Anatomy and tensile strength of the abdominal head of the pectoralis major muscle in relation to transaxillary breast augmentation

Background This study aimed to elucidate the anatomy of the abdominal head of the pectoralis major (AHPM) in relation to transaxillary breast augmentation (TBA). Methods In 20 hemithoraxes of fresh Korean cadavers, the width, thickness, and location of the origin of the AHPM were measured in relation to the seventh rib-costal cartilage junction. A force gauge was used to measure the force needed to detach the AHPM from its origin. In another four breasts, an implant pocket was made first, followed by observation of the AHPM. In 92 patients who underwent surgery, the AHPM was observed at its origin during performance of endoscopic TBA. Results The AHPM was observed in 23 (96 %) of 24 hemithoraxes dissected. The AHPM was observed in 170 (92.4 %) of 184 breasts subjected to surgery. The AHPM originated from the rectus fascia at the sixth (60 %) and seventh (35 %) costochondral junctions. The width of the AHPM was 23.5 ± 5.2 mm at its origin, 15.2 ± 3.9 mm at midbelly, and 7.3 ± 4.3 mm at insertion. The thickness of the AHPM at its origin was 1.6 ± 0.5 mm. The force needed to detach AHPM from its origin was 23.5 ± 12.0 N. In two cadavers of mock surgery, the AHPM could limit the boundary of the implant pocket after division of the costal origins. After division of the AHPM, the free inferior space was obtained. Conclusion In submuscular or dual-plane breast augmentation, the AHPM should be cut to place the implant in the correct desired position. Level of Evidence III This journal requires that authors assign a level of evidence to each article. For a full description of these Evidence-Based Medicine ratings, please refer to the Table of Contents or the online Instructions to Authors www.springer.com/00266.