Investigation of how different halos influence pin forces.

STUDY

DESIGN

This study investigated the effect of the size and material 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 spine fractures.

METHODS

One standard halo pin and seven different halo rings were used to test the anterior pin hole of each ring at a constant torque of 8 inch-pounds (0.9 Nm).

RESULTS

Pin force fluctuated from halo to halo, and decreased as the nut was tightened.

CONCLUSIONS

Identical torques applied to different halos will not guarantee the same magnitude of pin force for halo fixation.