论文题目：长骨类骨折内固定系统刚度和应力分布规律及骨板刚度确定方法

摘要:

目的 研究由断骨（含骨痂）和骨板组成的长骨类骨折内固定系统中各组成部分刚度和应力的分布规律，提出骨折内固定植入物抗弯刚度确定方法。方法 基于线性弯曲理论与复合梁理论，构建由断骨-骨板组成的股骨干骨折内固定系统的力学模型，以基于人造股骨CT数据的有限元模型进行验证，建立长骨类骨折内固定系统应力和刚度的关系式。结果 通过计算分析得到的断骨抗弯刚度随骨痂弹性模量变化的三个阶段（缓慢增长-快速增长-平稳增长）与实际骨骼愈合过程中的三个阶段的情况相符，证明理论计算方法的准确性；进一步得到断骨-骨板组成的骨折内固定系统中性轴位置的变化规律，即提高（降低）骨板的刚度可使中性轴的位置向骨板中心轴靠近（远离）；根据骨折愈合所需的应力大小（0.72~0.8MPa），得到骨板抗弯刚度的合理范围为990~4200 N·mm2。结论 1）骨痂弹性模量为0.03~7GPa时，断骨抗弯刚度快速上升，是骨桥的生成阶段；骨痂弹性模量为7GPa以上时，骨痂趋于成熟。2）基于本文的股骨模型，当骨板厚度约为3.6~6mm，且断骨的弹性模量约为3~13.5GPa时，可使整个断骨截面受到有效的力学刺激。3）本文的研究对象在骨桥的生成阶段，接骨板的抗弯刚度为990~4200 N·mm2时有利于骨愈合。

关键词:骨折内固定系统;刚度;应力分流;复合梁理论;骨愈合

Abstract:

Objective To study the distribution of stiffness and stress of each component in the internal fixation system for long bone fractures composed of broken bones (including callus) and bone plates，proposed a method for determining the flexural rigidity of fracture internal fixation implants. Methods Based on the linear bending theory and the composite beam theory, the mechanical model of the femoral shaft internal fracture-fixing system composed of broken bone and bone plate is constructed and verified with a finite element model based on artificial femur CT data. Finally, the relationship between stress and stiffness of the internal fixation system for long bone fractures is established. Results The three stages (slow growth-rapid growth-steady growth) of the bending stiffness of the broken bone obtained by calculation and analysis with the elastic modulus of the callus are consistent with the three stages of the actual bone healing process, which prove the accuracy of theoretical calculation methods. Further obtain the change rule of the neutral axis position of the fracture internal fracture-fixing system composed of broken bone and bone plate, increasing (decreasing) the rigidity of the bone plate can make the position of the neutral axis approach (away) to the central axis of the bone plate. According to the stress required for fracture healing (0.72~0.8MPa), the reasonable range of flexural rigidity of the bone plate is 990~4200 N·mm2. Conclusions 1) When the elastic modulus of the callus is 0.03~7GPa, the flexural rigidity of the broken bone rises rapidly, which is the stage of bone bridge formation. When the elastic modulus of the callus is above 7GPa, the callus tends to mature. 2) Based on the femur model in this article, when the thickness of the bone plate is about 3.6-6mm and the elastic modulus of the broken bone is about 3~13.5GPa, the entire fractured bone section can be effectively stimulated. 3) The research object of this article is in the generation stage of the bone bridge, when the bending stiffness of the bone plate is 990~4200 N·mm2, it is conducive to bone healing.

Key words:internal fracture-fixing system; stiffness; stress shunt; composite beam; bone healing