背景:引入无茎植入物以防止与全肩关节置换术相关的一些与茎相关的并发症。虽然接受这些植入物的一般要求包括良好的骨质量条件,关于骨骼质量如何影响植入物性能的知识很少。这项研究的目的是评估年龄引起的骨密度变化的影响,作为骨骼质量的衡量标准,在使用3D有限元(FE)模型的五个解剖无茎肩植入物的主要稳定性中。
方法:考虑的植入物设计基于全局图标,Sidus,Simpliciti,SMR,和无茎植入物。在Solidworks中几乎模拟了肩关节置换术。来自两个年龄组的20名受试者的密度分布,20至40岁和60至80岁,从医学图像数据中检索并集成到单个肱骨几何形状的三维有限元模型中,在Abaqus开发,避免与几何特征相关的混杂因素。对于没有实心颈圈覆盖整个骨骼表面的设计,即,Sidus,Simpliciti,SMR,和植入植入物,考虑了肱骨头组件与骨骼之间的接触和非接触条件。考虑到与康复活动和艰巨任务相关的八种负荷情况,通过评估骨-植入物界面的微运动来评估主要稳定性。三个研究变量,考虑20μm,50μm,和150μm作为骨整合的阈值,用于结果的统计分析。
结果:与20-40岁年龄组相比,60-80岁年龄组的骨密度降低导致骨-植入物界面的微运动更大。基于全球图标和基于Inhance的设计对骨密度最不敏感,而基于Sidus的设计对骨密度最敏感。对于不具有实心套环的植入物,肱骨头部件和骨之间的接触的建立导致微运动减少。
结论:尽管年龄引起的骨密度下降导致FE模型的微运动增加,一些无茎肩植入物表现出良好的整体性能,无论考虑的骨整合阈值,提示仅年龄可能不是解剖全肩关节置换术的禁忌症。如果只考虑初级稳定性,结果表明,基于全局图标和基于Inhance的设计具有优越的性能。此外,在可行的情况下,肱骨头组件应与切除的骨表面接触。需要进一步的研究将这些结果与植入物的长期性能相结合,并提供更精确的建议。
BACKGROUND: Stemless implants were introduced to prevent some of the stem-related complications associated with the total shoulder arthroplasty. Although general requirements for receiving these implants include good bone quality conditions, little knowledge exists about how bone quality affects implant performance. The goal of this study was to evaluate the influence of age-induced changes in bone density, as a metric of bone quality, in the primary stability of five anatomic stemless shoulder implants using three-dimensional finite element (FE) models.
METHODS: The implant designs considered were based on the Global Icon, Sidus, Simpliciti, SMR, and Inhance stemless implants. Shoulder arthroplasties were virtually simulated in Solidworks. The density distributions of 20 subjects from two age groups, 20-40 and 60-80 years old, were retrieved from medical image data and integrated into three-dimensional FE models of a single humerus geometry, developed in Abaqus, to avoid confounding factors associated with geometric characteristics. For the designs which do not have a solid collar covering the entire bone surface, ie, the Sidus, Simpliciti, SMR, and Inhance implants, contact and noncontact conditions between the humeral head component and bone were considered. Primary stability was evaluated through the assessment of micromotions at the bone-implant interface considering eight load cases related to rehabilitation activities and demanding tasks. Three research variables, considering 20 μm, 50 μm, and 150 μm as thresholds for osseointegration, were used for a statistical analysis of the results.
RESULTS: The decreased bone density registered for the 60-80 age group led to larger micromotions at the bone-implant interface when compared to the 20-40 age group. The Global Icon-based and Inhance-based designs were the least sensitive to bone density, whereas the Sidus-based design was the most sensitive to bone density. The establishment of contact between the humeral head component and bone for the implants that do not have a solid collar led to decreased micromotions.
CONCLUSIONS: Although the age-induced decline in bone density led to increased micromotions in the FE models, some stemless shoulder implants presented good overall performance regardless of the osseointegration threshold considered, suggesting that age alone may not be a contraindication to anatomic total shoulder arthroplasty. If only primary stability is considered, the results suggested superior performance for the Global Icon-based and Inhance-based designs. Moreover, the humeral head component should contact the resected bone surface when feasible. Further investigation is necessary to combine these results with the long-term performance of the implants and allow more precise recommendations.