外固定器背伸位固定治疗三踝骨折外踝顶针生物力学研究

Biomechanical research on the pins of lateral malleolus when trimalleolar fracture is treated by external fixators fixed in dorsiflexion position

目的:探讨外固定器背伸位固定治疗三踝骨折时使外踝骨折稳定的踝关节固定位置。方法:应用手术截骨方法制作三踝骨折的尸体标本模型。复位后安装外固定器,并应用6根顶针复位与固定。于外踝顶针下表面贴应变片,并与应变仪导线连接。通过调整踝关节固定复位器,分别使踝关节固定于背伸中立、背伸内翻、背伸外翻3种位置。用试验机控制加载,应用应变仪采集顶针应变数据。结果:将踝关节分别固定于背伸中立位、背伸内翻位、背伸外翻位时,外踝外后侧顶针与外侧顶针随加载出现的应变值均较小;但3种位置相比,背伸中立位固定时外踝骨折的稳定性稍好。结论:应用外固定器治疗三踝骨折时,使外踝骨折稳定的最佳踝关节固定位置可能是背伸中立位。

Objective ： To explore the position of ankle joint in which fracture of lateral malleolus is stable when trimalleolar fracture is treated by external fixators fixed in dorsiflexion position. Methods：Corpse specimen model with trimalleolar fracture was made through the method of surgical osteotomy. External fixator was installed after the fracture was restored, meanwhile 6 pins was used. Straining flake was stuck on the lower surface of the pins of lateral malleolus ,and it was connected to strain gauge wires. Through adjusting the fixator of ankle joint, the ankle joint was fixed in dorsiflexion-neutral （ D-N ） position, dorsiflexion-varus （D-V） position and dorsiflexion-ecstrophy （D-E） position respectively. Load was controlled by testing machine, while the strain data of pins were collected through strain gauge. Results ： When ankle joint was fixed in D-N, D-V and D-E position respectively, the strain of both lateral posterior pin and lateral pin of lateral malleolus were small. The lateral malleolus fracture was more stable in D-N position than in another two positions. Conclusion ： When trimalleolar fracture is treated by external fixators, the best fixed position of ankle joint is dorsiflexion-neutral position on purpose of making lateral mal- leolus stable.