Orassi Vincenzo, Fischer Heilwig, Duda Georg N, Heiland Max, Checa Sara, Rendenbach Carsten
Berlin Institute of Health at Charité-Universitätsmedizin Berlin, Julius Wolff Institute, Berlin, Germany.
Berlin-Brandenburg School for Regenerative Therapies, Berlin, Germany.
Front Bioeng Biotechnol. 2022 Feb 10;9:803103. doi: 10.3389/fbioe.2021.803103. eCollection 2021.
Titanium fixation devices are the gold standard for the treatment of mandibular fractures; however, they present serious limitations, such as non-degradability and generation of imaging artifacts. As an alternative, biodegradable magnesium alloys have lately drawn attention due to their biodegradability and biocompatibility. In addition, magnesium alloys offer a relatively high modulus of elasticity in comparison to biodegradable polymers, being a potential option to substitute titanium in highly loaded anatomical areas, such as the mandible. This study aimed to evaluate the biomechanical competence of magnesium alloy WE43 plates for mandibular fracture fixation in comparison to the clinical standard or even softer polymer solutions. A 3D finite element model of the human mandible was developed, and four different fracture scenarios were simulated, together with physiological post-operative loading and boundary conditions. In a systematic comparison, the material properties of titanium alloy Ti-6Al-4V, magnesium alloy WE43, and polylactic acid (PLA) were assigned to the fixation devices, and two different plate thicknesses were tested. No failure was predicted in the fixation devices for any of the tested materials. Moreover, the magnesium and titanium fixation devices induced a similar amount of strain within the healing regions. On the other hand, the PLA devices led to higher mechanical strains within the healing region. Plate thickness only slightly influenced the primary fixation stability. Therefore, magnesium alloy WE43 fixation devices seem to provide a suitable biomechanical environment to support mandibular fracture healing in the early stages of bone healing. Magnesium WE43 showed a biomechanical performance similar to clinically used titanium devices with the added advantages of biodegradability and radiopacity, and at the same time it showed a remarkably higher primary stability compared to PLA fixation devices, which appear to be too unstable, especially in the posterior and more loaded mandibular fracture cases.
钛固定装置是治疗下颌骨骨折的金标准；然而，它们存在严重的局限性，如不可降解性和产生成像伪影。作为替代方案，可生物降解的镁合金因其生物可降解性和生物相容性最近受到了关注。此外，与可生物降解聚合物相比，镁合金具有相对较高的弹性模量，是在高负荷解剖区域（如下颌骨）替代钛的潜在选择。本研究旨在评估镁合金WE43接骨板用于下颌骨骨折固定的生物力学性能，并与临床标准甚至更柔软的聚合物解决方案进行比较。建立了人类下颌骨的三维有限元模型，模拟了四种不同的骨折情况，以及术后的生理负荷和边界条件。在系统比较中，将钛合金Ti-6Al-4V、镁合金WE43和聚乳酸（PLA）的材料特性赋予固定装置，并测试了两种不同的板厚。对于任何测试材料，固定装置均未预测到失效。此外，镁和钛固定装置在愈合区域内引起的应变数量相似。另一方面，PLA装置在愈合区域内导致更高的机械应变。板厚仅对初始固定稳定性有轻微影响。因此，镁合金WE43固定装置似乎能提供合适的生物力学环境，以支持骨愈合早期的下颌骨骨折愈合。镁合金WE43表现出与临床使用的钛装置相似的生物力学性能，具有生物可降解性和射线不透性的额外优点，同时与PLA固定装置相比，它表现出显著更高的初始稳定性，PLA固定装置似乎过于不稳定，尤其是在下颌骨后部和负荷更大的骨折病例中。
