Stene G M, Frigg R, Schlegel U, Swiontkowski M
AO/ASIF Research Institute, Davos Platz.
Injury. 1992;23 Suppl 3:S9-27. doi: 10.1016/0020-1383(92)90004-c.
In open fractures especially in those with severe soft tissue damage, fracture stabilisation is best achieved by using external fixators. There are some intrinsic complications which occur during classical external pin fixation. To overcome the problem of pin track infection and vascular damage from drilling, the Pinless external fixator was developed. It is based on the idea of a forceps with trocar points, which only penetrate the bone cortex superficially. The function of the device was tested in two mechanical trials and two in vitro tests in which one pinless clamp was put under a controlled load of 50 N, 150 cycles/day and studied over a 5 week period in sheep. The loads and time range of the experiment were chosen to simulate a temporary fracture stabilisation in a patient not bearing weight. The main question to be answered was whether the Pinless external fixator would be able to maintain stable fixation. Furthermore, it was to determine the changes at the trocar-to-bone interface. The clamp was found to maintain 72% of the initially applied clamping force after 5 weeks of in vivo application and it was found to be tight at removal. Some decrease of clamping force was found during the first 20 days and then the force tended to level off. There was no slippage nor did the clamp penetrate the cortex. There were no obvious signs of infection around the trocar-holes and in the bacterial tests no pathological cultures were grown. Histology revealed very localised bone reactions, the indentation caused by the trocar tips being only 1.2 mm deep. The study concludes, as far as could be ascertained from these tests, that it is safe to use pinless external fixation for temporary fracture fixation.
在开放性骨折中，尤其是那些伴有严重软组织损伤的骨折，使用外固定器能最好地实现骨折稳定。在传统的外固定针固定过程中会出现一些固有并发症。为了克服针道感染和钻孔导致的血管损伤问题，无针外固定器应运而生。它基于带有套管针尖端的镊子的理念，套管针尖端仅浅度穿透骨皮质。该装置的功能在两项力学试验和两项体外试验中进行了测试，其中一个无针夹具在50 N的控制载荷下，每天150次循环，并在绵羊身上进行了为期5周的研究。选择该实验的载荷和时间范围是为了模拟非负重患者的临时骨折稳定情况。要回答的主要问题是无针外固定器是否能够保持稳定的固定。此外，还要确定套管针与骨界面处的变化。结果发现，在体内应用5周后，夹具保持了最初施加的夹紧力的72%，并且在移除时发现它仍然很紧。在最初的20天内发现夹紧力有所下降，然后趋于平稳。没有出现滑动，夹具也没有穿透皮质。在套管针孔周围没有明显的感染迹象，在细菌测试中也没有培养出病理培养物。组织学显示骨反应非常局限，套管针尖端造成的压痕仅1.2毫米深。根据这些测试可以确定，该研究得出结论，使用无针外固定进行临时骨折固定是安全的。
