Department of Trauma Surgery, General Hospital of Vienna, Waehringer Guertel 18-20, 1090, Vienna, Austria.
Center for Medical Physics and Biomedical Engineering, Medical University of Vienna, Waehringer Guertel 18-20, A-1090, Vienna, Austria.
J Mater Sci Mater Med. 2020 Oct 21;31(11):92. doi: 10.1007/s10856-020-06445-y.
Screw osteosynthesis using headless compression screws has become the accepted gold standard for the surgical treatment of scaphoid fractures. Optimal screw specifications remain controversially discussed. We aimed to investigate the influence of bone model composition on screw stability tests using headless compression screws in different scaphoid fracture models. We conducted pull-out tests using Acutrak2mini, HCS, HKS, HBS, Herbert/Whipple and Twinfix screws. To imitate cortical and cancellous bone, two-layer polyurethane (PU) models with two distinct densities were produced. The cylinders were cut at different positions to replicate fracture localisations at increasing distances. The maximum pull-out force required to achieve up to 1 mm of pull-out distance (N) was measured. Acutrak2mini and HCS followed by Twinfix showed the greatest average pull-out forces. N was, on average, greater in the cortico-cancellous model than in the cancellous cylinder with the Acutrak2mini and the Herbert/Whipple screws, while it was the least with the HBS and the Twinfix screws; there were also differences between the HCS and HKS. There were no differences between the different fracture simulations in the synthesis strength using either the HKS or HBS. The pull-out forces of the HCS and Twinfix remained high also in simulations with the smaller screw base fragments. Varying imitations of cancellous and cortico-cancellous bone and fracture localisation reveal important information about the ex vivo strength of screw syntheses. The grip of the cortical structure should be used with the screws that fit more firmly in cortico-cancellous bone.
无头加压螺钉固定已成为治疗舟状骨骨折的金标准。最佳螺钉规格仍存在争议。我们旨在研究使用无头加压螺钉在不同舟状骨骨折模型中进行螺钉稳定性测试时，骨模型成分的影响。我们使用 Acutrak2mini、HCS、HKS、HBS、Herbert/Whipple 和 Twinfix 螺钉进行了拔出试验。为了模拟皮质骨和松质骨，我们制作了具有两种不同密度的双层聚氨酯（PU）模型。将圆柱体切割成不同位置，以模拟不同距离的骨折定位。测量达到 1mm 拔出距离（N）所需的最大拔出力。Acutrak2mini 和 HCS 紧随其后的是 Twinfix 显示出最大的平均拔出力。与 Acutrak2mini 和 Herbert/Whipple 螺钉相比，皮质-松质模型中的 N 平均高于松质圆柱模型，而与 HBS 和 Twinfix 螺钉相比，N 最小；HCS 和 HKS 之间也存在差异。在使用 HKS 或 HBS 的情况下，不同骨折模拟之间的合成强度没有差异。即使在较小的螺钉基底碎片的模拟中，HCS 和 Twinfix 的拔出力仍然很高。不同的松质和皮质-松质骨的模拟以及骨折定位揭示了螺钉合成的体外强度的重要信息。皮质结构的抓地力应与更牢固地固定在皮质-松质骨中的螺钉一起使用。
