The effect of the kinetic wedge on Hallux dorsiflexion in patients with functional Hallux limitus and severely pronated feet

Abstract

Background: Functional Hallux Limitus is a condition in which there is adequate dorsiflexion of the first metatarsophalangeal joint in nonweightbearing conditions, but with limited dorsiflexion of the first metatarsophalangeal joint during gait. This can be due to the first metatarsal being unable to plantarflex adequately during gait, due to tension in the plantar fascia (caused by excessive pronation) creating a plantarflexion moment on the proximal phalanx of the hallux, or due to the inefficiency of the peroneus longus muscle to stabilize the first ray. The kinetic wedge is an adaptation designed by Dananberg which involved the use of a cut out under the first metatarsal head, this allows the first ray to plantarflex more freely. Dananberg claims that the kinetic wedge increases dorsiflexion at the first metatarsophalangeal joint Aim & Objectives: The aim of the study was to assess whether the kinetic wedge affects first metatarsophalangeal joint dorsiflexion in feet with severe pronation and Functional Hallux Limitus. The objectives included measuring first metatarsophalangeal joint dorsiflexion with the use of three-dimensional motion analysis, and assessing if there was a difference in first metatarsophalangeal dorsiflexion with or without the kinetic wedge. Design & Methods: To evaluate the effect of the kinetic wedge on first metatarsophalangeal joint dorsiflexion a quantitative, quasi-experimental, one-group pretest-postest design study was employed. A group of participants (n=12), of average age 22 (Range 19-28), with a foot posture index score of greater than +10 and a positive Hubscher manoeuvre, but otherwise healthy individuals were chosen. A number of static and dynamic measurements were recorded using a three-dimensional optoelectronic motion analysis system. Measurements were taken in three different settings: barefoot, shoe intervention (which involved the shoe with the Vasyli Howard Dananberg orthoses, without the kinetic wedge) and kinetic intervention (which involved the shoe with the Vasyli Howard Dananberg orthoses with the kinetic wedge). First metatarsophalangeal joint dorsiflexion was calculated by subtracting the static angle from the dynamic angle for each respective setting. Results: No significant difference in first metatarsophalangeal joint dorsiflexion was noticed when comparing the shoe intervention to the kinetic intervention indicating that the kinetic wedge did not significantly affect hallux dorsiflexion (P= 0.075). However, first metatarsophalangeal dorsiflexion was significantly higher in the barefoot setting when compared to the shoe and kinetic interventions (P= 0.000). Conclusion: The kinetic wedge did not have a significant effect on first metatarsophalangeal joint dorsiflexion. Even though the shoe was flexible, there was still a significant decrease in first metatarsophalangeal dorsiflexion in the shoe intervention when compared to the barefoot walking. There is need for further research regarding the effect of orthoses and footwear on first metatarsophalangeal joint dorsiflexion and the incidence of structural hallux limitus in relation to foot posture and Functional Hallux Limitus.