25. Infection Risk and Patient-reported Outcomes Show Inverse Associations Across Complete Submuscular, Partial Submuscular, and Prepectoral Tissue Expander Placement

PURPOSE: Tissue expanders can be placed in complete submuscular, partial submuscular, or prepectoral planes. Comparative studies assessing the relationship between plane placement, infection risk, and patient-reported outcomes (PROs) remain limited. We hypothesized that the risk of infection and PROs vary inversely with the amount of muscle that covers the expander. METHODS: Retrospective analysis of patients who underwent immediate breast reconstruction with expander placement between 2017-2023. Patients were grouped as complete submuscular, partial submuscular with acellular dermal matrix sling, and prepectoral. Postoperative complications and BREAST-Q Physical Well-Being of the Chest (PWBC) were evaluated before second-stage reconstruction. RESULTS: 3,707 patients were included. Prepectoral placement had a higher incidence of surgical site infection (9.1%) compared to complete submuscular (3.1%) and partial submuscular (7.1%) placement (p<0.001). Prepectoral reconstruction was associated with increased odds of infection (OR 3.38, 95% CI: 2.44-4.75; p<0.001) compared to complete submuscular. However, prepectoral patients had higher PWBC scores (median, 76) than complete and partial submuscular patients (median, 72). Prepectoral (β=3, 95% CI: 2.0-4.1; p<0.001) and partial submuscular (β=1.6, 95% CI: 0.1-3.1; p=0.037) were associated with higher PWBC scores at six months compared to complete submuscular. CONCLUSION: With decreasing muscle coverage, patients reconstructed with tissue expanders were more likely to develop infection and less likely to have unfavorable PWBC scores. The choice of tissue expander plane should balance risk of infection with PROs.