Comparison of functional outcomes between medialized and lateralized reverse shoulder prostheses in acute proximal humerus fractures

HYPOTHESIS/BACKGROUND: Reverse shoulder arthroplasty (RSA) is increasingly used for complex proximal humerus fractures (PHFs). Although lateralized designs have demonstrated advantages in elective indications, their role in acute PHFs remains uncertain. This study evaluated functional outcomes following RSA for acute PHFs, with particular focus on the influence of greater tuberosity (GT) healing and prosthesis design. METHODS: In this multicenter retrospective study, 122 patients with acute PHFs treated with RSA and a minimum follow-up of two years were included. Two centers used lateralized designs, and two centers used medialized designs. Functional outcomes (Constant score) and rates of GT healing, scapular notching, dislocation, infection, and revision surgery were recorded. Welch's and two-proportion z tests compared groups, and multivariate regression identified independent predictors. RESULTS: The mean Constant score at the 2-year follow-up was 57.9 ± 14.1 points, with no significant differences between the medialized (58.4 ± 11.6) and lateralized models (57.4 ± 16.7). No statistically significant differences were observed in GT healing, scapular notching, dislocation, infection or revision surgery between designs. Overall, the GT healed in 65% of patients, and scapular notching was reported in 24.6%. There were significant differences in the Constant score between patients with (61.6 ± 12.3) and without (51.2 ± 14.9) GT healing (p < 0.001) and patients with (52.2 ± 15.5) and without (59.8 ± 13.2) scapular notching (p = 0.010). GT healing was the only independent predictor of higher Constant scores. CONCLUSIONS: Greater tuberosity healing was the only independent predictor of functional outcome. Differences between prosthesis designs were not significant and should be interpreted in the context of center-specific treatment strategies.