Toby Orthopaedics, Inc., Miami, FL, USA.
Musculoskeletal Publication and Analysis, Inc., Warsaw, IN, USA; Department of Bioengineering, University of Illinois at Chicago, Chicago, IL, USA.
J Shoulder Elbow Surg. 2020 Aug;29(8):1606-1614. doi: 10.1016/j.jse.2019.12.017. Epub 2020 Mar 5.
Proximal humeral fractures occur predominantly in elderly, osteoporotic individuals, especially women, with surgery performed in one-fifth. Proximal humeral locking plates are the gold standard operative treatment; however, complications are frequent, partially because of poor screw purchase in osteoporotic bone. A new method uses threaded posts through which threaded cross-elements orthogonally pass to create a 3-dimensional scaffold for bone engagement. We examined the pullout characteristics of the posts with (1 or 2) or without the cross-elements and tested 2 types of 3.5-mm cortical locking screws for comparison.
Low-density closed-cell polyurethane foam served as a model osteoporotic bone substrate. Following implantation in the substrate, the devices were axially loaded by a mechanical test system. Quantities of interest included failure mode, peak load, displacement to peak load, initial stiffness, and work expended.
The post groups outperformed the 3.5-mm screw groups, as expected. Relative to posts with no cross-elements, 1 and 2 cross-elements increased the peak load by 29% and 87% and increased the work to peak load by 126% and 343%, respectively. After reaching peak load, 1 and 2 cross-elements increased the work-resistance to further displacement by 158% and 330%, respectively.
Cross-elements significantly increased the ability of the threaded posts to resist axial displacement from a model osteoporotic bone substrate. This suggests that posts, used in conjunction with cross-elements, have the potential to enhance the stability of proximal humeral locking plates in osteoporotic bone.
肱骨近端骨折主要发生在老年骨质疏松患者中，尤其是女性，其中五分之一的患者需要手术治疗。肱骨近端锁定板是手术治疗的金标准；然而，并发症较为常见，部分原因是骨质疏松骨中螺钉固定不良。一种新方法使用带螺纹的销钉，这些销钉穿过螺纹交叉元件，形成一个用于骨结合的三维支架。我们研究了带有（1 或 2 个）或不带交叉元件的销钉的拔出特性，并测试了两种 3.5mm 皮质锁定螺钉进行比较。
低密度闭孔泡沫聚氨酯作为骨质疏松骨模型基底。装置植入基底后，通过机械测试系统对其进行轴向加载。感兴趣的参数包括失效模式、峰值载荷、达到峰值载荷的位移、初始刚度和耗功。
正如预期的那样，销钉组的性能优于 3.5mm 螺钉组。与不带交叉元件的销钉相比，1 个和 2 个交叉元件分别使峰值载荷增加了 29%和 87%，使达到峰值载荷的功增加了 126%和 343%。达到峰值载荷后，1 个和 2 个交叉元件使进一步位移的功阻力分别增加了 158%和 330%。
交叉元件显著提高了带螺纹销钉抵抗骨质疏松骨模型轴向位移的能力。这表明，带交叉元件的销钉有潜力增强骨质疏松性骨中肱骨近端锁定板的稳定性。
