The effect of eliminating leg length difference on plantar foot pressure distribution in patients wearing forefoot offloading shoe

Abstract

Background and purpose: Elevated heel construction offloads the forefoot after surgery. However, side-to-side height difference alters limb kinetics, whereas leg-length equalizing-sole at non-operated side may have beneficial effects on foot loading. The purpose of this study was to characterize leg-length equalizing sole effect on bilateral plantar pressures when using heel-lift forefoot-offloading shoe.

Materials and methods: Twenty men were tested walking. Plantar peak pressures (PP) and pressure-time integrals (PTI) in the forefoot-offloading shoe and in contralateral running shoe were compared between two conditions: one with- and the other without leg-length equalizing sole elevation at the running shoe.

Results: Adding leg-length equalizing sole to the running shoe resulted in the following changes in the forefoot-offloading shoe: increased lateral midfoot PP (8.7%, p=0.03), increased lateral midfoot (11.3%, p=0.05) and lateral metatarsals PTI (10.3%, p=0.04), and decreased medial and lateral heel PTI (>5%, p=0.02). These changes were non-significant when applying a Bonferroni correction. Changes in the running shoe were: increased medial midfoot (20.5%, p=0.03) and decreased 2nd and lateral metatarsals PP (23%, p<0.01). PTI increased in medial and lateral heel (>25%, p<0.01), medial midfoot (63.2%, p<0.01) and lateral midfoot (9.2%, p=0.04) and decreased in 2nd and lateral metatarsals (>24.5%, p<0.01).

Conclusion: Leg-length equalizing sole at contralateral running shoe in subjects wearing forefoot-offloading shoe results in lateral load shift alongside heel pressure attenuation within the forefoot-offloading shoe, which is beneficial during first month after medial forefoot surgery. Reciprocal medial load-shift in the elevated running shoe itself should yet be considered when bilateral medial forefoot pathology is present.

Keywords: Forefoot offloads; Leg length; Plantar foot pressure.