Department of Orthopaedics and Traumatology, University Medical Center Mainz, Johannes Gutenberg-University, Mainz, Germany.
AO Research Institute Davos, Davos, Switzerland.
J Bone Joint Surg Am. 2018 Jun 20;100(12):e83. doi: 10.2106/JBJS.17.00272.
Displaced transverse patellar fractures require open reduction and internal fixation. State-of-the-art stabilization techniques are tension band wiring (TBW) using Kirschner wires or cannulated screws. These techniques are associated with high rates of secondary fracture displacement, implant migration, implant prominence, wound-healing disturbances, and the need for implant removal. Recently, a locked intraosseous patellar nail prototype was developed. The aim of the present study was to investigate the biomechanical performance of this nail compared with TBW using cannulated screws.
Seven paired fresh-frozen human cadaveric knees were stripped of all soft tissues except the extensor apparatus. A transverse osteotomy was created to simulate an OTA/AO type 34-C1 transverse patellar fracture. The specimen pairs were randomly assigned to be fixed with TBW using cannulated screws or with the new intraosseous nail. Each specimen was cyclically tested for 5,000 cycles by pulling on the quadriceps tendon and simulating active knee extension and passive knee flexion within the range from 90° of flexion to full knee extension. Anterior and articular margin displacement of the fracture as well as interfragmentary rotation around the mediolateral axis were investigated with optical motion tracking after 100, 500, 1,000, 2,500, and 5,000 test cycles.
Within the respective 5 testing-cycle time points evaluated, the articular margin displaced on average 68%, 60%, 72%, 76%, and 81% less after intraosseous nailing compared with TBW. Whereas the difference remained nonsignificant after 100 and 500 cycles (p ≥ 0.116), a trend toward significance was observed after 1,000 cycles (p = 0.063), which became significant after 2,500 and 5,000 cycles (p ≤ 0.043).
From a biomechanical point of view, the locked intraosseous patellar nail may be an alternative to TBW using cannulated screws because of the higher interfragmentary stability provided at the articular fracture site.
A locked patellar nail for transverse patellar fractures achieved a stable osteosynthetic construct that may reduce hardware-associated complications because of its intraosseous positioning.
移位的横断髌骨骨折需要切开复位内固定。目前最先进的稳定技术是使用克氏针的张力带钢丝（TBW）或空心螺钉。这些技术与二次骨折移位、植入物迁移、植入物突出、伤口愈合障碍以及需要取出植入物的发生率较高有关。最近，开发了一种锁定的骨内髌骨钉原型。本研究的目的是研究与使用空心螺钉的 TBW 相比，这种钉的生物力学性能。
7 对新鲜冷冻的人体膝关节标本被剥去所有软组织，仅保留伸肌装置。创建一个横断骨折以模拟 OTA/AO 34-C1 型横断髌骨骨折。将标本对随机分配为使用空心螺钉的 TBW 固定或使用新型骨内钉固定。每个标本在通过拉动股四头肌并在 90°弯曲到完全膝关节伸展范围内模拟主动膝关节伸展和被动膝关节屈曲的情况下，进行 5,000 次循环测试。使用光学运动跟踪在 100、500、1,000、2,500 和 5,000 个测试循环后，研究骨折的前关节缘和关节缘位移以及围绕内外轴的断端旋转。
在评估的各自 5 个测试循环时间点内，与 TBW 相比，使用骨内钉固定后关节缘平均位移减少了 68%、60%、72%、76%和 81%。在 100 和 500 个循环后，差异仍然没有统计学意义（p≥0.116），在 1,000 个循环后观察到趋势（p=0.063），在 2,500 和 5,000 个循环后变得显著（p≤0.043）。
从生物力学的角度来看，与使用空心螺钉的 TBW 相比，锁定的骨内髌骨钉可能是一种替代方法，因为它在关节骨折部位提供了更高的断端稳定性。
对于横断髌骨骨折，使用锁定髌骨钉可实现稳定的内固定结构，由于其位于骨内，可能会减少与硬件相关的并发症。
