Impact of sole designs of offloading AFO on gait dynamics: a predictive neuromechanical simulation study

Individuals suffering from foot and ankle conditions like foot ulcers, fractures, sprains, tendon ruptures, or post-surgical recovery are often advised to minimize loading weight on the affected area. Traditional rehabilitation aids, such as crutches and wheelchairs, significantly limit mobility. Offloading ankle-foot orthoses (AFOs) are designed to redirect ground reaction forces to the shank, thereby bypassing the foot and ankle. This presents a more promising approach to enhance mobility, prevent leg muscle atrophy, reduce bone porosity, and foster a more natural and symmetric gait compared to conventional devices. Here, we employed predictive neuromechanical simulations to investigate the impact of various sole shapes on unilateral offloading AFOs during gait. We simulated scenarios with no AFO, with a flat sole-shaped AFO, and with a circular sole-shaped AFO across various speeds. Our preliminary findings suggest that walking at fast speeds with an AFO requires more effort compared to walking without an AFO. Between the two sole shapes, the circular-AFO could be more effective in terms of muscle effort compared to the flat- AFO across most walking speeds, but other gait features do not show clear advantages. This study lays the groundwork for future research utilizing our neuromechanical simulation platform to optimize AFO designs and rehabilitative use.