Timing of Acellular Dermal Matrix Placement in Two-stage Breast Reconstruction: Effects on Contracture and Complications.

[BACKGROUND] Acellular dermal matrix (ADM) is commonly used in implant-based breast reconstruction, but the optimal timing of ADM use in prepectoral two-stage reconstruction remains uncertain.

[OBJECTIVES] We evaluated whether delaying ADM application to the second-stage implant exchange (after initial tissue expansion without ADM) decreases meaningful capsular contracture without increasing reconstructive failure.

[METHODS] We performed a retrospective cohort study of adult women undergoing immediate, prepectoral two-stage tissue expander reconstruction at a single institution. Patients were stratified by ADM timing: ADM placed at first-stage expander insertion versus delayed ADM applied at second-stage implant exchange with full implant wrapping. The primary outcome was tissue expander loss. Secondary outcomes included seroma, hematoma, infection, and capsular contracture graded by the Baker scale. Multivariable logistic regression adjusted for covariates, including body mass index, mastectomy weight, chemotherapy, and cancer stage.

[RESULTS] Tissue expander loss did not differ between groups. Overall early postoperative complication patterns were similar; however, delayed ADM use was associated with more seroma events among patients who received postmastectomy radiotherapy and/or underwent axillary lymph node dissection. After definitive implant placement, delayed ADM application was associated with a lower incidence of clinically significant capsular contracture (Baker grade III/IV: 4.4% vs 25.0%, P = 0.014) compared with ADM placement at the first stage, and this association persisted after covariate adjustment (adjusted OR 0.13, 95% CI 0.02-0.89; P = 0.038).

[CONCLUSIONS] In prepectoral two-stage reconstruction, deferring ADM to the implant-exchange stage may reduce capsular contracture without increasing expander loss. Because seroma risk may be higher in patients receiving radiotherapy and/or axillary surgery, ADM timing should be individualized and paired with seroma-mitigation strategies in higher-risk patients.