旋转臂自锁式髓内钉固定股骨干骨折的生物力学研究

The Biomechanical Study of Rotating-arm Self-locking Intramedullary Nails in Comminuted Femoral Shaft Fractures

将14根成人股骨标本分成两组,制成股骨中段粉碎性骨折模型,将自研的旋转臂自锁式髓内钉作为实验组和国产带锁髓内钉作为对照组,分别对骨折模型进行固定,在M TS试验机上对髓内钉及髓内钉固定骨折模型依次进行旋转、四点弯曲及压缩试验,比较旋转臂自锁式髓内钉与国产交锁髓内钉的力学性能。为旋转臂自锁式髓内钉设计的改进、临床应用及推广提供理论依据。结果显示:(1)实验组钉骨试件的抗扭转钢度为0.89 Nm/度,对照组钉骨试件的抗扭转刚度为1.18 Nm/度,实验组钉骨试件的抗扭转刚度小于对照组,为对照组的75.4%;实验组钉骨试件在扭角为16°时的扭矩为14.44 Nm,对照组钉骨试件为22.44 Nm,实验组钉骨试件的扭矩小于对照组,约为对照组的64.3%。(2)试验组钉骨试件的抗弯刚度为1 535 N cm/mm,对照组钉骨试件的抗弯刚度为1 737N cm/mm,对照组大于试验组,但无统计学意义(P>0.05)。(3)实验组最大轴向载荷为1 339 N,试件变形为3.5mm;对照组为1 910 N,试件变形为5.2 mm。对照组的最大载荷大于实验组(P<0.05)。在2倍体重时,实验组的位移为2.1 mm,对照组为3.0 mm,实验组小于对照组(P<0.05),实验组的抗短缩刚度大于对照组。(4)实验组髓内钉的力学指标比对照组小,髓内钉的各项力学指标均大于髓内钉股骨试件。因此,旋转臂自锁式髓内钉能够满足固定股骨干粉碎性骨折的生物力学要求和临床内固定的需要。

This study was sought to compare and evaluate the blomechanical properities of rotating-arm selflocking intramedullary nails （RSIN） with domestic femoral intramedullary nail （DFIN） in communited femoral shaft fractures. A 2 cm midshaft defect was created on seven pairs of cadaver femur, and fixed with two kinds of intramedullary nails. Then the torsion, four-point bending and axial loading to failure were tested on these models. The load versus deformation curve was generated from the load recorded by the load cell and the deformation simultaneously recorded by the linear variable displacement transducer. The mean torsional stiffness of the femora fixed with RSIN was 0. 98 Nm/degree, which was significantly less than that fixed with the similar nails reported in documents, and the mean value of bending stiffness of the femur fixed with DFIN was larger than that of the femur fixed with RBIN, but there was no significant statistic difference. For use in fracture models under compression load beyond 1 200 N, the RBIN was more rigid than DFIN, which provided the biggest load. All the parameters of the test with nails were greater than that for femur fixed with nails. In conclusion, FBIN probably provides enough strength and rigidity for use in communited femoral shaft fractures.