# Influence of Arthroplasty Type, Comorbidities, and Fracture Status on Outcomes After Shoulder Replacement: Analysis of 664,545 Cases

## TL;DR

This study analyzes how different types of shoulder replacement surgeries and patient conditions affect hospital stays and complications in over 664,545 cases.

## Contribution

The study identifies independent effects of surgery type, comorbidities, and fracture status on postoperative outcomes in shoulder arthroplasty.

## Key findings

- Reverse total shoulder arthroplasty (RTSA) increases hospitalization and complication risks compared to anatomic total shoulder arthroplasty (ATSA).
- Proximal humerus fractures (PHFs) independently worsen length of stay, mortality, and complication risks after shoulder replacement.
- Hemiarthroplasty (HA) has the highest complication and hospitalization risks among the three surgical types.

## Abstract

Background: Shoulder arthroplasty is performed for various etiologies, including osteoarthritis, proximal humerus fractures (PHFs), and rotator cuff tears. While previous studies have focused on outcomes based on implant choice, less is known about the independent effects of surgery type, comorbidities, and fracture status on postoperative outcomes. This study evaluates their influence on length of stay (LOS), in-hospital mortality, and postoperative complications. Methods: A retrospective cohort analysis of 664,545 patients undergoing anatomic total shoulder arthroplasty (ATSA), reverse total shoulder arthroplasty (RTSA), or hemiarthroplasty (HA) was conducted. Multivariable Poisson and logistic regression models assessed predictors of LOS, mortality, and complications. Results: Among 132,909 patients, 63.3% underwent RTSA, 31.3% underwent ATSA, and 5.4% underwent HA. Mean hospitalization was longest for HA (2.56 days) and RTSA (1.82 days) compared to ATSA (1.39 days; p < 0.001). Poisson regression confirmed that RTSA increased LOS by 24.1% versus ATSA (IRR = 1.24, p < 0.001), while HA had the highest LOS (IRR = 1.58, p < 0.001). Postoperative complications were observed in 8.37% of ATSA, 13.81% of RTSA, and 17.81% of HA cases (overall ~12.3%). Compared with ATSA, RTSA increased the odds of complications (OR = 1.48, p < 0.001), while HA presented the greatest complication risk (OR = 1.51, p < 0.001). Among proximal humerus fracture (PHF) patients (9.9% of the cohort), 84.7% underwent RTSA. PHF independently increased LOS (IRR = 1.61, p < 0.001), mortality (OR = 1.62, p = 0.051), and complications (OR = 2.33, p < 0.001). Conclusions: RTSA is associated with longer hospitalization and higher complication rates, while PHF worsens LOS, mortality, and complication risk.