Maximum hyoid displacement in normal swallowing.

Vertical and anterior displacement of the hyoid bone is a critical biomechanical component of normal swallowing function. The purpose of this study was to evaluate the maximal vertical and anterior displacement of the hyoid bone during oropharyngeal swallowing. A retrospective review of video-fluoroscopic swallowing exams in 40 normal subjects varying by age and gender was performed. Means and standard deviations for both vertical and anterior displacement were analyzed on both 5-ml and 10-ml thin liquids using an ImageJ program. Age and gender differences were submitted to a repeated-measures one-way analysis of variance. There was a significant difference between younger and older subjects for anterior displacement of the hyoid bone during the swallow but not for vertical displacement. No significant differences between male and female subjects were observed. Anterior displacement of the hyoid bone decreased with increasing age. This reduction may be related to muscle weakness. However, older people may adapt to preserve airway protection.