Both Bilateral Breast Volume Discrepancy and Asymmetric Anterior Chest Wall Shape Contribute to the Unsightly Breast Contour in Female Right Thoracic Idiopathic Scoliosis.

Abstract

A retrospective radiographic study. To evaluate the asymmetry of breast volume (BV) and shape in female adolescent idiopathic scoliosis (AIS) patients and to define their relationship with deformed components of the anterior chest wall and curved spine. The higher incidence of asymmetric breast development in AIS was described by prior studies. However, the interplay between scoliosis curve magnitude and severity of breast asymmetry (BA) are unknown. A total of 73 surgically treated female right thoracic AIS patients classified as Lenke type I were enrolled in this study, with the average Cobb angle being 52.08±11.68 degrees. The Image J software was utilized to calculate BV. Both concave and convex radiographic parameters of breast shape were measured including the extraversion angle (EA), the coverage angle (CA), the axial breast height, the vertical breast height (VBH), and the nipple-to-sternum distance. The inclination angles of the concave and convex anterior chest wall were also assessed. BA was calculated according to the formula as follows: BA=(concave-convex)×BV/[(concave+convex)×BV]/2. The measurements of spinal deformity parameters included the Cobb angle, the RAsag angle, and the RAml angle. Paired t test was performed to analyze the asymmetry of breast shape, and Pearson correlation analysis was utilized to define the correlation between the breast shape, spinal deformity, and the inclination of anterior chest wall. The concave BV, EA, axial breast height, and vertical breast height were significantly larger than those of the convex side (P<0.05), whereas the concave CA and the inclination angle of the anterior chest wall were significantly smaller than those of the convex side (P<0.05). No difference was detected between the concave and the convex nipple-to-sternum distance (P>0.05). The averaged BA was 11.4%, with the ratio of asymmetry beyond 10% being 52.1%. No statistically significant relationships between BA and Cobb angle, RAsag angle, RAml angle were detected (P>0.05). The inclination angle of the anterior chest wall demonstrated significant correlation with EA (P<0.001) and CA (P<0.001), respectively. The incidence of BA in AIS is notable, with the concave breast being larger, more extroversive, and more concentrated than the convex breast. The discrepancy between concave and convex anterior chest wall inclination bound to scoliosis could have a major influence on breast orientation and profile, suggesting a synergistic role of anterior chest wall deformity and bilateral BV discrepancy in the formation of BA.