Over-the-Counter Customised Insoles for Offloading Foot Focal Pressure

Purpose: Over-the-counter prefabricated offloading relief insoles with removable modular cells for customisation have not been extensively studied in literature, and no studies have examined designs specifically intended for calluses and corns. This study examined the immediate effects of such insole prototype on the users. Methods: Foot pressure distribution was measured by in-shoe F-Scan system during normal walking cycles under four conditions: walking with normal footwear (C1), with prototype insoles inside the footwear (C2), with a cavity under the second metatarsal-phalangeal joint on the left or right side of the prototype insole (C3), and with cavities on both sides on the prototype insoles (C4). Subjective data were also collected in terms of insole fitting, comfort rating and balance feeling. Results: Overall, the prototype insoles designed to offload focal pressure via removing modular cells showed significant immediate effects (all P ≤ 0.002). Averaged across both sides, average peak pressure (PP) of C2, C3 and C4 reduced from C1 by 19%, 25% and 28%, respectively; maximum PP of C2, C3 and C4 was reduced from C1 by 16%, 18% and 19%, respectively. With bilateral cavities, average PP at the second cavity side significantly decreased by a further 11% (C4 vs. C2, P = 0.003). These findings suggest that creating cavities alters the loading response during the gait cycle, as the metatarsal and heel peak pressures decreased. No imbalance was observed for C3 and C4. Participants reported satisfactory comfort and provided insights for future design development. Conclusion: This over-the-counter prototype shows potential for individuals to customise cavities in their insoles to manage excessive focal pressure.