The Optimal Method to Assess the Vertical Mobility of the Midfoot: Navicular Drop versus Dorsal Arch Height Difference?

Abstract

Background: Clinical measurements that assess the vertical mobility of the midfoot are utilized to assist the clinician in understanding general foot mobility as well as when prescribing foot orthoses and footwear. The primary purpose of this study was to determine the level of intra-rater and inter-rater reliability for navicular drop and dorsal arch height difference using both experienced and inexperienced raters at two geographical locations. In addition, the relationship between navicular drop and the dorsal arch height difference was assessed and normative values for these measurements were provided. Methods:One hundred and ninety-two healthy participants, from two geographical locations, volunteered to participate in the study. Six raters performed the foot measurements required to calculate navicular drop and dorsal arch height difference. These measurements were assessed on 107 female and 85 male participants. Twenty participants from each geographical location were assessed in two sessions, separated by one week, to determine the reliability of the measurements. Results: All foot measurements were shown to have high levels of intra-rater and inter-rater reliability. The strength of the correlation between navicular drop and the dorsal arch height difference was poor indicating that the two measures are not equivalent and cannot be used interchangeably by clinicians when assessing the vertical mobility of the midfoot. Conclusion: While both measures have high levels of reliability, the dorsal arch height difference requires a special non-weight bearing platform as well as patient/client feedback to properly position the platform. As a result, the authors recommend the use of navicular drop as the method of choice for the assessment of the vertical mobility of the midfoot.