Martínez-Fortún Gabriel, Yánez Alejandro, Cuadrado Alberto
Department of Mechanical Engineering, University of Las Palmas de Gran Canaria, 35017 Las Palmas de Gran Canaria, Spain.
Bioengineering (Basel). 2024 Oct 14;11(10):1024. doi: 10.3390/bioengineering11101024.
Polyaxial locking systems are widely used for strategic surgical placement, particularly in cases of osteoporotic bones, comminuted fractures, or when avoiding pre-existing prosthetics. However, studies suggest that polyaxiality negatively impacts system stiffness. We hypothesize that a new plate design, combining a narrow plate with asymmetric holes and polyaxial capabilities, could outperform narrow plates with symmetric holes. Three configurations were tested: Group 1 with six orthogonal screws, and Groups 2 and 3 with polyaxiality in the longitudinal and transverse axes, respectively. A biomechanical model assessed the bone/plate/screw interface under cyclic compression (5000 cycles) and torsion loads until failure. Screws were inserted up to 10° angle. None of the groups showed a significant loss of stiffness during compression ( > 0.05). Group 1 exhibited the highest initial stiffness, followed by Group 3 (<29%) and Group 2 (<35%). In torsional testing, Group 1 achieved the most load cycles (29.096 ± 1.342), while Groups 2 and 3 showed significantly fewer cycles to failure (6.657 ± 3.551 and 4.085 ± 1.934). These results confirm that polyaxiality, while beneficial for surgical placement, reduces biomechanical performance under torsion. Despite this, no group experienced complete decoupling of the screw-plate interface, indicating the robustness of the locking mechanism even under high stress.
多轴锁定系统广泛应用于关键的手术植入，特别是在骨质疏松性骨骼、粉碎性骨折的情况下，或在避免已有假体的情况下。然而，研究表明多轴性会对系统刚度产生负面影响。我们假设一种新的钢板设计，将窄钢板与不对称孔和多轴功能相结合，可能优于具有对称孔的窄钢板。测试了三种配置：第1组有六个正交螺钉，第2组和第3组分别在纵向和横向轴上具有多轴性。一个生物力学模型在循环压缩（5000次循环）和扭转载荷直至失效的情况下评估骨/钢板/螺钉界面。螺钉以高达10°的角度插入。在压缩过程中，没有一组显示出明显的刚度损失（>0.05）。第1组表现出最高的初始刚度，其次是第3组（<29%）和第2组（<35%）。在扭转测试中，第1组实现了最多的载荷循环次数（29.096±1.342），而第2组和第3组的失效循环次数明显较少（6.657±3.551和4.085±1.934）。这些结果证实，多轴性虽然有利于手术植入，但会降低扭转时的生物力学性能。尽管如此，没有一组经历螺钉-钢板界面的完全脱开，这表明即使在高应力下锁定机制也很稳固。
