儿童肱骨远端骨干干骺端交界区骨折不同固定方法生物力学的比较

A biomechanical comparison on different fixation techniques in metaphysealdiaphyseal junction fractures of distal humerus in children

目的比较儿童肱骨远端骨干干骺端交界区骨折不同固定方法的生物力学稳定性。方法采用复合人工骨36根,模拟制作高、中、低位骨干-干骺端交界区横行骨折线,对不同骨折模型分别行克氏针、单臂外固定架和弹性髓内钉固定,并将模型骨安装在计算机控制万能试验机上进行屈曲、伸直、外翻、内翻应力试验,将模型安装在机电扭力试验机上,进行内旋转、外旋转应力试验,比较不同固定方法力学稳定性。结果高位骨折模型采用弹性髓内针固定力学稳定性最佳,中位骨折采用3枚交叉克氏针(1枚内侧克氏针和2枚外侧克氏针)固定力学稳定性最佳,低位骨折采用枚交叉克氏针(1枚内侧克氏针和2枚外侧克氏针)固定力学稳定性最佳。结论弹性髓内钉固定对儿童肱骨远端骨干干骺端交界区上半区(高、中位骨折线区间)骨折的整体稳定性最好,而克氏针固定在稳定下半区(中、低位骨折线区间)骨折方面稳定性最好。2枚外侧针固定、1枚内侧针固定可以获得最佳的力学稳定性。

Objective To compare biomechanical stability of different fixation techniques in metaphyseal-diaphyseal junction fractures of the distal humerus in children.Methods Thirty-six composite artificial bones were used to simulate the transverse fracture line of the high,middle and low diaphysis-metaphysis junction.The fractures were respectively fixed with Kirschner wires(K-wires),lateral external fixation(LEF)and elastic stable intramedullary nails(ESIN).Model bones were then attached to a microcomputer controlled universal stress testing machine and tested in extension,flexion,valgus and varus,and then to an electromechanical torsion testing machine and tested in internal and external rotations,to compare biomechanics stability of different fixation techniques.Results For the high fractures,elastic stable intramedullary nails yielded the best stiffness in all directions.For the middle fractures,3 crossed pinning(1-medial and 2-lateral)had the best overall stiffness.For the low fractures,3 crossed pinning(1-medial and 2-lateral)still had the best stiffness.Conclusion Elastic stable intramedullary nails yield the best overall stiffness for the metaphyseal-diaphyseal junction fractures in the upper region(the region between high and middle fracture line)of the metaphyseal-diaphyseal junction,while that percutaneous pinning is superior in stabilizing fractures of the lower region(the region between middle and low fracture line).Two lateral and one medial pins make the most stable construct.