Friday, 29 August 2014

Ankle-foot orthoses that restrict dorsiflexion improve walking in polio survivors with calf muscle weakness

H.E. Ploeger, S.A. Bus, M.A. Brehm, F. Nollet

Abstract
In polio survivors with calf muscle weakness, dorsiflexion-restricting ankle-foot orthoses (DR-AFOs) aim to improve gait in order to reduce walking-related problems such as instability or increased energy cost. However, evidence on the efficacy of DR-AFOs in polio survivors is lacking. We investigated the effect of DR-AFOs on gait biomechanics, walking energy cost, speed, and perceived waking ability in this patient group.

Sixteen polio survivors with calf muscle weakness underwent 3D-gait analyses to assess gait biomechanics when walking with DR-AFOs and with shoes only. Ambulant registration of gas-exchange during a 6-minute walk test determined walking energy cost, and comfortable gait speed was calculated from the walked distance during this test. Perceived walking ability was assessed using purposely-designed questionnaires.

Compared with shoes-only, walking with DR-AFOs significantly increased forward progression of the center of pressure (CoP) in mid-stance and it reduced ankle dorsiflexion and knee flexion in mid- and terminal stance (p  < 0.05). Furthermore, walking energy cost was lower (-7%, p = 0.052) and gait speed was higher (p = 0.005). Patients were significantly more satisfied, felt safer and less exhausted with the DR-AFO, compared to shoes-only (p  < 0.05). DR-AFO effects varied largely across patients. Patients who walked with limited forward CoP progression and persisting knee extension during the shoes-only condition seemed to have benefitted least from the DR-AFO.

In polio survivors with calf muscle weakness, DR-AFOs improved gait biomechanics, speed and perceived walking ability, compared to shoes-only. Effects may depend on the shoes-only gait pattern, therefore further study is needed to determine which patients benefit most from the DR-AFO.

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