股骨型髓内分叉钉的生物力学研究与临床应用

The Biomechanical Evaluation of Intramedullary Tridentate Nails for Femoral Shaft Fractures

目的 研究新型股骨型髓内分叉钉治疗股骨下段骨折的生物力学特性。方法 将 36根成人股骨尸骨标本随机分为三组 ,并在股骨的下 1/ 4处锯断 ,做成股骨中下段横型骨折的模型 ;分别用股骨型髓内分叉钉、Ender钉和梅花钉固定 ;然后各组分别进行抗扭、抗弯和抗拉生物力学实验。结果 股骨型髓内分叉钉的抗扭、抗弯和抗拉性能明显优于Ender钉和梅花钉。髓内分叉钉的扭强度是Ender钉和梅花钉的 2 8倍和 4 4倍 ,抗扭刚度系数α也明显高于Ender钉和梅花钉 (P <0 0 1) ;抗弯强度是Ender钉和梅花钉的 2 3倍和 1 4倍 ,抗弯刚度系数 β也明显高于Ender钉和梅花钉 (P <0 0 1) ;髓内分叉钉的抗拉强度随位移的增加而逐渐增大 ;当位移达到 5mm时 ,抗拉强度是Ender钉和梅花钉的 1 7倍和 4 5倍。结论 髓内分叉钉的设计符合股骨下段解剖特点 ,具有良好的生物力学性能 。

Objective To investigate the biomechanical characteristics of intramedullary tridentate nails(ITN) in the distal femoral shaft fractures.Methods Thirty-six specimens of adult femur were randomly divided into three groups and were osteotomized transversely in the distal fourth of the femur.ITNs,Ender nails and Cloverleaf nails were implanted into each group of femurs respectively.Torsional,bending and axial tensile tests were performed in each group of specimens.Results The characteristics in resistance to torsion,bending and stretch of ITNs were much better than that of Ender nails and Cloverleaf nails.The torsional strength of ITNs was 2 8 times than that of Ender nails and 4 4 times than that of Cloverleaf nails.The coefficient of torsional stiffness(α) of ITNs was significantly greater than Ender nails and cloverleaf nails(P<0.01).The bending strength of ITNs was 1 4 times than that of cloverleaf nails and 2 3 times than that of Ender nails.The coefficient of bending stiffness(β) of ITNs was significantly greater than Ender nails and cloverleaf nails(P<0.01).The tensile strength of ITNs got greater along with the displacement increase.While the displacement was 5 mm,the tensile strength of ITNs was 1 7 times than that of Ender nails and 4 5 times than that of Cloverleaf nails.Conclusion The design of ITN accords with the special anatomical structure of the distal femur.The biomechanical characteristics of ITNs are very well.Therefore,ITN is a new kind of intramedullary nails.