人工全髋关节置换术对天然股骨生物力学行为的影响

目的研究人工全髋关节置换术后股骨的变形及应力改变,同时研究关节置换术对股骨振型及固有频率的影响。方法选取1名正常男性青年进行股骨段CT扫描,构建正常股骨和术后股骨的有限元模型,对其进行步态情况下的生物力学行为分析、模态分析。结果 (1)关节置换术后假体柄部有明显的应力集中,并产生了应力遮挡;(2)术后股骨的峰值应力增大到原来的4.36倍;(3)约束模态的固有频率明显高于自由模态;(4)振型阶次越高,术后股骨与正常股骨固有频率的差距越大;(5)股骨的振型主要为弯曲和扭转,且置换前后振型变化不大。结论假体的植入改变了股骨原有的力学结构特性。在假体设计方面,必须考虑到股骨的振动特性,避免共振带来的假体松动。

Effect of total hip arthroplasty on biomechanical behavior of natural femur

Objective To study the deformation and stress distribution of femur after total hip arthroplasty (THA) and its influence on the vibration mode and natural frequency of femur. Method Two finite element models of natural femur and femur after THA were developed on the basis of computed tomography (CT) scans from a normal young man to investigate the biomechanical behavior of the subjectunder gait condition and make the modal analysis. Results (1) After THA, obvious stress concentration was obtained around the prosthesis neck, and the stress shielding was observed; (2) The peak stress of femur model after THA increased to 4.36 times of the original one; (3) The natural frequency for constrained mode was much higher than that of free mode; (4) With the increase of vibration mode, the differences in natural frequency between two models became larger; (5) Bending and twisting were the main vibration mode of femur, and there were no significant changes in vibration mode before and after THA. Conclusions The prosthesis could change the mechanical and structural properties of the original femur. In order to avoid prosthesis loosening derived from sympathetic vibration, the vibration property of femur must be taken into consideration in the design of prosthesis.