老龄骨退化机理及振动促进骨折愈合的多尺度实验研究

发布时间：2018-06-01 02:25

本文选题：老龄 + 区域退化　；参考：《吉林大学》2015年博士论文

【摘要】：通过了解老龄股骨颈骨折患者的股骨头松质骨不同区域骨材料纳观表面形态和力学性能，探讨股骨头不同区域骨材料的老龄化过程和材料属性，为降低临床股骨颈骨折内固定术失败率及探索老龄脆性骨折机理提供理论依据。同时观测了骨折愈合过程中骨的显微结构，骨质材料属性分布的变化，及其与宏观和微观力学性能之间的关系，探讨不同间歇方式的高频率低载荷机械振动（LMHFV）对骨折愈合的影响，为临床寻找合适的促进骨折愈合的物理方法提供理论基础。第一部分，选取女性股骨颈骨折后的股骨头样本10个，划分为老龄（65-66岁）和高龄（85-95岁）两个组别，每组5个样本。将股骨头沿冠状面划分为前（Ant）、中（Cen）、后（Pos）三个层面，每个层面划分上（S）、中（C）、下（I）、内（M）、外（L）5个区域，分别采用原子力显微镜（AFM）和纳米压痕仪对每个区域骨小梁的横向和纵向纳观表面形态和力学性能进行检测。从整体、不同层面和不同区域三个角度探讨老龄股骨头骨小梁随年龄的退化过程。结果表明，无论从股骨头整体，还是不同层面、不同区域上看，均未发现骨小梁表面颗粒度和粗糙度随年龄的显著变化。可见绝经后女性骨小梁纳观形态不足以提供与骨折或骨质量下降相关的差异性。在老龄股骨头整体骨小梁退化方向上，纵向显著快于横向；前面层退化程度较其他两个层面偏快；在拉应力为主的区域（内，外侧），其纵向力学性能的退化程度均高于其它3个区域，且纵向的退化均快于横向。第二部分，建立小尾寒羊的胫骨骨折模型，于骨折后4、8、12周分批处死，分别对伤侧含骨痂胫骨部分和健侧对应部分进行影像学评估和Micro-CT扫描，获得显微结构形态参数，建立伤侧和健侧显微有限元模型，施加5%宏观应变，计算得到宏观及微观力学参数。利用主元素分析法在骨质材料属性分布和显微结构参数中提取最能反应骨力学性能改变的主元素，并通过主元素与力学性能的线性回归分析，建立他们之间的关系。结果表明，骨折模型建立4周时即可观察到骨痂的生长，在8周时观测到伤侧弹性模量愈合百分比的增加，而到达12周后组织平均von Mises应力才出现大幅度增大。通过对显微结构参数与骨质材料属性分布的主元素分析得到了三个主元素，其累计贡献率为87.60%，线性回归结果表明，三个主元素线性拟合宏观弹性模量和组织平均von Mises应力具备统计学意义（P0.05）。可见，，随着骨折愈合进程的延续，含骨痂胫骨部分的力学性能明显增加，基于Micro-CT的显微有限元分析可以有效预测骨强度。骨折愈合过程中，骨质的材料属性分布与显微结构参数可以有效预测骨结构力学性能，反映骨折愈合进程中骨组织重建的过程，对进一步探索骨折愈合机理具有一定意义。第三部分，选取大鼠35只，建立双侧胫骨横行骨折模型，克氏针内固定。大鼠随机分为5组，持续振动组（DL组，每天给予15分钟LMHFV）；持续分次振动组（DLR组，每天施加LMHFV，每天3次，每次5分钟，每2次振动实验之间间隔4小时）；间歇7天振动组（VL7组，振动7天，休息7天，振动期间，每天1次LMHFV，每次15分钟）；间歇7天分次振动组（VL7R组，振动7天，休息7天，振动期间分次振动方法同DLR组）和骨折对照组（FBC组）。大鼠骨折模型建立1周后开始实施振动实验，振动频率35Hz，加速度0.25g。实验4周后，大鼠过麻处死，分别进行胫骨三点弯曲实验、纳米压痕测试、原子力显微镜观测，Micro-CT扫描、组织形态学观察以及血清骨钙素（OG）和抗酒石酸酸性磷酸酶（TRAP5b）检测。结果表明：宏观力学性能上，无论是破坏载荷还是弹性模量，DL组和DLR组都显著高于FBC组（P0.05）；纳观力学性能上，DLR组在压痕模量和硬度上均体现了最大值，且显著高于FBC组（P0.05），同时DL组和VL7组硬度显著高于FBC组（P0.05）。BMD分析显示，DLR组和VL7组体现了较高的骨密度值，显著高于FBC组（P0.05）。Micro-CT扫描获得的微观结构参数未发现各组间显著差异。AFM检测未观测到颗粒度的明显差异，而粗糙度DLR组最大，且显著高于FBC组（P0.05）。血清生化检测未发现各组间OG的显著差异，FBC组TRAP5b显著高于振动各组（P0.05）。可见，高频率低载荷机械振动不仅在力学性能上（宏观和纳观）体现了其对骨折愈合进程的促进作用，同时显著影响了微观骨密度（BMD）和骨材料在纳观空间排布（粗糙度），其中以持续并分次的振动方式（DLR组）对骨折愈合的促进作用最为明显。可见在这一模式下，振动对骨折愈合的促进效果既达到了成骨累积，又使骨细胞力学敏感性得到了充分的恢复，具备很大的临床应用潜力。
[Abstract]:The aging process and material properties of bone materials in different regions of the femoral head are discussed by understanding the surface morphology and mechanical properties of the bone materials in different regions of the femoral head of the aged femoral neck fracture. The theoretical basis for reducing the failure rate of internal fixation and exploring the mechanism of the aging brittle fracture is provided. The microstructure of bone, the change of the distribution of bone material properties and the relationship with the macroscopic and micromechanical properties were measured during the fracture healing process, and the effect of high frequency and low load mechanical vibration (LMHFV) on fracture healing was discussed in different intermittent ways, and the theoretical basis for finding a suitable physical method for promoting fracture healing was provided.
In the first part, 10 femoral head samples of femur neck fracture were selected and divided into two groups of aged (65-66 years old) and age (85-95 years old), each group was divided into 5 samples. The femoral head was divided into front (Ant), middle (Cen), and then (Pos) three layers, each layer was divided (S), middle (C), I, M, and outer (L) 5 regions, respectively. The transverse and longitudinal nanoscale surface morphology and mechanical properties of the bone trabecula in each region were detected by AFM and nanoindentation. The degradation process of the aged bone trabecular bone trabecula with the age was investigated from three angles, including the whole, the different layers and the different regions. There was no significant change in the grain size and roughness of the bone trabecular surface with age. It was found that the postmenopausal women's bone trabecular nanoscale morphology was not enough to provide the difference with the reduction of fracture or bone mass. In the direction of the degradation of the whole bone trabecula in the aged femoral head, the longitudinal direction was significantly faster than that in the transverse direction; the degree of degeneration in the front layer was more than the other two levels. Fast, in the tensile stress region (inside, outside), the longitudinal mechanical properties of the degradation degree is higher than the other 3 regions, and the longitudinal degradation is faster than the transverse.
