交锁髓内钉断钉与骨不连的力学研究及临床意义

The Biomechanic Principle and Its Clinical Significance of Nail Broken and Nonunion with Locked Intramedullary Nailing

目的:分析交锁髓内钉断钉和骨不连的力学机理,探讨其临床意义和预防方法。方法:将静力外带锁髓内钉远端的圆形锁孔改为长形锁孔,近端改为尾翼状,在粉碎、横断、斜型骨折模型上测量髓钉与锁钉间的剪力和骨折断端间的压力并与静力固定比较。临床随访、分析86例股骨和胫骨骨折静力交锁钉固定的相关并发症。结果:静力固定必然产生髓钉与锁钉间的剪力,其大小约等于正压力;改良交锁钉消除了髓钉与锁钉间剪力对骨折端的应力遮挡;86例中,骨延迟愈合、骨不愈合和断钉分别为7例(8.14％)、3例(3.49％)、2例(2.34％)。结论:骨不连是应力遮挡和血供障碍的必然结果;钉-钉间剪力、骨不连又是造成断钉的重要原因。预防方法是使用动力交锁内固定。

Objective: To analyze the biomechanic principle of nail broken and non-union in locked intramedullary nailing and discuss its clinical significance and prevention. Method .-The round hole of locked intramedullary nailing was changed to long pore and its proximal to tail wing shape with self-locking. The shears force between intramedullary nail and locked nail, the pressure between the fragments was measured and compared with static fixation. Eighty-six cases fracture of femur and tibia fixed with locked intramedullary nailing were followed up. Result: Improved nail can eliminated the stress shielding between the fragments . Delayed union, nonunion and nail broken are 7(8.14%),3(3.49%) and 2 (2.34 %) in 86 cases. Conclusion: Nonunion is a result of stress shielding and blood deficiency,but they are the important causes of nail broken. The preventive method is using dynamic fixation.