空心螺钉不同固定方式治疗后踝骨折的生物力学研究

目的 基于有限元方法研究空心螺钉不同角度固定对后踝骨折的生物力学影响，确定空心螺钉的最佳固定方式。方法 采用CT图像重建包含胫骨、腓骨、距骨以及相应软骨和韧带的踝关节有限元模型，在验证其有效性基础上建立1/2后踝骨折模型，分析空心螺钉不同固定方式对后踝骨折固定模型的生物力学影响。结果 与螺钉0°、5°、10°、20°固定相比，螺钉15°固定时模型位移最小。螺钉15°固定时，螺钉应力比螺钉5°、10°、20°固定模型小，比螺钉0°固定模型大。但螺钉0°固定时，踝关节接触应力峰值比正常踝关节接触应力峰值大得多，易造成创伤性骨关节炎。结论 空心螺钉治疗累及关节面不超过1/2的后踝骨折安全有效；螺钉以不同角度固定时，模型的位移和应力不同。螺钉固定角度为15°时生物力学稳定性最好，可用于指导临床手术。

Biomechanical Study on Different fixation Methods of Cannulated Screws for Posterior Malleolus Fracture

Objective To study biomechanical effects of cannulated screws at different fixation angles on posterior malleolus fracture based on finite element method, so as to determine the best fixation method of cannulatedscrew. Methods The finite element model of ankle joint, including tibia, fibula, astragalus, corresponding cartilage and ligaments was reconstructed using CT images, and 1 / 2 posterior malleolus fracture model was established on the basis of verifying its validity. The biomechanical effects of cannulated screw fixation on posterior malleolus fracture fixation model were analyzed. Results Compared with 0°,5°,10°,20° fixation model, the 15° fixation model had the smallest displacement. The screw stress of 15° fixation model was lower than that of 5°, 10°, 20° fixation model, and higher than that of 0° fixation model. But when the screw fixation angle was 0°, the peak contact pressure of ankle joint was much larger than that of normal ankle joint, which was easy to cause traumatic osteoarthritis. Conclusions Cannulated screw is safe and effective for treating posterior malleolus fracture which is less than 1 / 2 fragment size. The displacement and stress of the model are different at different fixation angles of screws. When the fixation angle of screw is 15°, the biomechanical stability is the best, which can be used to guide clinical operation.