Comparison of first ray dorsal mobility among different forefoot alignments

Study Design: Experimental design using 1-way analysis of variance and regression analysis to test the influence of 3 forefoot alignments on the dorsal mobility of the first ray. Objectives: To determine the effect of forefoot alignment on the magnitude of first ray dorsal mobility to an imposed load and to describe any association between forefoot alignment and age on dorsal mobility of the first ray. Background: Instability of the first ray has been implicated as a primary mechanical etiology of many foot problems. It has been proposed that a relationship exists between forefoot alignment and mobility of the first ray, with a varus aligned forefoot contributing to the development of an unstable first ray. Methods and Measures: Sixty female (n = 34) and male (n = 26) subjects aged 18-77 were assigned into valgus, neutral, and varus foot groups (20 per group) based on a clinical measurement of forefoot alignment. A load cell device measured dorsal mobility of the first ray under a standard load of 55 N. Within-day repeat measures were taken from a subsample of subjects. In addition to reliability analysis, analysis of variance and regression analyses tested the relationship between forefoot alignment, age and sex, and mobility of the first ray. Results: The forefoot valgus group demonstrated significantly less dorsal mobility of the first ray than neutral or varus groups. The varus and neutral groups were not significantly different from one another. Forefoot alignment and sex were significant linear predictors (R² = 0.40) of first ray dorsal mobility. Age had no significant association to dorsal mobility of the first ray. Conclusion: Subjects having a valgus aligned forefoot had less dorsal excursion of the first ray than subjects having a neutral aligned forefoot. This investigation provides evidence supporting a relationship between forefoot alignment and mobility of the first ray.