The effect of end screw orientation on the stability of anterior instrumentation in cyclic lateral bending.

Background Context: Screw pullout at the proximal or distal end of multilevel anterior instrumentation can occur clinically. Previous laboratory studies have shown that angulation of vertebral body screws increases screw pullout strength and stability in toggling.

Purpose: To determine the effect of end screw angulation on instrumentation construct stability after cyclic, lateral bending.