基于尺桡骨三维有限元模型分析桡骨远端骨折的生物力学特征

Biomechanical characteristics of the distal radius fracture based on three-dimensional finite element model of ulna and radius

背景:近年来关于桡骨远端骨折机制偏向定性的研究多数仅限于二维分析,易受多种因素影响,导致结果不甚满意,而利用CT数据建立三维有限元模型可更好评估人体骨骼变异情况。目的:通过建立尺桡骨三维有限元模型,检测桡骨远端骨折生物力学,并进行桡骨远端骨折发生机制研究。方法:获取1名50岁健康女性左侧上肢肱骨远端到腕关节中段CT扫描影像学资料,志愿者对试验方案知情同意,且经CT扫描显示正常,排除患有骨科相关疾病。利用三维有限元分析软件Ansys 16.0建立尺桡骨三维有限元模型,模拟手腕背伸、掌屈、尺偏、桡偏时力的加载,观察记录不同载荷下模型各部分应力;分析不同模型角度时桡骨远端骨折形成及裂纹走向。结果与结论:①腕关节处于背伸位时,前臂旋前和前臂旋后桡骨背侧缘中点受压应力,随背伸角度增大而增大;前臂旋前和前臂旋后桡骨掌侧受张应力,随背伸角度增大而增大;②腕关节处于掌屈位时,前臂旋前和前臂旋后桡骨背侧缘中点受张应力,随掌屈角度增大而增大;前臂旋前和前臂旋后桡骨掌侧受压应力,随掌屈角度增大而增大;③前臂旋前背伸位及前臂旋后掌屈位时,桡骨裂纹首先出现于松质骨与密质骨交界处桡骨远端表面受最大张力一侧,骨折裂纹沿掌远端向近背端,与骨轴线45°角方向发展;④前臂旋前掌屈位及前臂旋后背伸位时,桡骨裂纹首先出现于松质骨与密质骨交界处桡骨远端表面受最大张力一侧,骨折裂纹沿远背端向近掌侧,与骨轴线45°角方向发展;⑤结果表明,手腕背伸、掌屈、尺偏、桡偏进行力的加载,骨折首先出现于松质骨与密质骨交界处桡骨远端表面受最大张力一侧,裂纹走向与所受应切力和张应力方向有关。

BACKGROUND: In recent years, most qualitative studies on the mechanism of distal radius fracture are limited to two-dimensional analysis, which is susceptible to many factors, resulting in unsatisfactory results. The use of CT data to establish a three-dimensional finite element model can better evaluate human skeletal variation. OBJECTIVE: To establish a three-dimensional finite element model of the radius and ulna, to test the biomechanics of distal radius fracture and to study the mechanism of distal radius fracture. METHODS: Left upper limb of one 50-year-old healthy female was selected to obtain CT imaging data from distal humerus to middle carpal joint. The three-dimensional finite element model of radius and ulna was established by using three-dimensional finite element analysis software Ansys 16.0. The force load of wrist back extension, palm flexion, ulnar deviation, and radial deviation were simulated. The stress of each part of the model under different loads was observed and recorded. The fracture formation and crack direction of distal radius at different model angles were analyzed. RESULTS AND CONCLUSION:(1) When the wrist joint was in dorsal extension position, the compressive stress at the midpoint of the dorsal radial margin of the forearm pronation and forearm supination increased with the increase of the dorsal extension angle, the tension stress on the volar radius of the forearm pronation and forearm supination increased with the increase of the dorsal extension angle.( 2) When the wrist joint was in the metacarpal flexion position, the tension stress at the midpoint of the dorsal radius of the forearm pronation and the forearm supination increased with the increase of the metacarpal flexion angle. The compressive stress on the volar radius of the for earm pronation and forearm supination increased with the increase of the palmar flexion angle.(3) When the forearm was pronated dorsiflexion and supinated metacarpal flexion, the radial crack first appeared on the side of the maximum tension on the surface of the distal radius at the junction of cancellous bone and dense bone, the fracture crack developed along the distal metacarpal to the proximal dorsal end and at an angle of 45 degrees to the bone axis.(4) When the forearm was pronated metacarpal flexion and supinated dorsiflexion, the radial crack first appeared on the side of the maximum tension on the surface of the distal radius at the junction of cancellous bone and dense bone, the fr acture crack developed along the far back end to the proximal palmar side and at an angle of 45 degr ees to the bone axis.(5) To conclude, with the force load on wrist dorsal extension, metacarpal flexion, ulnar deviation, and radial deviation, the fracture first occurs on the m aximum surface tension side of the distal radius at the junction of cancellous bone and dense bone, the direction of the crack is related to the directions of shear stress and tension stress.