人類足後跟軟組織層之機械性質

Mechanical Properties of the Human Heel Pad

足後跟軟組織層在行走或跑步當中，會降低地面對人體的反作用力、提供良好的避震效果(shock absorbency)，以減少全身骨骼肌肉的傷害。許多足跟疾病與足後跟軟組織層的機械性質改變具密切關係。目前有關足後跟軟組織層的機械性質之研究結論差異頗大，且無法於臨床上廣泛應用。因此本研究收集20位正常成年人（男10人，女10人)為測試對象，利用高頻率10MHz，直線形(linear array)超音波探頭與特製的壓縮－－還原裝置系統來測量足後跟軟組織層在承受不同壓力的厚度。超音波探頭下壓重量以0.5kg為單位，逐漸增加至3kg為止；再依次遞減下壓重量。根據下壓重量及足後跟軟組織層厚度的改變量做出“壓重－－形變”曲線；並算出能量散失百分比。測試所得平均足後跟軟組織層的厚度為1.7 ± 0.22cm，壓縮指數為50.41 ± 4.54%，能量散失百分比為6.52 ± 6.84%，硬度為3.58 ± 0.38kg/cm。兩腳的足後跟軟組織層厚度與體重呈強烈正相關。

During the gait cycle, the heel pad reduces the impact force from the ground and offers good shock absorbency to prevent injury to the musculoskeletal system. Changes of the mechanical properties of the heel pad may lead to heel pain syndrome. However, there are no conclusive data regarding the mechanical properties of the heel pad. We thus measured the thickness of the heel pad in 20 adult volunteers (10 men, 10 women with mean age of 29.68 ± 5.29) without heel lesions. Measurements were performed sonographically, with a 10-MHz linear array transducer. A specially designed compression-relaxation device with a push scale camped to the transducer was used to compress the heel pad. The heel pad was compressed by serial increments of 0.5 kg to a maximum of 3 kg, and then relaxed sequentially. The thickness of the heel pad under each loading condition was measured. The percentage energy dissipation during one loading and unloading cycle was calculated from the load-deformation curve. The mean (± SD) heel Pad thickness with no loading was 1.71 ± 0.22cm. The mean (± SD) percentage energy dissipation, compressibility index and stiffness were 26.52 ± 6.84%, 50.41 ± 4.54% and 3.58 ± 0.38 kg/cm, respectively. There was a strong positive correlation between heel pad thickness and body weight (r=0.60836, P= 0.0001).