新型套筒式外固定器的生物力学相关研究

目的评价一种新型套筒式外固定器的生物力学性能以及不同骨断端间距(g)和骨-外固定杆间距(b-r)对骨-外固定器复合体稳定性的影响。方法采用7具新鲜成人尸体胫骨标本,制作骨折模型。使用新型套筒式外固定器固定骨折模型,根据骨折断端间距(0、1mm),骨-外固定杆间距(10、25、40、55mm)的不同组合,将实验共分为9组(包括无骨折对照组)。应用MTS实验机(美国产)对每一标本进行轴向压、扭转、前/后、内/外侧弯等四种负荷下的力学测试。计算其刚度值,以此反映不同情况下外固定器的稳定性。对骨断端间距(g)与固定器与骨间距(b-r)进行2×4的析因分析。结果骨断端间距(g)的差异对抗压、抗前后弯、抗侧弯三种刚度均有显著性意义(P均为0);骨与外固定杆间距(b-r)的差异对上述三种刚度也均有显著性意义(P<0.05);但对于抗扭转刚度均无显著性意义(P>0.05);对于四种刚度来说,两处理因素间均无交互效应(P>0.05)。结论骨断端间距(g)和骨-杆间距(b-r)对骨-外固定器复合体稳定性有不同程度的影响,新型套筒式外固定器具有良好的稳定性。

A biomechanical study on a new sleeve-style external fixation

Objective To evaluate the biomechanical performance of a new sleeve-style external fixation and investigate whether alteration of the bone gap and/or bone-rod distance can affect the stability of the bone-fixation combination. Methods 7 fresh human tibial specimens were made into fracture models, each of which was tested in 9 groups (including the intact as a control) of different bone gaps (0mm or 1mm) and the bone-rod distances (10mm, 25mm, 40mm, 55mm). During this experiment, nondestructive tests including axial compression, torsion, anterior-posterior bending and medial-lateral bending, were performed with multifunctional test system. The rigidity of each bone-fixation combination was calculated and noted as a sign of the stability. Student-T test was used in statistical analysis. Results The differences in the bone gap (0mm or 1mm) led to a significant change in the rigidity of axial compression, A-P bending and M-L bending (P< 0.05), but not in the rigidity of torsion. There was no interaction between 2 factors as far as the 4 kinds of rigidity were concerned. Conclusions The bone gap and the bone-rod distance can affect the stability of the bone-external fixation combination to different extents. The stability of the new sleeve-style external fixation can meet the biomechanical needs.