马蹄环式外固定架固定AO-C2型Pilon骨折在轴向载荷下的稳定性

目的 在传统环形外固定架构型基础上进行重新设计，使其更适合关节内Pilon骨折的固定。通过定量分析负重载荷下应用马蹄环形外固定架固定Pilon骨折端位移以验证该外固定架的稳定性。方法 采用摆锯依据预先制定的截骨线制备AO-C2型Pilon骨折模型，应用马蹄环形外固定架对其固定，然后于力学加载机上进行轴向载荷力学加载。轴向载荷加载方式为从0 N开始依次加载至150、300、450 N。用动态捕捉仪记录轴向载荷加载过程中骨折块在X（左右）、Y（上下）、Z（前后）轴的移位变化。结果 腓骨左右、上下、前后方向整体移位范围分别为0.32～0.70、-0.27～-0.23、0.23～0.32 mm，最大差值为0.09 mm。胫骨内踝侧骨折块左右、上下、前后方向整体移位分别为0.02～0.14、-0.80～-0.19、-0.78~-0.1 mm。胫骨外踝侧骨折块左右、上下、前后方向整体移位范围分别为-0.07~0.05、-0.36~-0.03、0.27～0.47 mm。结论 马蹄环形外固定架不仅能实现骨折端的稳定固定且能产生有利于骨折愈合的微动，符合骨折愈合的生物力学特点。该外固定架构型简单，适合Pilon骨折的治疗，值得推广应用

Stability of Fixation for AO-C2 Pilon Fracture with Horseshoe Ring External Fixator under Axial Loading

Objective The traditional circular external fixation structure was redesigned to make it more suitable for intraarticular Pilon fracture fixation. The stability of the horseshoe annular external fixator was verified by analyzing fracture displacement of the Pilon bone after fixation with the external fixator under loading.MethodsAO-C2 Pilon fracture model was prepared by pendulum saw according to predetermined osteotomy line, and then fixed by horseshoe ring external fixator. The fixed ankle model was subjected to axial loading on mechanical test machine. The axial force loading mode was from 0 N to 150 N, 300 N and 450 N successively. The displacement changes of fracture blocks in X (left-right), Y (up-down) and Z (anterior-posterior) axis during axial loading were recorded by dynamic capture instrument.ResultsThe overall left-right, up-down and anterior-posterior displacement of the fibula ranged from 0.32 mm to 0.70 mm, -0.27 mm to -0.23 mm and 0.23mm to 0.32 mm, and the maximum difference was 0.09 mm. The overall left-right, up-down and anterior-posterior displacement of medial malleolus fracture in the tibia range from 0.02 mm to 0.14 mm, -0.80 mm to -0.19 mm and -0.78 mm to -0.13mm.The overall left-right, up-down and anterior-posterior displacement of lateral malleolus fracture in the tibia ranged from -0.07 mm to 0.05 mm, -0.36 mm to -0.03 mm, 0.27 mm to 0.47 mm.ConclusionsThe horseshoe ring external fixator can not only stabilize the fracture end, but also produce micromotion which is beneficial to fracture healing, which accords with biomechanical characteristics of fracture healing. The external fixator structure is simple, suitable for the treatment of Pilon fracture, and worthy of popularization and application.