Impact of the critical shoulder angle on shoulder arthroplasty outcomes: a systematic review

Introduction The critical shoulder angle (CSA), a radiographic measure reflecting the relationship between glenoid inclination and lateral acromial coverage, has garnered increased attention for its potential influence on shoulder arthroplasty outcomes. Despite its significance, the impact of CSA on shoulder arthroplasty outcomes remains uncertain, as conflicting evidence persists in the literature. The purpose of this systematic review was to conduct a comprehensive analysis of the available literature, focusing on the functional outcomes and complications associated with CSA in the context of shoulder arthroplasty. Materials and methods This systematic review was conducted in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines.The English-language articles were screened from databases such as PubMed, EMBASE, the Web of Science, and the Cochrane Library Database. Studies involving patients who underwent shoulder arthroplasty and evaluated the influence of CSA on complications, clinical scores, and range of motion (ROM) were included. The data were independently extracted by two authors, and evidence quality and bias risk were assessed collectively. Results Nine studies were included—six cohort studies, one case series, and two case–control studies. When a meta-analysis was not conducted, a consistent trend emerged. A higher CSA was linked to an increased risk of revision surgery after shoulder arthroplasty, primarily due to complications such as prosthetic loosening, glenoid lucency, and secondary rotator cuff failure. However, no substantial correlation was found between the CSA and postoperative clinical score or ROM. Conclusions A higher CSA correlates with an increased revision rate following shoulder arthroplasty, primarily due to complications such as prosthetic loosening. However, the CSA was not significantly correlated with postoperative clinical score or ROM. This finding underscores the value of the CSA as a predictive factor for revision risk while emphasizing its limited impact on clinical outcomes and shoulder joint ROM. Level of evidence Level IV; Systematic Review.