METHODS

All patients undergoing NSM reconstruction at Mayo Clinic Florida from January 2020 to May 2023 were assessed. The vertical and horizontal axial proportions associated with NAC location on the breast were calculated using pixel measurements taken from standardized pre-operative and post-operative clinical photographs. Both frontal and lateral views of the patient were considered, with measurements being taken for the frontal view of horizontal axis NAC location and both frontal and lateral views of vertical axis NAC location [Figure 2].

The pre-operative and post-operative NAC position calculated ratios were then respectively compared to those considered "ideal" in existing survey research⁴. According to this research on NAC location and proportions, "ideal" positioning would be:

• 40:60alongthehorizontalx-axisinfrontalview

• 50:50alongtheverticalx-axisinbothfrontalandlateralviews.

Various patient and surgical technique demographics were collected. Variables that could affect NAC malposition (i.e., incision type, plane of placement, acellular dermal matrix (ADM) usage, and type of reconstruction) were analyzed using a linear mixed effects regression model to account for the additional variation in NAC position by these variables. Both univariate models and multivariate models were utilized.

All statistical tests were two-sided. Statistical analyses were performed using R Statistical Software (version 4.1.2; R Foundation for Statistical Computing, Vienna, Austria).

RESULTS

A total of 88 NSM reconstruction patients were assessed. 6 patients were excluded for missing data (e.g., no post-operative photos). The remaining 82 NSM reconstruction patients were included for analysis. Patient demographic information is outlined in [Figure 1]. Patients tended to be middle-aged (mean approximately age 50), the majority had: bilateral mastectomy (82.9%), incision location at the inframammary fold (IMF) (64%), subpectoral implant/tissue expander (TE) placement (67.1%), ADM usage (53.7%), and were staged TE reconstruction type (62.2%).

NAC malposition (in reference to the ideal), was more post-operatively than pre-operatively in both frontal and lateral views of the vertical axis [Table 1]. For both the pre-operative and post-operative groups, the NAC positionings tended to be more inferior and more lateral from midline from the frontal view [Table 1].

From the lateral view, vertical ratios in comparison to ideal ratios, there was a statistically significant effect to NAC position by the variables: time (pre-operative and post-operative) (p=0.013, p=0.013), incision type (p=0.003, p = 0.007), and ADM use (p<0.001, p=0.033), in both univariate and multivariate analysis, respectively [Table 2]. Plane of placement (pre-pectoral vs. sub-pectoral) (p=0.012, p=0.70 ) and reconstruction type (TE vs. DTI) (p=0.058, p=0.87), had a statistically significant effect to NAC position only in the univariate model but not after controlling for the other variables in the multivariate model, respectively [Table 2]

From the frontal view, vertical ratios in comparison to ideal ratios, there was a statistically significant effect to NAC position by the variables: time (pre-operative and post-operative) (p=0.006, p=0.006) and ADM use (p<0.001, p=0.025), in both univariate
and multivariate analysis, respectively [Table 3]. Plane of placement (pre-pectoral vs. sub-pectoral) (p=0.011, p=0.81) and reconstruction type (TE vs. DTI) (p=0.029, p=0.59), had a statistically significant effect to NAC position only in the univariate model but not after controlling for the other variables in the multivariate model, respectively [Table 3] .

From the frontal view, horizontal ratios in comparison to ideal, none of the variables had a statistically significant effect to NAC position.

DISCUSSION

The greater NAC malposition seen post-operatively in nipple-sparing mastectomy reconstruction patients may also be associated with the use of a smooth, round implant or anatomic shaped tissue expander to reconstruct a natural tear-dropped anatomic shaped breast that has a footprint that is a larger surface area than the implant or tissue expander.

Due to the retrospective design of this study, there was some inconsistency in the timing of post-operative photographs and measurements. Thus, another potential contributing factor to NAC malposition may be affected from the time that has elapsed from surgery to clinical photographs. For example, the NAC position may be in a more optimal position and closer to ideal in patients who have had more time since surgery for their tissue to heal and undergo relaxation.