Does lateralization and distalization affect revision rates and patient experience in primary stemmed reverse total shoulder arthroplasty?

Background: This study examined the association between distalization and lateralization of implant components and revision outcomes and patient-reported outcome measures (PROMs) following primary total stemmed reverse shoulder arthroplasty (rTSA) using data from a national arthroplasty registry. Materials and methods: All primary total stemmed modular rTSA procedures (excluding custom implants) recorded between January 1, 2015, and December 31, 2023, were identified. A total of 25,837 primary rTSA procedures were included. Procedures were classified into 6 construct groups based on humeral and glenoid component features associated with distalization and/or lateralization. Kaplan–Meier methods were used to estimate cumulative percent revision. Cox proportional hazards models estimated adjusted hazard ratios, controlling for age, sex, American Society of Anesthesiologists score, body mass index, primary diagnosis, glenosphere size, and glenoid morphology. Subgroup analyses were performed for inlay and onlay humeral configurations. PROMs collected from November 2018 were analyzed in a subset of patients. Results: Constructs incorporating humeral distalization demonstrated higher revision rates beyond 1.5 years compared with standard components (P = .002). Augmented glenoid baseplates were associated with lower early revision rates within 3 months (P = .002). Onlay designs incorporating distalization and/or lateralization showed increased revision risk during specific post-operative periods. Instability or dislocation was the most common indication for revision, while infection was more frequent in constructs combining distalization and lateralization. All groups demonstrated significant improvements in EuroQol Visual Analogue Scale and Oxford Shoulder Score at 6 months. Conclusion: Humeral distalization was associated with higher medium-term revision rates despite early improvements in PROMs, highlighting trade-offs in implant selection.