Blum J, Machemer H, Baumgart F, Schlegel U, Wahl D, Rommens P M
Department for Trauma Surgery, University Clinics Mainz, Germany.
J Orthop Trauma. 1999 Jun-Jul;13(5):344-50. doi: 10.1097/00005131-199906000-00004.
To establish whether the bending and torsional stiffness of an implanted nail are influenced by nail design and nail-bolt interface, this study compared two implanted retrograde nail systems: the AO/ASIF unreamed humeral nail (UHN) and the Russell-Taylor (RT) nail.
Pair randomization.
Mechanical laboratory testing.
Twelve pairs of freshly harvested cadaveric humeri.
Transverse fractures were simulated with a standardized midshaft osteotomy and a three-millimeter gap. Both nails were proximally and distally interlocked. The RT nail has a single interlock at its base and tip. The UHN has double interlocking both proximally and distally. The screw hole design of the RT nail features slots, whereas the UHN has round screw holes.
Anteroposterior and mediolateral bending stiffness and torsional stiffness.
The RT nail showed higher bending stiffness in anteroposterior and mediolateral bending. Large differences were seen in the torsional characteristics: for the first 30 degrees, the RT nail showed a much lower resistance against torsion than the UHN. Analysis of variance of stiffness at four, six, and eight newton-meters showed statistical significance (p < 0.0001). Torsional stiffness, defined as the slope of a straight line approximated to between 75 and 100 percent of the maximum torque, was very similar in both nails.
The torsional differences between the two nail systems are attributable to the nail-bolt interface of the RT nail. This dynamic system allows a clinically relevant degree of movement. The greater resistance to rotatory forces of the UHN is explained by the fact that the interlocking at its tip and base creates a static rather than a dynamic system.
为确定植入钉的弯曲和扭转刚度是否受钉的设计及钉 - 螺栓界面的影响，本研究比较了两种植入式逆行钉系统：AO/ASIF非扩髓肱骨钉（UHN）和罗素 - 泰勒（RT）钉。
配对随机化。
机械实验室测试。
十二对新鲜采集的尸体肱骨。
采用标准化的肱骨干中段截骨术和三毫米间隙模拟横行骨折。两种钉均在近端和远端进行锁定。RT钉在其基部和尖端有单个锁定结构。UHN在近端和远端均有双重锁定。RT钉的螺孔设计有槽口，而UHN有圆形螺孔。
前后向和内外侧弯曲刚度以及扭转刚度。
RT钉在前后向和内外侧弯曲方面显示出更高的弯曲刚度。在扭转特性方面存在很大差异：在前30度，RT钉对扭转的抵抗力远低于UHN。在4、6和8牛顿 - 米时刚度的方差分析显示具有统计学意义（p < 0.0001）。扭转刚度定义为接近最大扭矩75％至100％之间的直线斜率，两种钉非常相似。
两种钉系统之间的扭转差异归因于RT钉的钉 - 螺栓界面。这种动态系统允许临床上相关程度的运动。UHN对旋转力的更大抵抗力可以解释为其尖端和基部的锁定形成了一个静态而非动态系统。
