A preliminary study into the immediate effects of ankle foot orthoses of varying design on the walking of people in the early stages of stroke recovery and healthy individuals

Ankle foot orthoses (AFO’s) are prescribed to patients who have ankle impairments causing difficulty walking following stroke. The evidence regarding the benefit of prescribing AFO’s, particularly with regard to type of AFO and timing of intervention, is unclear. There are few studies that investigate the effect of AFO’s in the subacute phase following stroke and few studies that compare different types of AFO. There is little evidence regarding the effect of AFO’s on the gait of normal healthy individuals. This study aimed to compare the effects on walking in different AFO’s, of varying degrees of rigidity, in participants in the early stages of stroke walking recovery and in healthy individuals. Thirteen participants (ten male) in the subacute phase of stroke recovery, aged 23-71 years (M=52.3+13.9), and thirteen age and gender matched healthy participants, aged 26-70 years (M=52.2 +13.1), were recruited to the study. Stroke participants were included if they had a unilateral hemiparesis, were less than 20 weeks post stroke, able to walk with or without supervision and had a motor deficit of the ankle dorsiflexors. Temporal distance gait measures were collected using the GAITRite mat (CIR Systems GRG-24, United States, 80Hz) and knee angles throughout the stance phase, were collected using Silicon Coach Pro software™ (version 7, Silicon Coach Pty Ltd, Dunedin, New Zealand). Stroke participants were tested across three consecutive days, whilst the healthy participants were tested on a single occasion in barefoot, shoes, and three AFO types of varying rigidity: push aequi brace, spring leaf AFO and in a fibreglass cast Each group of participants were familiarised to walking in each AFO. Group differences across the five conditions were assessed using the Friedman’s Test. The ‘smallest real difference’ measure was used to determine the degree of individual improvement with use of the AFOs compared to the shod walking. The results indicated the healthy participants walking performance exceeded that of the stroke participants for velocity, cadence, double limb support, step length, single support phase, single support symmetry, but not swing phase or knee angle at initial contact, midstance or terminal stance for each of conditions tested. Group analysis demonstrated that use of an AFO did not improve walking for the stroke participants: who walked at 46.0 cm/sec (SD: 25.9) in shoes, compared with 46.9 cm/sec (SD: 24.4) in an AFO (p= 0.507). However it caused deterioration in walking in the healthy participants, as demonstrated by a 11.9cm/sec deterioration in a AFO (120.1cm/sec +14.2) in comparison to shoes (132.0cm/sec +16.1) (p=0.002) with similar deteriorations in cadence (shoe: 113.1 steps/minute +7.1; AFO: 102.2 +30.7; p=0.009), step length (shoe: 69.9cm +7.9; AFO: 66.0 +7.2; p=0.002), single stance phase (shoe: 37.1% +1.3; AFO 36.0 +1.3; p=0.009), swing phase (shoe: 37.2% +1.4; AFO: 37.7 +1.1; p=0.039), stance symmetry (shoe: -0.63 +2.9; AFO: -4.9 +3.1; p=0.004) and knee angle at initial contact (shoe: 1.92 degrees +3.9; AFO:3.6 +2.6; p=0.049). The results demonstrating the more rigid the AFO the greater the deterioration for the healthy participants. The smallest real differences of the stroke group indicated that for five participants at least one type of AFO improved their walking. The findings of this study do not support the routine prescription of AFO’s following stroke to patients with ankle impairment. As the walking of the healthy participants deteriorated, there is the suggestion that the application of an AFO may be detrimental. As AFO’s have been demonstrated to improve walking performance by increasing velocity, step length or affected leg stance percentage of the gait cycle for some participants the prescription of an AFO should not be discounted. Prior to prescription of an AFO to a stroke patient careful assessment should occur. Following the prescription of an AFO ongoing assessment is required to examine whether the AFO yields a benefit. Future research should consider the analysis of individual responses in addition to group analysis.