Schopfer A, Hearn T C, Malisano L, Powell J N, Kellam J F
Orthopaedic Biomechanics Research Laboratory, Sunnybrook Health Science Center, Toronto, Ontario, Canada.
J Orthop Trauma. 1994 Oct;8(5):414-21. doi: 10.1097/00005131-199410000-00008.
Control of rotation after intramedullary fixation of the humeral shaft has been observed to vary clinically. Two of the newer intramedullary nails specifically designed for the humerus were tested. Transverse and spiral fractures were created in 35 fresh-frozen cadaveric humeri. The constructs were tested in a materials testing system to evaluate in vitro the torsional strength of the nailed humeral fractures. Intact bones showed a mean peak torque of 53 +/- 17 Nm. The humeri fixed with the Russell-Taylor nail (n = 18) using one interlocking screw proximally and one distally showed a mean torsional strength of 10.4 +/- 3.6 Nm. The specimens fixed with the Seidel nail (n = 17), interlocked proximally with two screws and distally by the friction of three expanded flanges against the inner cortex, had a significantly lower mean torsional strength of 1.5 +/- 0.6 Nm (p < 0.0005). When compared with intact bones, constructs using the Russell-Taylor nail achieved 20% of mean peak torque. This improved rotational strength should permit an earlier return to full functional use of the extremity.
肱骨骨干髓内固定后旋转控制的临床差异已被观察到。对两种专门为肱骨设计的新型髓内钉进行了测试。在35根新鲜冷冻的尸体肱骨上制造了横行和螺旋骨折。在材料测试系统中对这些结构进行测试，以体外评估带钉肱骨骨折的抗扭强度。完整的骨骼平均峰值扭矩为53±17 Nm。使用近端一枚交锁螺钉和远端一枚交锁螺钉的Russell-Taylor钉固定的18根肱骨，平均抗扭强度为10.4±3.6 Nm。用Seidel钉固定的17个标本，近端用两枚螺钉交锁，远端通过三个扩张凸缘与内皮质的摩擦力交锁，其平均抗扭强度显著较低，为1.5±0.6 Nm（p<0.0005）。与完整骨骼相比，使用Russell-Taylor钉的结构达到了平均峰值扭矩的20%。这种旋转强度的提高应能使肢体更早地恢复到完全功能使用状态。
