Long-Term Ultrasonographic and Histologic Changes in Acellular Dermal Matrix in Implant-Based Breast Reconstructions

BACKGROUND: Acellular dermal matrix (ADM) is composed of extracellular matrix (ECM) and is widely used in implant-based breast reconstructions. However, long-term changes in the ADM around implants have not been established. This study aimed to investigate long-term changes in the ADM covering breast implants using serial ultrasound and histologic evaluations. METHODS: The authors evaluated the ultrasound results of 145 patients who underwent implant-based breast reconstructions with ADM coverings. The ultrasound results obtained within 18 months of surgery and those obtained 5 years postoperatively were analyzed to determine the change in ADM thickness. For histologic analysis, the ADM was harvested from 30 patients who underwent secondary breast surgery. Histologic features of the ECM and cellular components within the ADM were compared at specific intervals from ADM implantation and the second operation (early ADM group, <18 months; late ADM group, >5 years postoperatively). RESULTS: The ADM thickness on ultrasound examination was significantly decreased in the late ADM group compared with that in the early ADM group ( P < 0.001). Histologic analyses revealed that the late ADM group had less thickness with lower ECM levels versus the early ADM group. Increased infiltration of host cells, such as vascular endothelial cells, myofibroblasts, and immune cells, occurred in the late ADM group. CONCLUSIONS: Implanted ADMs underwent gradual thinning over time, in addition to ECM reduction and infiltration of host cells. These findings are useful in understanding the natural course of ADMs currently used in implant-based breast reconstructions. CLINICAL QUESTION/LEVEL OF EVIDENCE: Therapeutic, V.