Department of Mechanics of Materials and Structures, Faculty of Civil and Environmental Engineering, Gdańsk University of Technology, Gdańsk, Poland.
II Clinic of Orthopaedics and Kinetic Organ Traumatology, Medical University of Gdansk, Gdańsk, Poland.
PLoS One. 2021 Dec 1;16(12):e0260572. doi: 10.1371/journal.pone.0260572. eCollection 2021.
The purpose of this study was to biomechanically compare the stability of first metatarsophalangeal (MTP1) joint arthrodesis with dorsally and medially positioned plates.
A physical model of the MTP1 joint consists of printed synthetic bones, a titanium locking plate and screws. In the experiments, samples with dorsally and medially positioned plates were subjected to loading of ground load character in a universal testing machine. Force-displacement relations and relative displacements of bones were recorded. The obtained results were used to validate the corresponding finite element models of the MTP1 joint. Nonlinear finite element simulations of the toe-off phase of gait were performed to determine the deformation and stress state in the MTP1 joint for two positions of the plate.
In numerical simulations, the maximum displacement in the dorsal direction was noticed at the tip of the distal phalanx and was equal to 19.6 mm for the dorsal plate and 9.63 mm for the medial plate for a resultant force of 150 N. Lower relative bone displacements and smaller plastic deformation in the plate were observed in the model with the medial plate. Stress values were also smaller in the medially positioned plate and locking screws compared to fixation with the dorsal plate.
A medially positioned locking plate provides better stability of the MTP1 joint than a dorsally positioned plate due to greater vertical bending stiffness of the medial plate. Smaller relative bone displacements observed in fixation with the medial plate may be beneficial for the bone healing process. Moreover, lower stress values may decrease the risk of complications associated with hardware failure.
本研究旨在从生物力学角度比较跖趾关节（MTP1）背侧和内侧置板的稳定性。
MTP1 关节的物理模型由打印合成骨、钛锁定板和螺钉组成。在实验中，对背侧和内侧置板的样本进行了万能试验机下地载特征加载。记录了力-位移关系和骨骼的相对位移。所获得的结果用于验证 MTP1 关节的相应有限元模型。对步态离地阶段进行非线性有限元模拟，以确定两种板位置下 MTP1 关节的变形和应力状态。
在数值模拟中，在远节趾骨的尖端处观察到最大的背向位移，对于背侧板，其值为 19.6mm，对于内侧板，其值为 9.63mm，对于 150N 的合力。在有内侧板的模型中，观察到相对较小的骨位移和较小的板塑性变形。与背侧固定相比，内侧置板和锁定螺钉的应力值也较小。
由于内侧板具有更大的垂直弯曲刚度，内侧锁定板比背侧板能更好地稳定 MTP1 关节。在与内侧板固定时观察到的相对较小的骨位移可能有利于骨愈合过程。此外，较低的应力值可能会降低与硬件故障相关的并发症风险。
