Page 22 - Maximizing the efficacy of ankle foot orthoses in children with cerebral palsy

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Chapter I
Acclimatizing to a new AFO
Thirdly, AFO efficacy is often assessed by its effect on gait biomechanics, as the mechanical constraint of the AFO is primary expected to alter the gait pattern in terms of joint kinematics and kinetics, and eventually the overall gait performance. When applying an AFO, it could be expected that children with CP may need time to improve their gait pattern to the AFO by adjusting their muscle activation pattern (i.e. motor learning) to the new ankle mechanics[68]. When evaluating effects of an AFO on gait, acclimatization time for the gait pattern to adapt to the mechanical constraints as induced by a new AFO is therefore generally recommended to comply with the learning effect[50]. Accordingly, most testing protocols in research studies allow for acclimatization, although the permitted time varies between six weeks and less than one day[50]. While inadequate acclimatization time has been reported as a potential confounding factor for the efficacy of AFOs in some studies[39,69], it is unknown whether such an acclimatization period is actually required to reliably assess gait biomechanics of a newly prescribed AFO.
In summary, AFOs are widely used to improve gait in children with CP. Scientific evidence for the effectiveness of AFOs is however scarce and inconclusive. Insight in underlying working mechanisms of AFOs is also lacking. Considering the variation in reported effects of AFOs on gait in CP, an individual approach to optimize AFO prescription seems essential to maximize treatment efficacy.
aIM
This thesis aims to evaluate factors that can guide an individual optimization of AFO prescription in order to maximize AFO efficacy in children with CP who walk with excessive knee flexion in stance.
oUtLIne
The chapters of this thesis are primarily based on results of the AFO-CP trial, which was initiated to get insight in underlying working mechanisms of AFOs and to provide evidence for AFO effectiveness in children with CP walking with excessive knee flexion in stance. The study specifically aimed to individually optimize AFO stiffness to maximize the gait efficiency in these children. The protocol of the AFO-CP study is described in Chapter II.