踝外侧副韧带损伤对踝关节稳定性及软骨接触应变影响的有限元分析

Finite element analysis of the influence of lateral ankle collateral ligament injury on ankle joint stability and cartilage contact strain

背景:在踝关节扭伤和踝关节韧带损伤中近85%涉及外侧副韧带,损伤的机制为足跖屈时踝关节内翻。急性踝关节外侧扭伤的患者中有20%-40%会出现持续疼痛和慢性踝关节外侧不稳,导致距骨平移和旋转过大,加速软骨磨损,导致关节退化。目的:通过有限元建模探究不同类型的踝外侧副韧带损伤模型对踝关节稳定性以及距骨穹窿软骨接触应变的影响。方法:将1名27岁志愿者足踝CT扫描数据DICOM文件导入有限元软件中,进行三维重建及曲面拟合,再进行网格划分,建立含有骨骼、关节软骨和韧带的完整踝关节有限元模型,对比正常、距腓前韧带损伤、跟腓韧带损伤和距腓前韧带+跟腓韧带损伤4种不同工况下的踝关节稳定性和距骨软骨接触应变的改变。结果与结论:①在前抽屉试验中,距腓前韧带损伤和距腓前韧带+跟腓韧带损伤距骨前移距离明显大于正常和跟腓韧带损伤(P<0.05),而距腓前韧带损伤和距腓前韧带+跟腓韧带损伤之间、正常和跟腓韧带损伤之间差异无显著性意义(P>0.05);②在距骨倾斜试验中,跟腓韧带损伤和距腓前韧带+跟腓韧带损伤距骨倾斜角度明显大于正常和距腓前韧带损伤,而跟腓韧带损伤和距腓前韧带+跟腓韧带损伤之间、正常和距腓前韧带损伤之间无明显差异;③在单足站立试验中,与正常模型相比,上述3种损伤模型改变了距骨穹窿软骨接触应变分布,峰值由距骨穹窿前外侧转移至前内侧,导致了距骨穹窿软骨前内侧压力增高,并且峰值大小比较:距腓前韧带+跟腓韧带损伤>距腓前韧带损伤>跟腓韧带损伤>正常,距腓前韧带+跟腓韧带损伤的峰值明显大于距腓前韧带损伤和跟腓韧带损伤;④研究结果验证了踝外侧副韧带损伤时踝关节稳定性的丢失和前内侧软骨接触应变峰值增加,揭示了慢性踝关节外侧不稳和踝关节骨关节炎之间的联系,确认了修复或者重建距腓前韧带和跟腓韧带的必要性,为慢性踝关节外侧不稳的手术治疗提供了理论依据。

BACKGROUND:Of ankle sprains and ankle ligament injuries,nearly 85%involved the lateral collateral ligaments,and the mechanism of injury was ankle varus during plantar flexion.Between 20%and 40%of patients with acute lateral ankle sprains develop persistent pain and chronic lateral ankle instability,resulting in excessive translation and rotation of the talus,accelerated cartilage wear and joint degeneration.OBJECTIVE:To explore the effects of different types of lateral ankle collateral ligament injury models on ankle joint stability and contact strain of talus dome cartilage through finite element modeling.METHODS:The DICOM file of CT scan data of the ankle joint of a 27-year-old volunteer was imported into the finite element software for three-dimensional reconstruction and surface fitting,and then mesh division was carried out to establish a complete finite element model of the ankle joint containing bones,articular cartilage and ligaments.The changes of the ankle joint stability and talus cartilage contact strain were compared under four different conditions:normal,anterior talofibular ligament injury,calcaneofibular ligament injury and anterior talofibular ligament+calcaneofibular ligament injury.RESULTS AND CONCLUSION:(1)In the anterior drawer test,the anterior talar translation of anterior talofibular ligament injury and anterior talofibular ligament+calcaneofibular ligament injury was significantly greater than that of normal and calcaneofibular ligament injury(P<0.05),but there was no significant difference between anterior talofibular ligament injury and anterior talofibular ligament+calcaneofibular ligament injury and between normal and calcaneofibular ligament injury(P>0.05).(2)In the talus tilt test,the talus tilt angle of calcaneofibular ligament injury and anterior talofibular ligament+calcaneofibular ligament injury was significantly larger than that of normal and anterior talofibular ligament injury,but there was no significant difference between calcaneofibular ligament injury and anterior talofibular ligament+calcaneofibular ligament injury,and between normal and anterior talofibular ligament injury.(3)In the unipedal standing test,compared with the normal model,the above three injury models changed the contact strain distribution of talus dome cartilage and shifted the peak value from the anterolateral side to the anteromedial side of the talus dome,resulting in the increase of anteromedial pressure of talus dome cartilage,and the comparison of the peak values was:anterior talofibular ligament+calcaneofibular ligament injury>anterior talofibular ligament injury>calcaneofibular ligament injury>normal,and the peak value of anterior talofibular ligament+calcaneofibular ligament injury was significantly higher than that of anterior talofibular ligament injury and calcaneofibular ligament injury.(4)The results confirmed that the injury of the lateral collateral ligament of the ankle would lead to the loss of ankle stability and the increase of peak contact strain of anterior medial cartilage,revealed the relationship between chronic lateral ankle instability and ankle osteoarthritis,and concluded the necessity of repairing or reconstructing anterior talofibular ligament and calcaneofibular ligament,which provided a theoretical basis for surgical treatment of chronic lateral ankle instability.