低应力遮挡效应交锁髓内钉的研制与生物力学研究

目的 :研究新型股骨低应力遮挡交锁髓内钉治疗股骨干骨折的生物力学特性。方法 :将股骨干交锁髓内钉远端锁孔向近端分别扩大 1、 2、 3mm ,采用 4具成人男性尸体 8根股骨干标本制成横断骨折模型 ,分别打入 4种不同孔径髓内钉 ,进行骨折断端应力分析实验。结果 :远端锁孔直径 3mm的交锁髓内钉与实验中其它组相比较 ,应力遮挡率最小 ( 2 0 .6 0 %) (P <0 .0 5 ) ,在载荷—应变、载荷—位移、轴向强度及刚度上均占有明显优势 (P <0 .0 5 )。而 4种髓内钉在弯矩—应变、弯矩—桡度、扭矩—扭角关系中无明显差别。结论 :远端锁孔直径扩大 3mm的交锁髓内钉不但应力遮挡小 ,而且强度、刚度符合骨折内固定的生物力学要求 ,从而该实验为临床应用低应力遮挡交锁髓内钉提供了可靠理论依据。

Design and biomechanics of low stress-shielding interlocking nail

Objective: To research the biomechanical character of a new type low stress-shielding interlocking nail for treatment of femoral fracture.Method:Eight transverse fractures were made at 4 cadaveric femoral shafts and fixed with new designed low stress-shielding interlocking nail whose distal holes were enlarged to 1mm, 2mm and 3mm respectively.The model with the four type interlocking nails fixed was carried out stress analysis.Result:The interlocking nails whose diameter of distal screw hole 3mm larger than normal not only have the lowest rate of stress shielding (20.60%,P<0.05),but also have an advantage over the other interlocking nails of the experiment in load-strain,load-displacement and axial strength((P<0.05)). In the relationship of bending moment-strain,bending moment-bending deflection and torque-torisional angle,they have no evident difference((P>0.05)).Conclusion:The interlocking nail whose distal screw hole 3mm larger than normal one not only have the lowest stress-shielding,but also cater for the biomechanical demands of fracture fixation.Thereby,the experiment provides dependable basis for the applying of low stress-shielding interlocking nail.