Arthroscopic ankle arthrodesis (AAA) is a standard surgical method for the treatment of advanced traumatic ankle arthritis and has become more popular due to its advantages. To fix the tibiotalar joint, the use of three percutaneous screws is considered to have better mechanical stability than the use of two screws. However, it is sometimes difficult to insert three screws because they might block each other due to the small area of the tibiotalar joint surface and the large diameter of the screws; few articles illustrate how to insert three screws without the screws disturbing each other. The purpose of this study is to explore possible screw configurations of tripod fixation in arthroscopic ankle arthrodesis that avoid the collision of screws and yield better biomechanical performance. We used the finite element method to examine the impact of different screw positions and orientations on the biomechanical characteristics of a three-dimensional (3D) ankle model. Maximum and average micromotion, pressure on the articular surface, and von Mises stress values of the tibia and the talus were used to evaluate the initial stability of the ankle. Five kinds of three-screw configurations were identified, and finite element analysis results suggested that configurations with the posteromedial home-run screw presented lower micromotion (maximum, 17.96 ± 7.49 μm versus 22.52 ± 12.8 μm; mean, 4.88 ± 1.89 μm versus 5.19 ± 1.92 μm) (especially configuration 3) and better screw distributions on the articular surface than those with the posterolateral home-run screw. Screw configurations with the posteromedial home-run screw avoid collision and are more biomechanically stable than those with the posterolateral home-run screw. Thus, inserting the home-run screw through the posteromedial approach is recommended for clinical practice.

中文翻译：

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用三螺钉固定的关节镜检查踝关节固定术的初始稳定性的有限元分析：后内侧vs后外侧自攻螺钉。

关节镜检查踝关节固定术（AAA）是治疗晚期外伤性踝关节炎的标准手术方法，由于其优点而变得越来越流行。为了固定胫距关节，使用三个经皮螺钉比使用两个螺钉具有更好的机械稳定性。但是，有时很难插入三个螺钉，因为由于胫距骨关节面的面积小和螺钉的直径大，它们可能会相互阻塞。很少有文章说明如何在不相互干扰的情况下插入三颗螺钉。这项研究的目的是探讨关节镜踝关节固定术中三脚架固定的可能螺钉构造，该结构可避免螺钉碰撞并产生更好的生物力学性能。我们使用有限元方法来检查不同的螺钉位置和方向对三维（3D）踝关节模型的生物力学特性的影响。使用最大和平均微动，关节表面的压力以及胫骨和距骨的von Mises应力值来评估踝关节的初始稳定性。鉴定了五种三螺杆配置，有限元分析结果表明，采用后内侧自攻螺钉的配置具有较低的微动（最大17.96±7.49μm对22.52±12.8μm；平均4.88±1.89μm对5.19±与使用后外侧自攻螺钉的患者相比，其在关节表面的螺钉分布更好（尤其是1.92μm）（尤其是配置3）。与后外侧本垒打螺钉相比，采用后内侧本垒打螺钉的螺钉配置避免了碰撞，并且在生物力学上更加稳定。因此，对于临床实践，建议通过后内侧入路插入本垒打螺钉。