人体股骨冲击特性数值模拟

Numerical modeling of impact character in human femur

目的:考察人体步态运动过程中冲击载荷作用时的应力和变形分布。方法:①2005-08-31在徐州医学院附属医院通过美国GE公司HispeedNx/i型双层螺旋CT对一志愿者(年龄28岁,身高173cm,体质量60kg)的股骨进行扫描,获得DICOM格式图像数据,采用逆向工程方法生成实体模型。②将三维模型导入有限元分析软件(Ansys8.0),单元选择Solid45,骨密质的弹性模量选择为16.7GPa,泊松比0.3。③对股骨进行远端固定,模拟股骨在膝关节完全固定情况(人体站立相)下的静力影响,同时采用冲击载荷对股骨进行试验,比较冲击载荷对股骨的不同作用效果,以及股骨在冲击载荷作用下的力学特性。结果:①在200N载荷作用下静载的峰值应力大于冲击载荷作用(847.451MPa比308.511MPa),从分布区域看,静载的峰值应力主要集中在股骨干部分,位置接近于远端1/3处,而冲击载荷峰值分布于股骨颈周围区域。②股骨在受到2546.04N冲击载荷作用后,股骨颈下部是应力响应的敏感区域,随着与冲击区域距离的增加,应力响应逐渐变小,除股骨近端1/3处外其他各处响应均迅速下降。③应力值随着冲击载荷的增大而增大,载荷为2063.88N,2546.04N时最大应力区均集中在股骨颈的下侧面,但当冲击载荷达到2728.32N时最大应力区超出颈部区域,出现在小转子外侧的股骨干上,且应力分布峰值区域变大。结论:①在低冲击载荷作用下,高应力区出现在股骨颈附近区域,随着载荷的增加,破坏区域从单纯的骨股颈区域扩展到了小转子外下侧的股骨干区域。②对比临床,股骨颈和小转子外下侧股骨干部分也是可能导致骨折的区域。

AIM： To determine the stress and strain distribution of femur under impact force during human gait cycle. METHODS：①A volunteer （28 years, 173 cm, 60 kg） femur was scanned by double-helix CT of HispeedNx/i type made in GE co.ltd USA in Affiliated Hospital of Xuzhou Medical College on August 31^st, 2005. Entity model was developed through DICOM image data gain by scan. ②The model was opened in finite element software （Ansys 8.0） and solid45 was selected as element. Elastic module of cortical bone was 16.7 GPa, and poisson＇s ratio was 0.3. ③The distal end of femur was fixed to simulate the impact of static force under standingman condition and femur was measured under impact force. Different effects of impact force on femur and the mechanism character of femur under impact force were compared. RESULTS： ①The peak stress under 200 N static force more than impact force （847.451 Mpa vs 308.511 MPa）. The stress range of static concentrated at femur location adjacent to 1/3 distal end. The stress range under impact force was distributed in femur neck. ②Under 2 546.04 N impact force, femur neck was the sensitivity area of stress response. The stress response decreased with distance increasing to impact region, except 1/3 proximal end of femur, ③The magnitude of stress increased with impact force enhanced. Max-stress range concentrated underside of femur neck under 2 063.88 N and 2 546.04 N impact force. However, the max- stress range, under 2 728.32 N impact force, concentrated lateral shaft of femur of the lesser trochanter and range larger than other. CONCLUSION： ①High stress range assembles femur neck under small impact force, and breakage district changes from simple femur neck into inferolateral shaft of femur of the lesser trochanter with the increase of force. ② According to the clinical experience, the femur neck and inferolateral shaft of femur of the lesser trochanter are all the catagmatic range.