Greisberg Justin, Vosseller J Turner, Ferry Chris, Nash Calvin, Gardner Thomas R
Department of Orthopaedic Surgery, Columbia University Medical Center, 622 West 168th St, PH 11th floor, New York, NY, 10032, USA.
Int Orthop. 2015 Nov;39(11):2267-74. doi: 10.1007/s00264-015-2855-y. Epub 2015 Jul 23.
When performing hindfoot arthodeses, one goal of fixation is often to achieve compression across the joint. Traditional lag screws are applied eccentrically, providing compression more on the edge of the fusion. A new technique, using a post in one bone and a lag screw through the post to the other bone, may offer better compression across more of the joint.
There are three parts to this study comparing a post-and-screw construct to traditional lag screws. Synthetic bone models, representative of the talonavicular joint, were created and assessed for biomechanical measures of compression. Next, the post-and-screw construct was tested in cadavers, under conditions representing early weight bearing after arthrodesis surgery. Finally, 18 patients who had a talonavicular fusion with a post-and-screw construct with one surgeon were compared to the previous 18 patients fixed with traditional screws.
In the synthetic bone model, the post-and-screw construct brought the centre of compression closer to the centre of the joint, suggesting compression was less eccentric. Neither traditional screws nor the post-and-screw construct were sufficiently strong to resist early weight bearing forces in cadaver specimens. In the clinical comparison, four patients had a painful nonunion when fixed with traditional screws, compared to none in the post-and-screw construct.
A post-and-screw construct spreads the forces of compression more uniformly across an arthrodesis, even when placed eccentrically. Although not all the biomechanical measures were superior, the post-and-screw construct achieved higher levels of successful fusion in patients. This technology may offer improved outcomes in some clinical scenarios and deserves further study.
Level 3.
在进行后足关节融合术时，固定的一个目标通常是实现关节面的加压。传统拉力螺钉的应用是偏心的，在融合边缘提供更多的加压。一种新技术，即在一块骨中使用一个柱状物，并通过该柱状物向另一块骨拧入拉力螺钉，可能在更多的关节面上提供更好的加压效果。
本研究分三个部分，将柱状物-螺钉结构与传统拉力螺钉进行比较。制作了代表距舟关节的合成骨模型，并对其加压的生物力学指标进行评估。接下来，在尸体上测试柱状物-螺钉结构，测试条件模拟关节融合术后早期负重情况。最后，将一位外科医生使用柱状物-螺钉结构进行距舟关节融合的18例患者与之前使用传统螺钉固定的18例患者进行比较。
在合成骨模型中，柱状物-螺钉结构使加压中心更靠近关节中心，表明加压的偏心性更小。在尸体标本中，传统螺钉和柱状物-螺钉结构都不足以抵抗早期负重力量。在临床比较中，使用传统螺钉固定的患者中有4例出现疼痛性骨不连，而使用柱状物-螺钉结构的患者中无此情况。
即使偏心放置，柱状物-螺钉结构也能在关节融合面上更均匀地分散加压力量。虽然并非所有生物力学指标都更优，但柱状物-螺钉结构在患者中实现了更高水平的成功融合。这项技术在某些临床情况下可能会带来更好的结果，值得进一步研究。
3级。
