Kinast C, Frigg R, Perren S M
Orthopädische Klinik und Poliklinik, Technischen Universität München, Federal Republic of Germany.
Arch Orthop Trauma Surg. 1990;109(4):197-204. doi: 10.1007/BF00453141.
Conventional interlocking nails for the femur use an inclined proximal interlocking screw; the AO/ASIF universal interlocking nail utilizes a transverse interlocking screw which is anchored in cortical bone. The transverse position of the screw allows one to employ the nail for either the right or left side. The yield strength of the thinner diameter transverse screw, (thread 4.5 mm. core 3.0 mm) was compared with that of the Grosse-Kempf nail oblique screw (thread 6.3 mm, core 4.5 mm) by testing in cadaver femora to evaluate the risk of fatigue failure. The test, performed using slow loading rates (50 N/s), simulated either a diaphyseal or a subtrochanteric fracture situation. The test rig applied a load corresponding to body weight and pull at the trochanter. Taking the highest load without plastic deformation as a criterion, the mechanical strength of the two screws was evaluated for each fracture situation. The thinner but shorter transverse interlocking screw demonstrated higher strength (4500 N vs. 3000 N; P less than or equal to 0.02) than the thicker inclined screw in the diaphyseal and the subtrochanteric fracture situation (2300 N vs. 1100 N; P less than or equal to 0.06). The biomechanical test showed the transverse screw to have sufficient and superior strength.
传统的股骨交锁髓内钉使用倾斜的近端交锁螺钉；AO/ASIF通用交锁髓内钉采用横向交锁螺钉，该螺钉锚固于皮质骨。螺钉的横向位置使得该髓内钉可用于右侧或左侧。通过在尸体股骨上进行测试，比较了较细直径横向螺钉（螺纹4.5mm，髓心3.0mm）与Grosse-Kempf髓内钉倾斜螺钉（螺纹6.3mm，髓心4.5mm）的屈服强度，以评估疲劳失效风险。测试采用缓慢加载速率（50N/s）进行，模拟骨干或转子下骨折情况。测试装置施加相当于体重的载荷并在转子处施加拉力。以无塑性变形的最高载荷为标准，针对每种骨折情况评估两种螺钉的机械强度。在骨干和转子下骨折情况下，较细但较短的横向交锁螺钉显示出比较粗的倾斜螺钉更高的强度（4500N对3000N；P≤0.02）（2300N对1100N；P≤0.06）。生物力学测试表明横向螺钉具有足够且优越的强度。
