The foot is the base of the musculoskeletal system and much attention has been given to its role in lower extremity injuries. Unfortunately, there is great disparity in existing literature. Arch height of the foot, is reported to effect injury risk and it is suggested that if an individual has a high, low or either extreme of arch height individuals are at an increased risk of injury. Conversely, there are numerous reports that refute any such association, Reports on arch mobility are scarce and provide little help in clarfiying the role of toot morphology as an injury risk factor. Although there is great debate regarding the role of the foot and incidence of injury, looking at both arch height and mobility may provide a better understanding of the role of the arch of the foot has with injury. Therefore, the purpose of this doctoral dissertation is three-fold: 1, to develop a functional arch score representing arch height and mobility; 2. to determine the predictive value of this functional arch score; and 3. to determine if foot morphology influences function. 1143 active duty US Army Soldiers were enrolled in this investigation. Two arch height and nine arch mobility measures were assessed; sitting arch height index and relative arch mobility were selected to calculate a functional arch score on categorical and continuous scales. The catagorical scale was deemed most appropriate and defined by nine arch types: 1. Low-Hypo, 2. Normal-Hypo, 3. High-Hypo, 4. Low-Normal. 5. Normal-Normal, 6. High-Normal, 7. Low-Hyper, 8.Normal-Hyper, 9. High-Hyper. Using this categorical version of the functional arch score, if injured, a subject’s odd of a lower extremity injury were greatest for High-Hypo or a Low-Hyper foot. Lastly, specific foot types influenced function as measured by ankle mobility and dynamic balance on the Y balance test. Subjects with Normal-Hypo had statistically less maximum closed chain dorsilfexion than Normal-Hyper and High-Hypo. Normalized to leg length, anterior reach distances were the shortest among Normal-Hypo arches than both Low-Normal and Normal-Hyper arches. Maximum composite scores are greater among subjects with Low-Normal than Normal-Hypo and High-Normal arches. The outcome of this research demonstrate the value of a comprehensive objecitve measure of foot morphology. These findings demonstrate the combination of extreme arch height and mobility are most highly associated with lower extermity injury. Lastly, differences in functional measures, ankle mobility and postural control, demonstrate the appropriateness in applying principles of regional interdependence to investigate foot morphology. This research brings a new perspective to the discussion table regarding the interaction of arch height and mobility on injury and function and will serve as a platform for future research.
