锚钉数量及位置对肩关节Bankart损伤修复强度影响的有限元分析

Finite element analysis of the influence of anchorage number and location on Bankart repair strength of shoulder joint

目的:通过有限元分析的方法,研究不同锚钉数量及位置对肩关节Bankart损伤修复强度影响。方法:利用逆向建模技术,将包含正常成人志愿者肩关节的三维CT数据,导入Mimics 10.0、Geomagic 2012软件中对相关组织进行重建,然后在Hypermesh 13.0软件中进行网格划分,赋予材料属性,在Abaqus 6.14中调整MPC约束的位置及数量,建立A模型(正常对照模型)、B模型(Bankart损伤对照模型)、C模型(1枚锚钉)、D模型(2枚锚钉)、E模型(3枚锚钉)、F模型(4枚锚钉),6种工况的肩关节有限元模型。添加肱骨外旋及前移载荷,模拟肩关节前向不稳的恐惧试验。结果:(1)正常情况下,伴随着肱骨头的外旋下盂肱韧带复合体出现皱褶,并且在其前后束止点周围出现明显的应力集中。(2)Bankart损伤导致下盂肱韧带前束应力增大52.33%、后束增大45.67%,游离部分关节盂唇出现不均匀剪应力降低。(3)锚钉修复的各模型中,锚钉部位均出现明显的应力集中,并能够减小前后束韧带的应力,其中C、D模型与B模型比较差异无统计学意义(P>0.05),E、F模型与B模型比较差异有统计学意义(P<0.05)。结论:在修复Bankart损伤时,应用1枚或2枚锚钉能够减小下盂肱韧带前后束的应力,但如外旋角度较大时,在锚钉位置产生的应力集中明显增大,增加修复失败的风险。而应用3枚或4枚锚钉,能够通过锚钉之间的"负荷共享"效应增强对下盂肱韧带约束,并且减少锚钉自身的应力,从而确保肩关节的前方稳定,为患者的早期康复提供力学环境。

Objective:To study the influence of the number and position of anchor nails on the Bankart repair by the finite element analysis. Methods:The 3D CT data of shoulder joints including normal adult volunteers were imported into Mimics10.0 and Geomagic 2012 software to reconstruct the related tissues,and then meshed in Hypermesh 13.0 software to give material attributes. The position and number of MPC constraints were adjusted in Abaqus 6.14 to establish finite element model of shoulder joint under 6 working conditions including A model(normal control model),B model(Bankart damage control model),C model(1 anchor),D model(2 anchors),E model(3 anchors),F model(4 anchors). The humerus external rotation and forward load were added to simulate the fear test of the shoulder joint forward instability. Results:(1)Normally,the inferior glenohumeral ligament complex accompanied by the external rotation of the humerus head has a wrinkle and a significant stress concentration around its anterior and posterior bundle terminations.(2)The stress of the anterior bundle and posterior bundle of the inferior glenohumeral ligament were increased by 52.33% and 45.67% respectively after Bankart’s injury.(3)In each model of anchor repair,the stress concentration was obvious at the anchor site,and the stress of anterior and posterior bundle ligaments could be reduced; there were no obvious differences between C,D models and B model(P>0.05),and there were significant differences between E,F models and B model(P<0.05). Conclusion:One or two anchors can reduce the stress of the anterior and posterior bundles of the inferior glenohumeral ligament in the repair of Bankart’s injury,but when the angle of rotation is large,the stress concentration in the anchor position increases significantly,leading to the increases of the risk of failure.The application of three or four anchors can enhance the constraints on the inferior glenohumeral ligament and reduce the stress of the anchor itself through the "load sharing"effect between anchors,so as to ensure the stability of the shoulder joint and provide a mechanical environment for the early rehabilitation of patients.