Reliable designs of breast sharing based on the internal mammary perforator flap for breast reconstruction.

[BACKGROUND] Breast sharing using the contralateral breast is a reconstructive option for selected patients undergoing unilateral mastectomy who present with moderate to large ptotic breasts. The internal mammary artery perforator (IMAP) flap provides a reliable vascular basis for this approach. This study reported the authors' experience with IMAP-based breast sharing and described three surgical designs.

[METHODS] A retrospective observational case series was conducted, including 53 consecutive women who underwent unilateral breast reconstruction using an IMAP flap between January 2014 and December 2024. Eligibility criteria included age ≥40 years, moderate to large ptotic breasts, unilateral mastectomy, average contralateral oncologic risk, and completion of adjuvant oncological treatment. Preoperative planning involved computed tomography (CT) angiography and Doppler mapping for perforator selection. Three reduction mammoplasty designs (inferior, superior-medial, and superior-lateral pedicles) were employed. Outcomes included complications and patient satisfaction assessed at the final follow-up using a five-point Likert scale. An exploratory comparison of complication rates between pedicle designs was performed using Fisher's exact test.

[RESULTS] The mean patient age was 54 years, with a mean body mass index of 27. IMAPs were most frequently identified in the second to fourth intercostal spaces (ICS). Partial distal flap necrosis occurred in two patients. Total flap loss occurred in three patients and was associated with perforators arising from the fifth or sixth ICS. Major complications occurred exclusively in the inferior pedicle group (5/26 vs. 0/27; p=0.023). At the final follow-up (mean, 8 months; range, 6-12 months), no interval contralateral breast malignancies were detected. The mean (range) patient satisfaction was 4.0 (1-5).

[CONCLUSIONS] IMAP-based breast sharing is a reliable and reproducible reconstructive option in carefully selected patients. The described designs enable simultaneous reconstruction and donor-breast reshaping while preserving vascular safety and achieving balanced esthetic outcomes. The preferential selection of IMAPs from the second to fourth ICS may improve flap reliability. Larger prospective studies are required to further evaluate this approach.