An individual approach for optimizing ankle-foot orthoses to improve mobility in children with spastic cerebral palsy walking with excessive knee flexion

- Optimizing Ankle-Foot Orthosis stiffness results in clinically relevant gait changes.
- A stiffness-optimized ventral shell Ankle-Foot Orthosis improves knee flexion in stance.
- A stiffness-optimized ventral shell Ankle-Foot Orthosis may improve gait efficiency.
- Gait responses varied following Ankle-foot Orthosis stiffness optimization.
- An individual approach to Ankle-Foot Orthosis prescription is emphasized.

Ankle-Foot Orthoses (AFOs) are commonly prescribed to promote gait in children with cerebral palsy (CP). The AFO prescription process is however largely dependent on clinical experience, resulting in confusing results regarding treatment efficacy. To maximize efficacy, the AFO's mechanical properties should be tuned to the patient's underlying impairments. This study aimed to investigate whether the efficacy of a ventral shell AFO (vAFO) to reduce knee flexion and walking energy cost could be improved by individually optimizing AFO stiffness in children with CP walking with excessive knee flexion. Secondarily, the effect of the optimized vAFO on daily walking activity was investigated. Fifteen children with spastic CP were prescribed with a hinged vAFO with adjustable stiffness. Effects of a rigid, stiff, and flexible setting on knee angle and the net energy cost (EC) [J kg−1 m−1] were assessed to individually select the optimal stiffness. After three months, net EC, daily walking activity [strides min−1] and knee angle [deg] while walking with the optimized vAFO were compared to walking with shoes-only. A near significant 9% (p = 0.077) decrease in net EC (−0.5 J kg−1 m−1) was found for walking with the optimized vAFO compared to shoes-only. Daily activity remained unchanged. Knee flexion in stance was reduced by 2.4° (p = 0.006). These results show that children with CP who walk with excessive knee flexion show a small, but significant reduction of knee flexion in stance as a result of wearing individually optimized vAFOs. Data suggest that this also improves gait efficiency for which an individual approach to AFO prescription is emphasized.