Modelling based Approach towards Evaluation and Selection of Ankle Foot Orthosis for Crouch Gait

Ankle foot orthosis (AFO) are commonly prescribed for correcting crouch gait in children with cerebral palsy (CP). There are multiple AFO variants and selecting an optimal AFO for CP subject is often challenging. In this work, we have analyzed the effect of two passive AFO, naming Ground reaction AFO (GRAFO) and Leaf spring AFO (LSAFO) on varying severity of crouch gait in a musculoskeletal simulation environment. Impact of GRAFO and LSAFO on muscle loading and recruitment, in terms of muscle 'impulse', 'yank' and 'coactivation' was investigated for children with crouch gait along with normal gait of typically developing children. Simulation results show increased activation of the dorsiflexor muscles, indicating better ankle control and a net reduction in ankle coactivation for both types of AFO. Compared to GRAFO, LSAFO produced lower energetic cost of walking. The simulation pipeline enables to quantify the effect of different AFO configuration on muscle behavior and recruitment, and can be used to design personalized AFO as per subject-specific gait dynamics.