Soft vs. Traditional AFOs: A Comparative Study on Gait Kinematics, Kinetics, and Muscle Activity

Reduced toe clearance during the swing phase of gait, often referred to as foot drop, is a common cause of walking disability in clinical populations like stroke, cerebral palsy, or multiple sclerosis. Individuals with foot drop often wear an ankle-foot orthosis (AFO) to prevent excessive plantarflexion, but many commercially available AFOs overly restrict ankle mobility or make the wearer feel unstable/uncomfortable. Soft AFOs—AFOs with soft attachment points and elastic assistance—are designed to retain ankle mobility and comfort. However, their effect on gait biomechanics, as compared to traditional AFOs, is not well understood. Therefore, the objective of the current study was to perform a comprehensive biomechanical and neurophysiological comparison of soft AFOs with traditional AFOs. Sagittal plane kinematics, ground reaction forces, and lower extremity muscle activation were measured in 23 neurologically intact individuals while walking on a treadmill without assistance from an AFO (No AFO) and then with unilateral assistance from four commercially available AFOs (rigid anterior, flexible posterior leaf spring, and two soft AFOs). We found that soft AFOs allowed for greater ankle dorsiflexion velocity, plantarflexion velocity, and plantarflexion angle while retaining or increasing dorsiflexion during the swing phase. We also found that the traditional AFOs reduced propulsive ground reaction forces compared to the soft AFOs, and the rigid anterior AFO reduced plantarflexor muscle activity compared to the soft AFOs. These results highlight the differences between different commercially available AFOs and present soft AFOs as an exciting alternative to traditional AFOs when ankle mobility is desired.