改良型γ钉固定股骨转子下骨折的生物力学与临床应用

Improved Gamma Nail for the Subtrochanteric Fracture of the Femur: A Biomechanical and Clinical Study

目的：探讨改良型γ钉固定股骨转子下骨折的生物力学及临床疗效。方法：对原Ｇａｍｍａ钉的大小和结构进行改良并对改良后的γ钉作轴向压缩试验和三点弯曲试验。临床应用本钉治疗股骨转子下骨折２３例。结果：本钉的抗轴向压缩和抗弯曲强度两项指标均远超过人股骨（Ｐ＜０．０５）。本组２３例病人中，２２例获随访１～６年，骨折全部愈合。结论：本钉在股骨近段内的应力分布更合理，避免了因应力集中造成股骨干骨折的危险。其髓内棒位于股骨中位轴上，钉棒之间的力臂较短，产生的弯矩较小。髓内棒的上、下端有螺丝钉交锁，可防止骨折移位和棒的旋转、下沉，起静力性交锁固定作用。

We modified the Gamma nail mainly on size and structure and then tested the newly improved Gamma nail on axial compressive and threepoint bending test. 23 cases of the subtrocthanteric femoral fracture were treated by using the new devices. The results of biomechanical study showed that the axial compressive and bending strength of the new device were far stronger than that of the human femur(P<0.05). Of 23 cases, 22 were followed up from 1 to 6 years and all of the fractures were healed. The new nail was more reasonable in the distribution of stress in the proximal part of the femur. This was able to prevent the danger of femoral fracture due to stress concentration. Since its rod was placed in the neutral axis of the femur, its moment was less. Because there was a neck screw and a distal locking screw to be interlocked in the proximal and distal end of the rod, this device was able to prevent the displacements of fracture fragments, the rotation and descending of the intramedullary rod, and played the role of static interlocking fixation. It could be applied to various types of subtrochanteric fracture of the femur.