Effect of foot posture and inverted foot orthoses on hallux dorsiflexion

A pronated foot posture is considered to be a factor in limitation of dorsiflexion at the first metatarsophalangeal joint during weightbearing. Customized foot orthoses are widely used to increase dorsiflexion at the first metatarsophalangeal joint in people with pronated feet. However, the effect of foot posture and customized foot orthoses on maximum first metatarsophalangeal joint dorsiflexion has not been widely investigated. This study sought to determine 1) the relationship between foot posture and static maximum first metatarsophalangeal joint dorsiflexion and 2) the effect of customized foot orthoses on static maximum first metatarsophalangeal joint dorsiflexion in people with pronated feet. Foot posture was assessed using the Foot Posture Index. Static maximum first metatarsophalangeal joint dorsiflexion of the right foot was determined using a goniometer while participants stood relaxed with and without Blake-style inverted (30 degrees) foot orthoses positioned under their feet. There was a significant negative correlation between Foot Posture Index and static maximum first metatarsophalangeal joint dorsiflexion (r = -0.587). Inverted (30 degrees) foot orthoses increased the magnitude of static maximum first metatarsophalangeal joint dorsiflexion from 83.4 degrees to 85.3 degrees in participants with an excessively pronated foot posture. However, this difference was not statistically significant. People with pronated feet are more likely to exhibit limitation of dorsiflexion at the first metatarsophalangeal joint during gait, and inverted foot orthoses are unlikely to be effective in increasing dorsiflexion at the first metatarsophalangeal joint in these people.