Ankle-foot orthoses in stroke: effects on functional balance, weight-bearing asymmetry and the contribution of each lower limb to balance control.

BACKGROUND Ankle-foot orthoses are often provided to improve walking in stroke patients, although the evidence of effects on walking and balance control is still inconsistent. This could be caused by a lack of insight into the influence of orthoses on the underlying impairments. These impairments can be assessed with dual plate posturography to determine the relative contribution of each lower limb to balance control and weight-bearing. This study examined the effects of ankle-foot orthoses on functional balance, static and dynamic weight-bearing asymmetry and dynamic balance control of the paretic and non-paretic lower limbs. METHODS Twenty stroke subjects (time since stroke 5-127 months) completed the study. Subjects were assessed with and without ankle-foot orthosis. Functional balance was assessed using the Berg Balance Scale, Timed Up & Go test, Timed Balance Test, 10-m walking test and Functional Ambulation Categories. Weight-bearing asymmetry and dynamic balance control were assessed with force plates on a movable platform. FINDINGS No significant effects of ankle-foot orthoses were found for weight-bearing asymmetry and dynamic balance control, but significant differences in favour of ankle-foot orthosis use were found for most functional tests. INTERPRETATION Although ankle-foot orthoses had no effect on weight-bearing asymmetry or dynamic balance contribution of the paretic lower limb, functional tests were performed significantly better with orthoses. Apparently, improvements at functional level cannot be readily attributed to a greater contribution of the paretic lower limb to weight-bearing or balance control. This finding suggests that ankle-foot orthoses influence compensatory mechanisms.