INVESTIGATION OF HOW DIFFERENT HALOS INFLUENCE PIN FORCES

Study Design. This study investigated the effect of the size and mater ial of halo rings on the pin force produced at the halo pin-calvarium complex. Summary of Background Data: Loosening of halo pins has been a problem with using the halo-vest apparatus to stabilize cervical spin e fractures. Methods. One standard halo pin and seven different halo r ings were used to test the anterior pin hole of each ring at a constan t torque of 8 inch-pounds (0.9 Nm). Results. Pin force fluctuated from halo to halo, and decreased as the nut was tightened. Conclusions. Id entical torques applied to different halos will not guarantee the same magnitude of pin force for halo fixation.