Hsu T C, Wang C L, Tsai W C, Kuo J K, Tang F T
Department of Rehabilitation Medicine, Chang Gung Memorial Hospital, Chang Gung University, Gueishan, Taoyuan Hsien, Taiwan.
Arch Phys Med Rehabil. 1998 Sep;79(9):1101-4. doi: 10.1016/s0003-9993(98)90178-2.
To compare the mechanical properties of the human heel pad between young and aged adults.
A 7.5-MHz linear-array ultrasound transducer was incorporated into a specially designed device to measure the thickness of the heel pad under different loads. The heel pad was compressed with serial increments of 0.5kg to a maximum of 3kg and then relaxed sequentially. Then the load-displacement curve of the heel pad during a loading-unloading cycle was plotted.
Convenience sample of 33 volunteers without heel problems, aged 18 to 78 years, were divided into young (less than 40 years) and elderly (older than 60 years) groups.
Unloaded heel-pad thickness, compressibility index, stiffness, and energy dissipation ratio were calculated from the load-displacement curves. Student's t-test was used to compare the mechanical properties of the heel between these two groups.
The average unloaded heel-pad thickness was 1.76+/-.20cm in the young group and 2.01+/-.24cm in the elderly group (p < .001). The average compressibility index was 53.3%+/-7.7% in the young group and 61.3%+/-5.5% in the elderly group (p < .001). Energy dissipation ratio representing shock absorbency of the heel pad, was 23.7%+/-6.9% in the young group and 35.3%+/-10% in the elderly group (p < .001).
Unloaded heel-pad thickness, compressibility index, and energy dissipation ratio of the heel pad were significantly increased in the elderly group, indicating loss of the elasticity of the heel pad. The loss of elasticity may be responsible for the higher incidence of heel injury in elderly individuals.
比较年轻人和老年人足跟垫的力学性能。
将一个7.5兆赫的线性阵列超声换能器集成到一个专门设计的装置中，以测量不同负荷下足跟垫的厚度。足跟垫以0.5千克的连续增量压缩至最大3千克，然后依次放松。然后绘制加载-卸载循环期间足跟垫的负荷-位移曲线。
33名无足跟问题的志愿者组成的便利样本，年龄在18至78岁之间，分为年轻组（小于40岁）和老年组（大于60岁）。
根据负荷-位移曲线计算无负荷足跟垫厚度、压缩指数、硬度和能量耗散率。采用学生t检验比较两组足跟的力学性能。
年轻组平均无负荷足跟垫厚度为1.76±0.20厘米，老年组为2.01±0.24厘米（p<0.001）。年轻组平均压缩指数为53.3%±7.7%，老年组为61.3%±5.5%（p<0.001）。代表足跟垫减震能力的能量耗散率，年轻组为23.7%±6.9%，老年组为35.3%±10%（p<0.001）。
老年组足跟垫的无负荷厚度、压缩指数和能量耗散率显著增加，表明足跟垫弹性丧失。弹性丧失可能是老年人足跟损伤发生率较高的原因。
