Fig. 1.

A, Illustration of a thoracic vertebra, showing the pedicle length (AB), the chord length (AC), the transverse pedicle width (DE) and the transverse pedicle angle (F).^{18, 24, 29, 30} B, Illustration of a lumbar vertebra, showing the pedicle length (AB), the chord length (AC), the transverse pedicle width (DE) and the transverse pedicle angle (F).^{18, 24, 29, 30} C, Illustration of the angle of vertebral rotation (RA_sag). RA_sag is defined as the angle between the bisector of the bilateral longitudinal spinous-foraminal line and vertical axis.^31–35