Comparison of in vivo segmental foot motion during walking and step descent in patients with midfoot arthritis and matched asymptomatic control subjects.

The purpose of this study was to compare in vivo segmental foot motion during walking and step descent in patients with midfoot arthritis and asymptomatic control subjects. Segmental foot motion during walking and step descent was assessed using a multi-segment foot model in 30 patients with midfoot arthritis and 20 age, gender and BMI matched controls. Peak and total range of motion (ROM), referenced to subtalar neutral, were examined for each of the following dependent variables: 1st metatarso-phalangeal (MTP1) dorsiflexion, 1st metatarsal (MT1) plantarflexion, ankle dorsiflexion, calcaneal eversion and forefoot abduction. The results showed that, compared to level walking, step descent required greater MTP1 dorsiflexion (p<0.01), MPT1 plantarflexion (p<0.01), ankle dorsiflexion (p<0.01), calcaneus eversion (p=0.03) and forefoot abduction (p=0.01), in all subjects. In addition, step descent also necessitated greater MTP1 dorsiflexion (p<0.01), ankle dorsiflexion (p<0.01) and forefoot abduction (p=0.02) excursion compared to walking. Patients with midfoot arthritis responded differently to the step task compared to control subjects in terms of MT1 and calcaneus eversion excursion. During walking, patients with midfoot arthritis showed significantly less MT1 plantarflexion excursion compared to control subjects (p=0.03). However, during step descent, both groups showed similar MT1 plantarflexion excursion. During walking, patients with midfoot arthritis showed similar calcaneus eversion excursion compared to control subjects. However, during step descent, patients with midfoot arthritis showed significantly greater calcaneus eversion excursion compared to control subjects (p=0.03). Independently or in combination, these motions may contribute to articular stress and consequently to symptoms in patients with midfoot arthritis.