In the second part, the model of tibial fracture of Small Tail Han sheep was established. After 4,8,12 weeks after the fracture, the images of the tibial part of the callus and the corresponding part of the injured side were evaluated by imaging and Micro-CT scanning respectively. The morphological parameters of the microstructures were obtained. The microscopic model of the injured side and the healthy side was established, and the macroscopic strain was applied to the macroscopic strain, and the macroscopic and the macroscopic strain was calculated. The principal element analysis method is used to extract the main elements which can reflect the changes of bone mechanical properties most in the properties of bone material properties and microstructure parameters. The relationship between the main elements and the mechanical properties is analyzed by linear regression analysis. The results show that the fracture model can be observed at 4 weeks. The percentage of the modulus of healing of the elastic modulus of the injured side increased at 8 weeks, and the average von Mises stress of the tissue increased greatly after 12 weeks. Three main elements were obtained by the analysis of the main elements of the microstructure parameters and the distribution of the properties of the bone material. The cumulative contribution rate was 87.60%. The linear regression results showed that three main elements lines were found. The macroscopic modulus of elasticity and the average von Mises stress of the tissue are statistically significant (P0.05). It is visible that the mechanical properties of the tibial part of the callus increase obviously with the continuation of the fracture healing process, and the bone strength based on the microscopic finite element analysis based on Micro-CT can be effectively predicted. The distribution of the material properties of bone in the process of bone fracture healing and the apparent distribution of bone material The microstructural parameters can effectively predict the mechanical properties of bone structure and reflect the process of bone tissue reconstruction in the process of fracture healing, which is of certain significance for further exploration of the mechanism of fracture healing.
The third part, 35 rats were selected to establish the bilateral tibial transverse fracture model and Kirschner pin internal fixation. The rats were randomly divided into 5 groups, the continuous vibration group (group DL, 15 minutes LMHFV per day); the continuous fractionation group (group DLR, 3 times a day, 5 minutes each day, 4 hours each 2 vibration experiments), and the intermittent 7 days vibration group (VL7 Group, vibration 7 days, rest 7 days, 1 times a day, 1 times a day, 15 minutes each time, 15 minutes each time, 7 days of intermittent vibration group (group VL7R, vibration 7 days, rest 7 days, vibration during the same group DLR group) and fracture control group (group FBC). Rats fracture model was established after the establishment of vibration experiment, vibration frequency 35Hz, acceleration 0.25g. Experiment 4 weeks later, Rats were killed by hemp, the three point bending test of tibia, nano indentation test, atomic force microscope observation, Micro-CT scan, histomorphology observation, Serum Osteocalcin (OG) and tartrate acid acid phosphatase (TRAP5b) were detected. The results showed that the macroscopic mechanical energy was on the damage load or modulus of elasticity, DL and DLR groups. Both significantly higher than the FBC group (P0.05), the maximum of the modulus and hardness of the DLR group was reflected in the mechanical properties of the DLR group, and was significantly higher than that in the FBC group (P0.05), and the hardness of the DL and VL7 groups was significantly higher than that of the FBC group (P0.05).BMD analysis, and the higher bone density was shown in the DLR group and the VL7 group. The microscopic structure parameters did not find significant differences between the.AFM detection and the significant difference in the granularity, while the roughness DLR group was the largest and significantly higher than that of the FBC group (P0.05). The serum biochemical test did not find the significant difference between the OG in each group, and the FBC group TRAP5b was significantly higher than that of the vibration group (P0.05). The high frequency and low load mechanical vibration is not only in the force of the mechanical vibration, but the mechanical vibration of the high frequency and low load is not only in the force. The learning performance (macroscopical and observational) reflects the promotion of fracture healing process, and it also significantly affects the microcosmic bone mineral density (BMD) and bone material in the nanoscale space (roughness), in which the continuous and fractionated mode of vibration (group DLR) promotes the healing of fracture most obviously. The promoting effect of the combination not only achieves the accumulation of bone, but also fully restores the mechanical sensitivity of bone cells, so it has great potential for clinical application.
【学位授予单位】：吉林大学
【学位级别】：博士
【学位授予年份】：2015
【分类号】：R687.3

【共引文献】