superior to the midline of the transverse process, below L4, it was inferior to the midline of the transverse process. This information may prove to be helpful when contemplating the placement of screws to the lumbar pedicles.