Moazen Mehran, Mak Jonathan H, Jones Alison C, Jin Zhongmin, Wilcox Ruth K, Tsiridis Eleftherios
Institute of Medical and Biological Engineering, University of Leeds, Leeds, UK.
Proc Inst Mech Eng H. 2013 Jul;227(7):746-56. doi: 10.1177/0954411913483259. Epub 2013 Apr 4.
Computational modelling of the screw-bone interface in fracture fixation constructs is challenging. While incorporating screw threads would be a more realistic representation of the physics, this approach can be computationally expensive. Several studies have instead suppressed the threads and modelled the screw shaft with fixed conditions assumed at the screw-bone interface. This study assessed the sensitivity of the computational results to modelling approaches at the screw-bone interface. A new approach for modelling this interface was proposed, and it was tested on two locking screw designs in a diaphyseal bridge plating configuration. Computational models of locked plating and far cortical locking constructs were generated and compared to in vitro models described in prior literature to corroborate the outcomes. The new approach led to closer agreement between the computational and the experimental stiffness data, while the fixed approach led to overestimation of the stiffness predictions. Using the new approach, the pattern of load distribution and the magnitude of the axial forces, experienced by each screw, were compared between the locked plating and far cortical locking constructs. The computational models suggested that under more severe loading conditions, far cortical locking screws might be under higher risk of screw pull-out than the locking screws. The proposed approach for modelling the screw-bone interface can be applied to any fixation involved application of screws.
骨折固定结构中螺钉与骨界面的计算建模具有挑战性。虽然纳入螺纹将更真实地反映物理情况，但这种方法在计算上可能成本高昂。相反，一些研究忽略了螺纹，在假设螺钉与骨界面为固定条件的情况下对螺钉杆进行建模。本研究评估了计算结果对螺钉与骨界面建模方法的敏感性。提出了一种对该界面进行建模的新方法，并在骨干桥接钢板配置中的两种锁定螺钉设计上进行了测试。生成了锁定钢板和远皮质锁定结构的计算模型，并与先前文献中描述的体外模型进行比较，以证实结果。新方法使计算刚度数据与实验刚度数据之间的一致性更高，而固定方法导致刚度预测值被高估。使用新方法，比较了锁定钢板和远皮质锁定结构中每个螺钉所承受的载荷分布模式和轴向力大小。计算模型表明，在更严苛的加载条件下，远皮质锁定螺钉可能比锁定螺钉面临更高的螺钉拔出风险。所提出的螺钉与骨界面建模方法可应用于任何涉及螺钉应用的固定。
