目的探讨人工髋关节置换（total hip replacement,THR）前后慢走及上下楼梯两种不同步态下股骨的生物力学性能,为髋关节假体的优化设计和制造提供理论基础。方法建立人工髋关节股骨的三维有限元模型,并进行有效性验证;计算慢走和上下楼...目的探讨人工髋关节置换（total hip replacement,THR）前后慢走及上下楼梯两种不同步态下股骨的生物力学性能,为髋关节假体的优化设计和制造提供理论基础。方法建立人工髋关节股骨的三维有限元模型,并进行有效性验证;计算慢走和上下楼梯时THR前后股骨的应力分布及应力遮挡率。结果慢走运动时,THR前股骨应力由近端到远端逐渐递增,在股骨中下段达到最大,最大应力为90.6 MPa;THR后股骨出现应力遮挡现象,股骨的应力幅值有所下降,最大应力为82.5 MPa,股骨近端假体周围大转子附近股骨遮挡率最大,总体遮挡率为14.9%~99.0%。此外,假体颈部出现过大的应力集中现象。上下楼梯运动时,股骨应力分布的变化规律与慢走运动时大体相似,但应力遮挡效应更为明显。结论植入假体后,上下楼梯时股骨近端出现较大应力遮挡,并且假体自身出现过大应力集中,会影响THR手术质量,建议病人在术后应尽量减少关节角变化较大的运动。展开更多
Long-term loosening is the major cause of failure of arthroplasty. One of the major causes is stress shielding, initiated by the large stiffness difference between prosthesis and bone tissue. Therefore, prosthesis wit...Long-term loosening is the major cause of failure of arthroplasty. One of the major causes is stress shielding, initiated by the large stiffness difference between prosthesis and bone tissue. Therefore, prosthesis with reduced stiffness properties to match those of the bone tissue may be able to minimize such a problem. Design with porous structure is believed to reduce the stiffness of the prosthesis, however at the cost of decreased strength. In this study, a patient-specific bone-implant finite element model was developed for contact mechanics study of hip joint, and algorithms were developed to adjust the elastic modulus of elements in certain regions of the femoral stem, until optimal properties were achieved according to the pre-defined criterions of the strength and stability of the system. The global safety factor of the optimized femoral stem was 11.3, and 26.4% of elements were designed as solid. The bone volume with density loss was reduced by 40% compared to the solid stem. The methodology developed in this study provides a universal method to design a patient-specific prosthesis with a gradient modulus distribution for the purposes of minimizing the stress shielding effect and extending the lifespan of the implant.展开更多
The objective of this paper is to identify the effects of materials of cementless femoral stem on the functional adaptive behaviors of bone. The remodeling behaviors of a two-dimensional simplified model of cementless...The objective of this paper is to identify the effects of materials of cementless femoral stem on the functional adaptive behaviors of bone. The remodeling behaviors of a two-dimensional simplified model of cementless hip prosthesis with stiff stem, flexible ＇iso-elastic＇ stem, one-dimensional Functionally Graded Material （FGM） stern and two-dimensional FGM stem for the period of four years after prosthesis replacement were quantified by incorporating the bone remodeling algorithm with finite element analysis. The distributions of bone density, von Mises stress, and interface shear stress were obtained. The results show that two-dimensional FGM stem may produce more mechanical stimuli and more uniform interface shear stress compared with the stems made of other materials, thus the host bone is well preserved. Accordingly, the two-dimensional FGM stem is an appropriate femoral implant from a biomechanical point of view. The numerical simulation in this paper can provide a quantitative computational paradigm for the changes of bone morphology caused by implants, which can help to improve the design of implant to reduce stress shielding and the risk of bone-prosthesis interface failure.展开更多
文摘目的探讨人工髋关节置换（total hip replacement,THR）前后慢走及上下楼梯两种不同步态下股骨的生物力学性能,为髋关节假体的优化设计和制造提供理论基础。方法建立人工髋关节股骨的三维有限元模型,并进行有效性验证;计算慢走和上下楼梯时THR前后股骨的应力分布及应力遮挡率。结果慢走运动时,THR前股骨应力由近端到远端逐渐递增,在股骨中下段达到最大,最大应力为90.6 MPa;THR后股骨出现应力遮挡现象,股骨的应力幅值有所下降,最大应力为82.5 MPa,股骨近端假体周围大转子附近股骨遮挡率最大,总体遮挡率为14.9%~99.0%。此外,假体颈部出现过大的应力集中现象。上下楼梯运动时,股骨应力分布的变化规律与慢走运动时大体相似,但应力遮挡效应更为明显。结论植入假体后,上下楼梯时股骨近端出现较大应力遮挡,并且假体自身出现过大应力集中,会影响THR手术质量,建议病人在术后应尽量减少关节角变化较大的运动。
基金The work was supported by the funding from the program of the National Nature Science Foundation of China （Grant Nos. 51205303 and 51323007）, the pro- gram of Scientific and Technological Innovation in Shaanxi Province （Grant No. 2014KTZB01-02）, the Fundamental Research Funds for the Central Universities, and Research Fund for the Doctoral Program （RFDP） of Higher Education of China.
