Although the primary stability of joint implants is fundamental for successful osseointegration, little is know about this issue in the context of stemless shoulder implants. Considering 3D finite element models, the purpose of this study was to evaluate the primary stability of five stemless designs, based on the Sidus, SMR, Simpliciti, Eclipse, and Global Icon stemless systems. Three alternative bone quality conditions were considered for cancellous bone. For the Sidus, SMR, and Simpliciti designs, which do not possess a collar that sits on the cortical rim of the humeral resected surface, contact and no contact conditions were considered between the bone surface and the humeral head components. Micromotions at bone-implant interfaces promoting osseointegration were computed as a measure of primary stability for eight load cases consisting of peak in vivo joint loads measured during selected upper limb activities. Under good bone quality conditions, all stemless designs presented micromotions below 150 μm. The Eclipse-based and Global-Icon based designs were the least sensitive to bone quality. Stemless designs presenting a solid collar or contact between the humeral head component and bone provided more stability. Overall, the Eclipse-based and Global Icon-based designs presented the best performance from the primary stability point of view. However, if bone adaptation data available in the literature are considered along with the primary stability data computed here, the Global Icon-based design, as well as other designs, might be considered superior long-term options due to their better compromise between primary stability and impact on bone adaptation.

尽管关节植入物的主要稳定性是成功骨整合的基础，但在无茎肩部植入物的情况下，对该问题知之甚少。考虑3D有限元模型，本研究的目的是评估基于Sidus，SMR，Simpliciti，Eclipse和Global Icon无杆系统的五种无杆设计的主要稳定性。对于松质骨，考虑了三种替代的骨质状况。对于Sidus，SMR和Simpliciti设计，因为它们不具有位于肱骨切除表面皮质边缘上的项圈，因此在骨表面与肱骨头组件之间没有接触，也没有考虑接触条件。计算了八种负荷情况下骨骼与植入物界面促进骨整合的微动，以衡量其主要稳定性，包括在选定的上肢活动期间测得的体内关节峰值负荷。在良好的骨骼质量条件下，所有无茎设计均表现出低于150μm的微动。基于Eclipse和基于Global-Icon的设计对骨骼质量最不敏感。无柄设计在肱骨头组件和骨头之间呈现出坚固的衣领或接触，提供了更高的稳定性。总体而言，从主要稳定性的角度来看，基于Eclipse和基于Global Icon的设计提供了最佳性能。但是，如果考虑文献中提供的骨骼适应性数据以及此处计算的主要稳定性数据，则基于全局图标的设计以及其他设计，