Aix Marseille University, CNRS, ISM, Marseille, France; APHM, Institute for Locomotion, Department of Orthopaedics and Traumatology, St Marguerite Hospital, Marseille, France.
NewClip Technics, Haute-Goulaine, France.
Clin Biomech (Bristol). 2021 Feb;82:105274. doi: 10.1016/j.clinbiomech.2021.105274. Epub 2021 Jan 14.
Four-corner arthrodesis, which involves fusing four carpal bones while removing the scaphoid bone, is a standard surgery for the treatment of advanced stages of wrist arthritis. Nowadays, it can be performed using a dorsal approach by fixing a plate to the bones and a new radial approach is in development. To date, there is no consensus on the biomechanically optimal and most reliable surgical construct for four-corner arthrodesis.
To evaluate them biomechanically and thus assist the surgeon in choosing the best implant orientation, radial or dorsal, the two different four-corner arthrodesis surgical constructs were virtually simulated on a 3D finite element model representing all major structures of the wrist. Two different realistic load sets were applied to the model, representing common tasks for the elderly.
Results consistency was assessed by comparing with the literature the force magnitude computed on the carpal bones. The Von Mises stress distribution in the radial and dorsal plates were calculated. Stress concentration was located at the plate-screw interface for both surgical constructs, with a maximum stress value of 413 MPa for the dorsal plate compared to 326 MPa for the radial plate, meaning that the stress levels are more unfavourable in the dorsal approach.
Although some bending stress was found in one load case, the radial plate was mechanically more robust in the other load case. Despite some limitations, this study provides, for the first time, quantified evidence that the newly developed radial surgical construct is mechanically as efficient as the dorsal surgical construct.
四角融合术，即融合四个腕骨并切除舟状骨，是治疗腕关节炎晚期的标准手术。如今，可以通过在骨头上固定钢板来采用背侧入路，同时一种新的桡侧入路也在开发中。迄今为止，对于四角融合术，在生物力学上最佳和最可靠的手术构建方式还没有达成共识。
为了评估其生物力学性能，从而帮助外科医生选择最佳的植入物方向，即桡侧或背侧，在代表腕部所有主要结构的 3D 有限元模型上对两种不同的四角融合术手术构建方式进行了虚拟模拟。对模型施加了两种不同的现实负荷，代表老年人的常见任务。
通过将计算得出的腕骨受力大小与文献进行比较，评估了结果的一致性。计算了桡侧和背侧钢板的 Von Mises 应力分布。在两种手术构建方式中，应力集中都位于钢板-螺钉界面，背侧钢板的最大应力值为 413 MPa，而桡侧钢板为 326 MPa，这意味着背侧入路的应力水平更不利。
尽管在一种负荷情况下发现了一些弯曲应力，但在另一种负荷情况下，桡侧钢板在力学上更坚固。尽管存在一些局限性，但这项研究首次提供了定量证据，证明新开发的桡侧手术构建方式在力学上与背侧手术构建方式一样有效。
