2023, Vol. 27 ›› Issue (13): 2005-2010

Plantar pressure at different phases during gait cycle in diabetic patients and midsole structure design

Cao Zijun1, 2, Wang Fang1, 2, Li Xuemei3, Li Mingxin4, He Yaoguang1, 2, Zhang Yu1, 2, Yang Tao1, 2, Liu Guoqing1, 2, Zhang Jianguo1, 2   

Abstract: BACKGROUND: High plantar pressure is one of the critical factors causing diabetic foot ulcers. Studying the plantar pressure in multi-phase during gait cycle of diabetic patients contributes to offloading footwear development.  
OBJECTIVE: To analyze the plantar pressure distribution in diabetic patients at heel strike and push off, and design midsole to optimize offloading effect.
METHODS: Plantar pressure was tested to analyze the difference in plantar pressure at heel strike and push off between diabetics patients with diabetic peripheral neuropathy and without diabetic peripheral neuropathy and healthy subjects. Finite element model of foot was constructed. Ethylene vinyl acetate copolymer midsole and thermoplastic polyurethane diamond lattice structure midsole with different modulus were designed. Changes in plantar pressure and stress of soft tissue at heel strike and push off in diabetic peripheral neuropathy patient were analyzed to optimize the structure size of diabetes footwear.  
RESULTS AND CONCLUSION: (1) The peak plantar pressure at push off in diabetic peripheral neuropathy group (22.2%)   was higher than healthy control group (P < 0.05). (2) Ethylene vinyl acetate copolymer midsole reduced the peak plantar pressure at heel strike and push off by 13.0% and 12.9%, reduced the peak stress of soft tissue at two phases by 18.2% and 11.1%. (3) The optimized diamond lattice structure reduced the peak plantar pressure at two phases by 41.6% and 48.4%, reduced the peak stress of soft tissue at two phases by 41.4% and 49.8%. (4) In conclusion, offloading at push off should be noticed in development of diabetic footwear. The diamond lattice structure midsole could archive better effect than ethylene vinyl acetate copolymer midsole.
Key words: diabetes, plantar pressure, gait, biomechanics, finite element analysis, footwear, midsole, lattice structure