The effect of design characteristics on the mechanical stiffness of children's off-the-shelf stability therapeutic footwear

Therapeutic footwear is a frequently used assistive product for children with mobility impairments (Hill et al., 2019). There are several types of therapeutic footwear, with stability therapeutic footwear designed to limit extreme movements of the lower limb to maintain a controlled displacement of the centre of force during gait. A recent study established expert consensus, gained through a standardised Delphi process, on the ideal design characteristics of children’s off-the-shelf stability therapeutic footwear (OSSTF) (Hill et al. 2021). The characteristics were classified into two groups, stability and ergonomics. Some design characteristics were suggested to relate to the stiffness of the components of OSSTF in specific regions of the footwear. With stability thought to be enhanced with increased resistance to movement (stiffness) in a mediolateral direction (e.g., through increased height and length of the heel counter), and ergonomics thought to be enhanced by a lowered resistance to movement (lower stiffness) in an anterior-posterior direction (e.g., through the flexibility of the outsole at the forefoot).