De-stabilizing and training effects of foot orthoses in multiple sclerosis

This study evaluates the effects of dynamic foot orthoses (DFO) on walking and balance performance in people with multiple sclerosis (MS). Sixteen ambulant subjects with MS and ten age-matched healthy control subjects were studied on initial receipt of foot orthoses and after four weeks of daily wear. Walking speed, MS Walking Scale-12 (MSWS-12) and standing balance were assessed with and without orthoses at both these times. During standing, stance width and vision were varied, and performance was quantified using the velocity of the centre of pressure (COP), body sway velocity and the mean COP position relative to the shoe. People with MS walked slower (P <0.001) and showed increased sway when standing (P <0.001). At the first assessment, the foot orthoses caused an increase in sway and a medial and posterior shift of the COP position. At repeat measurement, the DFOs continued to increase sway compared to a shoe only condition. However, MS subjects reported an improvement in the MSWS-12 (P <0.05) and, compared to the initial session, showed decreased sway when eyes were closed both with and without DFOs. Dynamic foot orthoses may increase sway and change COP position by altering foot alignment and/or plantar afferent stimulation. Improvement in body sway over time may be an overall training effect of the DFOs, as MS subjects adapt to the initial de-stabilization.