Weber-B型踝关节骨折修复下胫腓前韧带的生物力学研究

Biomechanical Study on Reconstructing the Anterior Tibiofibular Ligament for the Weber Type B Lateral Malleoar Fracture

目的评价踝关节骨折修复下胫腓前韧带的生物力学稳定性。方法采集国人新鲜足标本一具,截取踝关节以上15cm下肢小腿横行截断,暴露下胫腓前韧带。载荷实现分级加载,选用小腿极限载荷(踝关节负重力为4.5BW)20%作为生理载荷,即以0、100、200、300、400、500N为分级载荷。万能材料试验机(WD-5)的加载速率为1.40 mm/min,以准静态方式加载,载荷施加于下肢胫腓骨上。并模拟足运动中立位、跖屈位(30°)、背屈位(20°)、旋后外旋位等四种生理运动状况,正常足及切除下胫腓前韧带测定踝关节的应力变化、距骨的移位变化及轴向刚度数据。结果标本在正常足及切断下胫腓前韧带的不同功能位上,踝关节的应力变化、距骨的移位变化及轴向刚度,统计学有显著性差异(P<0.05)。结论在对内、外踝满意固定后,下胫腓前韧带的修复能更好恢复踝关节的生物弹性,最大限度恢复其原来的结构和功能,避免晚期创伤性关节炎的发生。

Objective To evaluate the biomechanical stability of restoration of anterior lower tibiofibular ligament in ankle fracture. Methods Collect a fresh foot sample of Chinese,cut off transversely of the shank 15 em above the ankle joint ,operate carefully around the ankle joint as per the clinic procedures ,to expose the anterior lower tibiofibular ligament,calcaneofibular ligament,anterior and posterior talofibular ligament for the test. The entire structural simulation is based on the fresh foot sample of normal human corpse and in the phased loading,with 20% of the shank limit load （the bearing capacity of ankle joint at 4.5 BW） as the physiological load ,i. e. the phased load of 0,100,200, 300,400 and 500N. The loading rate of the universal material tester （WD 5） is 1.40 mm/min,and with the quasistatic loading mode. The load is applied on tibiofibular bone of the shank to simulate the 4 physiological movement status of the foot,i, e. neutral position,metastarsal bending position（30°） ,posterior bending position（20°） and esternally rotated position. The normal foot and amputation of anterior lower tibiofibular ligament was used to test the stress change of ankle joint,displacement and axial rigidity of astragalus. Results The sample is placed in the different functional positions of the normal foot and when cutting off anterior lower tibiofibular ligament,it is significantly different in the stress change of ankle joint,displacement and axial rigidity of astragalus and in 2 status（normal foot and cutting off anterior lower tibiofibular ligament） （P〈0.05）. Conclusion Upon the satisfactory fixation of the interior and exterior ankle,restoration of anterior lower tibiofibular ligament can better restore the biological flexibility of the ankle joint ,maximally recover its original structure and function and avoid the occurrence of late traumatic arthritis.