文摘Long-term loosening is the major cause of failure of arthroplasty. One of the major causes is stress shielding, initiated by the large stiffness difference between prosthesis and bone tissue. Therefore, prosthesis with reduced stiffness properties to match those of the bone tissue may be able to minimize such a problem. Design with porous structure is believed to reduce the stiffness of the prosthesis, however at the cost of decreased strength. In this study, a patient-specific bone-implant finite element model was developed for contact mechanics study of hip joint, and algorithms were developed to adjust the elastic modulus of elements in certain regions of the femoral stem, until optimal properties were achieved according to the pre-defined criterions of the strength and stability of the system. The global safety factor of the optimized femoral stem was 11.3, and 26.4% of elements were designed as solid. The bone volume with density loss was reduced by 40% compared to the solid stem. The methodology developed in this study provides a universal method to design a patient-specific prosthesis with a gradient modulus distribution for the purposes of minimizing the stress shielding effect and extending the lifespan of the implant.
基金This work is supported by the National Natural Science Foundation of China （Nos. 10832012, 10872061 and 10972090） and Scientific Advancing Front and Interdiscipline Innovation Project of Jilin University （No. 200903169）.
文摘The objective of this paper is to identify the effects of materials of cementless femoral stem on the functional adaptive behaviors of bone. The remodeling behaviors of a two-dimensional simplified model of cementless hip prosthesis with stiff stem, flexible ＇iso-elastic＇ stem, one-dimensional Functionally Graded Material （FGM） stern and two-dimensional FGM stem for the period of four years after prosthesis replacement were quantified by incorporating the bone remodeling algorithm with finite element analysis. The distributions of bone density, von Mises stress, and interface shear stress were obtained. The results show that two-dimensional FGM stem may produce more mechanical stimuli and more uniform interface shear stress compared with the stems made of other materials, thus the host bone is well preserved. Accordingly, the two-dimensional FGM stem is an appropriate femoral implant from a biomechanical point of view. The numerical simulation in this paper can provide a quantitative computational paradigm for the changes of bone morphology caused by implants, which can help to improve the design of implant to reduce stress shielding and the risk of bone-prosthesis interface failure.
文摘背景:胫骨远端粉碎性骨折伴软组织损伤的治疗具有挑战性,新型逆行胫骨髓内钉、外置接骨板是重要的治疗手段,但其在骨折愈合不同时期、不同负重情况时的骨折端应变、应力遮挡情况未见报道。目的:通过有限元分析法探讨骨折愈合不同时期逆行髓内钉及外置接骨板的生物力学差异,为临床应用及康复锻炼提供科学参考。方法:利用1名40岁健康男性的胫骨CT数据,建立胫骨远端粉碎骨折的有限元模型,构建胫骨逆行髓内钉、外置接骨板固定模型及骨痂模型并根据骨折的固定原则进行装配。使用ANSYS软件进行有限元分析,比较骨折愈合不同时期时逆行髓内钉及外置接骨板2种固定方式的骨折端位移、胫骨应力遮挡、骨痂应力、胫骨及固定装置应力分布情况。结果与结论:①胫骨骨折端相对位移随着骨折愈合的进行逐渐减小,在术后3个月后位移明显减少;术后0,1个月,外置接骨板组的垂直位移及总位移均大于逆行髓内钉组,2种固定方式的Z轴位移(水平内外侧位移)均较X、Y轴位移明显,且接骨板模型的Z轴位移差异最明显;2种固定方式的Z轴位移最大位置均位于胫骨外侧,位移最小位置均位于胫骨内侧;②骨折愈合的应力遮挡率随骨折时间延长而逐渐降低;逆行髓内钉的应力遮挡率在骨折愈合不同时期均高于外置接骨板;术后3个月后外置接骨板的应力遮挡率降低到4%左右,逆行髓内钉的应力遮挡率降低到40%左右;③2种固定方式骨痂应力集中部位的应力随着载荷的增大而增加,外置接骨板组骨痂的应力始终大于逆行髓内钉组;2种固定方式中,骨痂最大应力大致分布一致,均位于胫骨外侧部分;④随着骨折愈合2种固定方式的胫骨最大应力逐渐降低,外置接骨板组的应力始终大于逆行髓内钉组;1500 N载荷下外置接骨板组胫骨最大应力区域平均应力为285 MPa,而逆行髓内钉组为26 M
