股骨动力加压凹槽交锁髓内钉对稳定骨折治疗作用的生物力学研究

Biomechanical study of a new grooved interlocking dynamic compressing intramedullary nail for femoral fracture

目的研制新型股骨髓内钉并对其生物力学性能进行测评,探讨其在稳定骨折治疗中动力加压机制的表达与力学性能的优劣。方法将新型股骨髓内钉与Orthofix进口交锁髓内钉及AO加压钢板等不同方式内固定在稳定骨折条件下的抗轴向压缩、抗侧弯、抗旋转力学性能进行测试与比较。结果稳定骨折情况下,新型髓内钉对轴向压缩载荷的反应表现为断端间的动力加压作用,其应力遮挡效应明显低于髓内钉及钢板对照组;三点弯曲试验中,各组试样均表现出抗内→外弯曲能力较抗前→后弯曲能力强的特点,新型髓内钉的抗侧弯性能优于髓内钉对照组,钢板对照组抗侧弯性能最佳;钢板内固定的抗旋转能力均优于髓内钉内固定,新型髓内钉抗旋转性能优于髓内钉对照组。结论新型髓内钉设计合理,力学性能优良,动力加压功能明显,应力遮挡效应低,固定稳定性好;髓内钉与髓腔匹配情况及骨髓腔形态亦是影响旋转及侧弯稳定性的重要因素。

Objective To develop a new femoral intramedullary nail and evaluate its biomechanical property, and study its dynamic compressing mechanism and mechanical characteristics in steady femoral fracture. Methods The anti-axile compression, anti-lateral bending and anti-torsion properties of the new grooved interlocking dynamic compressing intramedullary nail （GIMN） were tested and compared with those of general imported interlocking intramedullary nail and dynamic compression plate in treating steady femoral fracture, Results Applied in steady femoral fracture, the new femoral intramedullary nail manifested a dynamic compressing effect when exerted to an axile compression and its stress shielding effect was significantly smaller than that of general interlocking intramedullary nail and dynamic compression plate （P〈0.05）. In bending test, the anti-lateral bending rigidity was stronger than anti-anteroposterior bending rigidity in all three groups, while the GIMN was more effective in antilateral bending than general interlocking intramedullary nail; dynamic compression plate was more effective than intramedullary nail in anti-torsion property, while the GIMN was more effective than general interlocking intramedullary nail. Conclusion The new grooved interlocking dynamic compressing intramedullary nail is designed scientifically, with a reliable fixation, favorable dynamic-compressing effect and few stress shelter effects; the matching of intramedullary nail and medullary cavity as well as the shape of medullary cavity is important for anti-torsion and anti-lateral bending stability.