Li Yu, Fei Han, Wang Jun, Li Ting, Feng Yihui, Huan Yong
State Key Laboratory of Nonlinear Mechanics (LNM), Institute of Mechanics, Chinese Academy of Sciences, Beijing 100190, China; School of Engineering Science, University of Chinese Academy of Sciences, Beijing 100049, China.
Department of Traumatic Orthopedics, Beijing Jishuitan Hospital, Beijing 100035, China.
J Biomech Eng. 2022 Apr 1;144(4). doi: 10.1115/1.4052884.
Stress shielding is an important factor in the internal fixation of a fracture. To explore the regularity of stress shielding in internal fixation, a simplified model of a comminuted femoral shaft fracture bridged by a locking plate was established and finite element analysis was performed to analyze the load distribution between the plate and femur from the proximal end of the femur to the fracture line and investigate the stress shielding degree of the plate on the bone. The stress, deformation, and axial compressive force distribution of four internal fixation schemes under compression were obtained, and the stress shielding degrees on each section was calculated. To compare the regularity of stress shielding and flow distribution, the relationship between the compressive force increment and stress shielding degree was established. The normalized curves of compressive force increment with the plate section position were compared with the flow distribution in a Z-type manifold, a parallel pipe system similar to an internal fixation system in structure and working characteristics. For quantitative comparison, the similarity between normalized curves of the compressive force increment and simulated flow distribution was calculated. The regularity of load distribution along the section position of the plate was similar to the flow distribution in the Z-type manifold. Therefore, the flow distribution pattern of the Z-type manifold can be used to characterize the regularity of load distribution in internal fixation. This study provided a new method to characterize the stress shielding degree of a locking plate on bone.
应力遮挡是骨折内固定中的一个重要因素。为探究内固定中应力遮挡的规律，建立了一个由锁定钢板桥接的股骨干粉碎性骨折简化模型，并进行有限元分析，以分析从股骨近端到骨折线处钢板与股骨之间的载荷分布情况，并研究钢板对骨的应力遮挡程度。获得了四种内固定方案在压缩状态下的应力、变形及轴向压缩力分布，并计算了各截面处的应力遮挡程度。为比较应力遮挡规律与血流分布规律，建立了压缩力增量与应力遮挡程度之间的关系。将压缩力增量随钢板截面位置的归一化曲线与Z型歧管中的血流分布进行比较，Z型歧管是一种在结构和工作特性上与内固定系统相似的平行管道系统。为进行定量比较，计算了压缩力增量归一化曲线与模拟血流分布之间的相似性。沿钢板截面位置的载荷分布规律与Z型歧管中的血流分布相似。因此，Z型歧管的血流分布模式可用于表征内固定中载荷分布的规律。本研究提供了一种表征锁定钢板对骨应力遮挡程度的新方法。
