拇外翻足有限元模型构建及其第1跖趾关节生物力学分析

Construction of finite element model of hallux valgus foot and biomechanical analysis of the first metatarsophalangeal joint

背景:有限元模型构建及生物力学分析使探究拇外翻足的形成及相关结构功能恢复成为可能。目的:建立负重中立位中度拇外翻足有限元模型,分析不同部位及大小的外力作用下第1跖趾关节角度的变化与对应骨骼应力分布情况。方法:选取1名女性中度拇外翻志愿者,采集CT影像数据,利用计算机三维成像技术进行三维有限元建模,验证模型有效性,标准化第1跖趾关节角与第1-2跖间夹角的测量方法,控制变量,依次改变作用力大小来观察上述两角度的变化,分析第1跖骨、近节趾骨的应力分布情况。结果与结论:(1)建立了有效的中度拇外翻足有限元模型,并显示较大的应力集中现象出现在第1跖骨,分布趋势为由骨体内侧中部及外侧中部,逐渐向骨体背侧底侧减小;(2)验证了所采用的第1跖骨、第2跖骨和拇趾近节趾骨轴线参考点的确定方法在有限元分析中的可实施性;(3)作用在第1拇趾远节趾骨外侧中部区域水平力对第1跖趾关节角的改变有直接影响,但并非线性影响;作用于足跖趾关节内侧囊处区域力主要影响第1-2跖骨间角大小;作用在跖骨近端内侧面水平力对两角度的影响都不大。

BACKGROUND: Finite element model construction and biomechanical analysis make it possible to explore the formation of hallux valgus and the recovery of related structures and functions. OBJECTIVE: To establish a finite element model of moderate hallux valgus foot in the neutral position with load to analyze the changes of the angle of the first metatarsophalangeal joint and the stress distribution of the corresponding bones under the action of external forces of different parts and sizes.METHODS: One female volunteer with moderate hallux valgus was selected, and CT image data were collected. The computer 3D imaging technology was used to conduct 3D finite element modeling to verify the validity of the model, and standardize the measurement method of the angle of the first metatarsophalangeal joint and the angle between the first and second metatarsal. Variables were controlled and the force was changed in turn to observe the changes of the above two angles, and analyze the stress distribution of the first metatarsal and proximal phalanx.RESULTS AND CONCLUSION:(1) An effective finite element model of moderate hallux valgus foot was established, which showed that a large stress concentration appeared in the first metatarsal. The distribution trend was from the medial middle and lateral middle of the bone body, gradually decreasing towards the dorsal and basal sides of the bone.(2) The feasibility of the method for determining the axis reference point of the first metatarsal, the second metatarsal and the proximal phalanx of the great toe was verified in finite element analysis.(3) The horizontal force acting on the lateral middle area of the distal phalanx of the first great toe has a direct effect on the change of the first metatarsophalangeal angle, but it has no linear effect. The regional force acting on the medial capsule of the metatarsophalangeal joint mainly affects the size of the first-second metatarsophalangeal angle. The horizontal force acting on the medial surface of the proximal metatarsal has little effect on the two angles.