The Effect of Special Shoe Designed For Off Loading on Plantar Foot Pressure Distribution

Introduction: After forefoot surgery or in order to reduce pressure in foot ulcer, unload shoe is indicated. This lead to leg length discrepancy in the contralateral foot and abnormal gait. In order to correct this leg length discrepancy a Twin Shoe in the normal foot was developed. The objective of this study is to evaluate the off-loading in the surgical foot wearing Ortho Wedge Darco® and comparing the results wearing a contralateral normal shoe with and without elevation.

Methods: 20 healthy subjects (age range 20-45 years) with no abnormal gait pattern. Plantar pressures were measured and 3 types of shoes were used in this experiment. Ortho Wedge Darco® shoe was worn on the right foot in two experimental conditions. A personal neutral running shoes was worn on the contralateral foot in one experimental condition. The same shoe with an added elevation (designed to reduce bi-lateral leg discrepancy caused by the DARCO) was worn in the second experimental condition. Pressure time integral (PTI) [KPa*s] and peak plantar pressure (PP) [KPa] were calculated.

Results: An increase in the lateral midfoot PP (+8.7%). An increase in lateral midfoot (+11.3%), lateral metatarsals (10.3%) and lateral toes (33.3%) and a decrease in mid-heel (-7.5%) and lateral heel (-5.0%) were observed in PTI.

The effects of wearing the elevated shoe caused compared to the same foot with a regular shoe an increase in of 20.5% in medial midfoot and a decreases of 23.1% in 2^nd metatarsal and 23.2% in lateral metatarsal in the PP. The effects on PTI were an increase in medial heel (+29.2%), lateral heel (+25.2%) and midfoot (63.2%) with a decrease in the 2^nd metatarsal (-24.5%) and lateral metatarsals (-33.0%).

Conclusion: Elevating the contralateral foot will improve the gait but reducing the unload force in the surgical site. It could be dangerous for a recent ostotomy, wear bilateral shoe in order to correct the gait