Thorax anthropometric position index: a simple evaluation of the inframammary fold position in the thorax

Appropriate positioning of the inframammary fold (IMF) is essential for breast reconstruction. The purpose of this study was to quantitatively measure and evaluate the anthropometric position of the IMF in the thorax. A total of 145 Japanese women with unilateral breast cancer were analyzed. To indicate the superior-inferior position of the IMF on the non-diseased side, the distances from the sternal notch (SN) to the IMF along the midline (SN-IMFM) and from the SN to the umbilicus (UB) (SN-UB) were measured. A new index, the thorax anthropometric position (TAP) index for the IMF, was then defined as the ratio of SN-IMFM to SN-UB. The TAP index was calculated for each patient, and its correlations with demographic parameters, including age, body height, and body mass index, were statistically assessed. The TAP index was normally distributed and ranged from 0.500 to 0.704, with a mean of 0.590. Multivariate analysis revealed that age was an independent factor associated with a higher TAP index (p < .01). In addition, the paired t-test showed that the TAP index was significantly greater in the standing position than in the supine position (p < .001). The position of the IMF in the thorax could be objectively described by the TAP index, and it was suggested to become inferior with age and the standing position. The index, along with these findings, will provide useful information for the evaluation of the breast contour in an objective and simple manner.