Effectiveness Of A Customizable Off-the-shelf Inshoe Orthotic In Controlling Foot Motion During Running.

Abstract

Runners experience high rates of lower extremity injuries. Excessive foot motion is believed to be a factor in these injuries. Inshoe orthotics are a common modality used in the treatment of these injuries. The effectiveness of off the shelf orthotics in controlling foot motion has not been well researched. PURPOSE: This study’s purpose was to assess the effectiveness of a customizable off-the-shelf inshoe orthotic in controlling intersegmental foot motion during treadmill running. METHODS: For this study, 18 recreational runners (4 males, 14 females, mean age 23.8 ± 3.8 and 22.3 ± 1.2 years, respectively) were recruited. Intersegmental foot kinematics were recorded at 240 Hz using a 20-camera motion analysis system while the subjects ran on a treadmill at their self-selected running speed in 3 randomly determined footwear-orthotic stiffness combinations. The rearfoot (RFA) and midfoot (MFS) angles and arch height index (AHI) at initial contact (IC) and midstance (MS) were obtained. The mean change in RFA, MFA, and AHI from IC to MS was then determined for each footwear orthotic combination. A linear mixed model was used to assess the effect of orthotic-footwear condition on the change in AHI, RFA, MFA from IC to MS. RESULTS: The mean change in the frontal plane RFA for the no orthotic, shoe with orthotic at setting 1 (least stiff), and shoe with orthotic at setting 3 (most stiff) was -5.0 ± 0.8, -5.0. ± 0.8, -5.0 ± 0.8 degrees, respectively. The mean change in the frontal plane MFA for the no insole, shoe with orthotic at setting 1, and shoe with orthotic at setting 3 was 0.0 ± 0.3, -1.0 ± 0.3, -1.0 ± 0.3, respectively. The mean change in AHI for the no insole, shoe with orthotic at setting 1, and shoe with orthotic at setting 3 was 0.6 ± 0.01, 0.7 ± 0.01, 0.7 ± 0.01, respectively. A significant effect (p > 0.05) of orthotic condition was not present for any of the variables of interest in this study. CONCLUSIONS: Off-the-shelf customizable orthotics do not appear to affect intersegmental foot kinematics during treadmill running.