Halovest dynamic loads: full crossover comparison of three vest types.

STUDY DESIGN: Ten cervical spine trauma subjects were studied during halovest treatment. Each subject wore each of three different vests. OBJECTIVES: To compare the effect of vest design on loads between halo and vest during various activities. SUMMARY OF BACKGROUND DATA: Complications during halovest use may be related to vest design, a variety of which are available. Loads between halo and vest have been shown to vary with activity type, but no comparison between vest types has been reported previously. METHODS: Loads between the halo and the vest were measured during performance of activities of daily living and during load application to the halo, using custom-built four-channel transducers and a PC-based data acquisition system. RESULTS: Substantial variations between subjects exist in loads between the halo and the vest. At rest, neck distraction loads were significantly greater for the supine posture than for either the sitting or standing postures. Loads applied to the halo by the investigators are carried by the neck and not by the structure connecting the halo to the vest. During activities of daily living all four measured load components are generally nonzero. During activities of daily living substantial differences in loads occurred between vest types. For all activities of daily living combined, the relative neck distraction load values were as follows: 4PAD 100%, Bremer 159%, and PMT 180%. CONCLUSIONS: Previous evidence supports a connection between certain complications of halovest wear (such as pin loosening) and loads on the pins. This study shows that different halovests are associated with quite different loads between the vest and the halo (and thus loads on the pins and the neck). This is encouraging for prospective, clinical comparison of different halovests and for improvements in clinical performance through halovest design improvements.