RESUMO
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.