Background and Objective

Tibiofibular syndesmotic injuries may cause degenerative changes, reduction in ankle function and compromising ankle stability. Different fixation techniques try to restore its functionality. Screw-fixation is the gold-standard. Recently, suture-button fixation has aroused the attention because it allows for physiologic micromotion while maintaining an accurate reduction. The aim of this study is to compare the biomechanical behaviour of both fixation techniques using the finite element method.

Methods

A three-dimensional finite element model of the tibiofibular joint was reconstructed simulating the intact ankle and the injured syndesmosis. Then, different methods of syndesmosis fixation were analysed: screws (number of cortices, number of screws and distance between screws) and suture buttons (single, double parallel and double divergent with a sensitivity analysis on the pretension forces) configuration. Ligaments and cartilages were included and simulated as spring elements. Physiological loads during stance phase were simulated.

Results

Syndesmosis widening and von Mises stresses were computed. Syndesmosis widening in the injured configuration compromised joint stability (2.06 mm), whereas using a single quadricortical screw (0.18 mm) stiffened the joint. Syndesmosis widening using suture-buttons were closer to syndesmosis widening of the intact ankle configuration (0.97 mm). Von Mises stresses were higher for the titanium screws than for the suture buttons.

Conclusions

A detailed biomechanical comparison among different syndesmotic fixation was performed. Suture buttons have advantages with regard to syndesmosis widening in comparison to screw fixation. This fact supports the good long-term clinical results obtained with suture buttons fixation. The proposed methodology could be an efficient tool for preoperative planning.

中文翻译：

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通过有限元分析对联合固定技术进行生物力学评估：螺钉与缝合按钮

背景与目的

胫腓联合损伤可能导致退行性变化、踝关节功能下降和踝关节稳定性受损。不同的固定技术试图恢复其功能。螺钉固定是金标准。最近，缝合按钮固定引起了人们的注意，因为它允许生理微动，同时保持准确的复位。本研究的目的是使用有限元方法比较两种固定技术的生物力学行为。

方法

重建胫腓关节的三维有限元模型，模拟完整的踝关节和受伤的联合。然后，分析了联合固定的不同方法：螺钉（皮质数量、螺钉数量和螺钉之间的距离）和缝合纽扣（单、双平行和双发散，对预紧力进行敏感性分析）配置。韧带和软骨被包括并模拟为弹簧元件。模拟站立阶段的生理负荷。

结果

计算了联合加宽和von Mises 应力。受伤结构中的联合加宽会影响关节稳定性（2.06 毫米），而使用单个四皮质螺钉（0.18 毫米）会使关节变硬。使用缝合纽扣加宽的关节联合更接近于完整踝关节结构的联合加宽（0.97 毫米）。钛螺钉的 Von Mises 应力高于缝合纽扣。

结论

进行了不同联合固定之间的详细生物力学比较。与螺钉固定相比，缝合纽扣在扩大关节联合方面具有优势。这一事实支持缝合纽扣固定获得的良好长期临床结果。所提出的方法可以成为术前计划的有效工具。