The Movement Function Decline In The Foot Of The Elderly:A Mechanical Perspective

In this thesis, the elderly over 60 years were taken as the test group mainly in the regions of Shanghai, Shaanxi in China. Some of them were from Jiangsu Zhejiang Henan Hebei. And the reference group was consist of young people in 20-26. Through three aspects of study, the subjective and objective results were combined to explore the mechanics of movement function decline of the foot of the elderly.The first research was the survey of questionnaire and foot morphological images. A convenient sample of 1000 questionnaires about the problems of foot and footwear were released and 800 valid questionnaires were recovered. Foot images of the elderly were collected by HD camera. The second research was the study of foot types. The foot length, width and girth of foot types of a sample of 271 elderly people were measured using Footprint Collector to obtain the foot types of the elderly. The third research was the movement biomechanics of the foot of 58 elderly people with healthy feet. The plantar pressure of the elderly were obtained using Footscan7.0 flat plantar pressure test system. The gait characteristics of the elderly were obtained using Kistler three-dimensional force platform test system. The sEMG of the muscles in the lower limbs of the elderly were obtained using Biovision8 wireless surface electromyography system. The parameters of time domain and frequency domain were used to analyze the characteristics and the impacts to the function of muscles with the varieties of these parameters in different walking stage. Statistical analyses were performed using the SPSS system 19.0 and Excel software. The t-test for independent samples was applied to determine whether differences in the foot types between the elderly and the adults in China were significant. The significant level was taken to be Sig. (2-tailed)<0.05.The results showed that:(1) There were diseases and deformations of the foot morphological of the elderly. The results of the foot diseases in the elderly showed that 89% of the elderly have foot lesions, which mainly were skin agings and nail lesions. The results showed that 86.75% of the elderly have deformations in China. And the deformations were mainly the distortion of the phalanges joints and toe-metatarsal joints. It showed that 50% of the elderly have flat foot.(2) The results of foot types showed that length and width of the foot type of the elderly increased, girth of the foot type of the elderly declined. Foot width of the elderly increased significantly (Sig.2-tailed<0.01) with 1.5-2 type for elderly female and 2.5-3 type for elderly male.(3) The results of defect measurement showed that 47% of the elderly had hallux valgus, and hallux valgus angle in 15-20 degrees accounted for 22.8% in elderly male and 23% in elderly female. The results of the ratio of the width of the footprints to that of foot contour showed 89% of the elderly had the ratio over 1/3. And the ratio range 40%-60% was the most common foot arch. There were 96.25% of the elderly who had callus in foot plantar. And the number of the callus was 2-3 usually.(4) Compared to the foot pressure of the adults all around China, the foot pressure of the elderly showed that peak pressures in the regions of M2, M3 of forefoot and HM, HL of heel have increased, as well as the force impulse in the same regions. And that indicated elderly people had the motor dysfunction characteristics of foot fatigue easily. The results of contact area and force impulse in the region of HF showed that most elderly people had flat foot and a weary feel in their feet.(5) The 3D force, and phase time, and media-lateral COP showed that elderly people had toe-out gait, slower step speed, procrastinating gait, smaller step amplitude, lacking strength to lift foot and high risk of fallen.(6) The parameters of time domain and frequency domain of sEMG test system showed that the lower limbs of the elderly were easily to generate fatigue.