Ramos A, Duarte R J, Mesnard M
TEMA Center of Mechanical Technology and Automation, Department of Mechanical Engineering, University of Aveiro, Portugal; Université de Bordeaux, Institut de Mécanique et d'Ingénierie, CNRS UMR 5295, Talence, France.
TEMA Center of Mechanical Technology and Automation, Department of Mechanical Engineering, University of Aveiro, Portugal; Université de Bordeaux, Institut de Mécanique et d'Ingénierie, CNRS UMR 5295, Talence, France.
J Craniomaxillofac Surg. 2015 May;43(4):469-74. doi: 10.1016/j.jcms.2015.02.013. Epub 2015 Feb 24.
The fixation of commercial temporomandibular joint (TMJ) implant is accomplished by using screws, which, in some cases, can lead to loosening of the implant. The aim of this study was to predict the evolution of fixation success of a TMJ. Numerical models using a Christensen TMJ implant were developed to analyze strain distributions in the adjacent mandibular bone. The geometry of a human mandible was developed based on computed tomography (CT) scans from a cadaveric mandible on which a TMJ implant was subsequently placed. In this study, the five most important muscle forces acting were applied and the anatomical conditions replicated. The evolution of fixation was defined according to bone response methodology focused in strain distribution around the screws. Strain and micromotions were analyzed to evaluate implant stability, and the evolution process conduct at three different stages: start with all nine screws in place (initial stage); middle stage, with three screws removed (middle stage), and end stage, with only three screws in place (final stage). With regard to loosening, the implant success fixation changed the strains in the bone between 21% and 30%, when considering the last stage. The most important screw positions were #1, #7, and #9. It was observed that, despite the commercial Christensen TMJ implant providing nine screw positions for fixation, only three screws were necessary to ensure implant stability and fixation success.
商用颞下颌关节（TMJ）植入物的固定是通过使用螺钉来完成的，在某些情况下，这可能会导致植入物松动。本研究的目的是预测TMJ固定成功的演变情况。使用克里斯蒂安森TMJ植入物开发了数值模型，以分析下颌骨相邻部位的应变分布。基于对一具尸体下颌骨的计算机断层扫描（CT）扫描构建了人类下颌骨的几何模型，随后在该下颌骨上放置了TMJ植入物。在本研究中，施加了作用最显著的五种肌肉力量并复制了解剖条件。根据关注螺钉周围应变分布的骨反应方法来定义固定的演变情况。分析应变和微运动以评估植入物的稳定性，并且在三个不同阶段进行演变过程：开始时所有九个螺钉就位（初始阶段）；中间阶段，移除三个螺钉（中间阶段）；最后阶段，仅三个螺钉就位（最终阶段）。关于松动问题，在考虑最后阶段时，植入物成功固定使骨中的应变在21%至30%之间变化。最重要的螺钉位置是#1、#7和#9。据观察，尽管商用克里斯蒂安森TMJ植入物提供了九个用于固定的螺钉位置，但仅需三个螺钉就能确保植入物的稳定性和固定成功。
