Understanding the effects of quantitatively prescribing passive-dynamic ankle-foot orthosis bending stiffness for individuals after stroke

BACKGROUND Passive-dynamic ankle-foot orthosis (PD-AFO) bending stiffness, which assists plantar flexor function, can be prescribed to improve poststroke gait. However, outcomes with PD-AFOs are variable likely because of improper personalization. We implemented a prescription model that objectively personalizes PD-AFO bending stiffness based on each individual's level of plantar flexor weakness (quantitatively prescribed PD-AFO). OBJECTIVES To evaluate whether a quantitatively prescribed PD-AFO improves peak paretic plantar flexion moment compared with the original AFO for individuals after stroke and to examine the immediate effects of wearing a quantitatively prescribed PD-AFO. STUDY DESIGN This is a repeated-measures study. METHODS PD-AFO bending stiffness was personalized for 10 individuals after stroke through the previously developed prescription model. Participants underwent an instrumented gait analysis while wearing their original AFO and the quantitatively prescribed PD-AFO. RESULTS Participants' peak paretic plantar flexion moment significantly increased while wearing the quantitatively prescribed PD-AFO compared with the original AFO. In addition, participants showed different levels of improvements in a series of other key biomechanical and walking performance parameters with PD-AFO use. Some participants showed improvements in all parameters, whereas others showed moderate to no improvements. CONCLUSIONS Quantitatively prescribed PD-AFO bending stiffness resulted in inconsistent improvements in biomechanical and walking performance parameters, which warrants further investigation. Future work should investigate whether more consistent benefits are seen with faster walking speeds and longer-term PD-AFO use. In addition, future work should conduct larger-scale studies that aim to understand and optimize orthosis-patient matching for all AFO designs/characteristics.