Narrative review of influence of prosthesis lateralization on clinical outcomes in reverse shoulder arthroplasty: glenoid vs. humerus vs. combined.

Background and objective: Reverse shoulder arthroplasty has become a common orthopaedic procedure, with a growing number of cases annually for multiple indications, such as rotator cuff arthropathy, osteoarthritis, or fractures of the proximal humerus, to reduce pain and restore shoulder mobility. Prosthesis design and various recent improvements aim to enhance range of motion (ROM) and stability and to limit component loosening and other potential complications. Many of these well-known issues could theoretically be improved by glenoid, humeral, or combined component lateralization. The objective of this article is to provide an up-to-date literature overview, present available options, and discuss the rationale behind lateralization of certain components, as well as their combined impact on outcomes of reverse shoulder arthroplasty.

Methods: PubMed and Scopus databases from 2003 to 2023 were searched and screened for studies, including systematic reviews, on the influence of glenoid, humeral, and combined component lateralization that served for narrative review of rationale behind such design.

Key content and findings: Currently, a number of computer simulations, anatomic studies, and limited clinical references aim to support the rationale behind glenoid augmentation, variable humeral neck-shaft angle (NSA), or humeral tray design.

Conclusions: The utility of lateralization has not yet been clinically established. Randomized, long-term clinical outcome studies are still needed to reach a verdict going beyond surgeon preference and case-specific indications.