The distribution of screw stress of the different fixators along the bone-screw interfaces (Line AB). The terms “Head”, “Entry”, “Junction”, and “Tip” denote screw head (i.e. screw hub), entry site of pedicle screw into posterior element, interface between posterior element and cortical bone, and screw tip. Flexion(a). Extension(b). Bending(c). Rotation(d).