Three-dimensional anthropometric evaluation of subpectoral breast augmentation using a simulation system

¹Department of Plastic and Reconstruction Surgery, Hanoi Medical University, Hanoi, Vietnam, ²Department of Plastic Reconstructive and Aesthetic Surgery, Hoe Nhai General Hospital, Hanoi, Vietnam

^&Corresponding author
Tran Bao Son, Department of Plastic Reconstructive and Aesthetic Surgery, Hoe Nhai General Hospital, Hanoi, Vietnam

Introduction    

Breast augmentation is one of the most commonly performed cosmetic surgical procedures worldwide and is consistently associated with substantial and durable improvements in body image, self-esteem, and psychosocial well-being. Large cohort studies have demonstrated significant and sustained gains in breast satisfaction and psychosocial health following augmentation, persisting several years after surgery [1]. Similar improvements in psychosocial and sexual well-being have also been reported in transfemale and male-to-female patients undergoing breast augmentation as part of gender-affirming care [2,3]. Modern augmentation techniques generally show low complication and revision rates, although rare but serious late complications highlight the importance of careful planning and long-term follow-up [4,5].

With socio-economic development and changing aesthetic expectations, the demand for implant-based breast augmentation continues to increase, including in Vietnam. Advances in implant design have introduced a wide range of volumes, shapes, projections, and surface characteristics, enabling more individualized aesthetic outcomes but also increasing the complexity of implant selection. Structured, anatomy-based planning approaches and decision-support algorithms have been shown to reduce reoperation and implant size-exchange rates by emphasizing objective tissue measurements and standardized selection processes [6,7]. Patient involvement in implant size selection further reduces dissatisfaction-driven revisions, supporting a shift toward more objective and shared decision-making models. However, while these approaches improve decision-making processes, they do not fully resolve the challenge of predicting the actual postoperative breast morphology achieved from a given implant specification. In particular, the relationship between nominal implant parameters (volume, projection, base width) and the resulting breast shape remains incompletely understood due to the influence of patient-specific soft tissue characteristics and implant-tissue interaction.

Despite these advances, conventional preoperative assessment methods, such as two-dimensional photography, external sizers, and surgeon estimation, remain limited in their ability to accurately convey postoperative breast volume, shape, and symmetry. These limitations may contribute to unmet patient expectations and revision surgery [6,7]. Three-dimensional imaging and simulation technologies have therefore been introduced to improve preoperative communication and quantitative assessment. Current evidence suggests that three-dimensional simulation enhances visualization and patient understanding; however, its role remains primarily supportive, and it has not been definitively established whether such systems can reliably quantify postoperative morphological outcomes or predict the magnitude of change in breast anthropometric parameters. Moreover, most existing studies focus on patient satisfaction or planning utility, rather than systematically quantifying early postoperative anthropometric trajectories or evaluating the discrepancy between implant specifications and achieved morphology. While prospective studies suggest that three-dimensional simulation enhances patient understanding and satisfaction with the planning process, it does not consistently outperform high-quality tissue-based planning in terms of patient-reported outcomes [8].

Recent developments in artificial intelligence have enabled simplified three-dimensional reconstruction systems based on standard clinical photographs, offering high volumetric accuracy and improved accessibility at lower cost [7,9]. These systems are increasingly viewed as complementary tools that enhance shared decision-making rather than as standalone predictors of postoperative shape. Nevertheless, there remains a critical gap in understanding how accurately these systems can capture dynamic postoperative changes and whether they can provide objective, reproducible measurements that reflect real surgical outcomes, particularly in the early postoperative period. In addition, limited data are available regarding the extent to which achieved breast volume and projection correspond to nominal implant dimensions under subpectoral placement, where muscular coverage may alter final morphology. Therefore, the present study was designed not to validate the simulation system itself, but to use three-dimensional anthropometric analysis as a quantitative tool to address two unresolved questions: (1) how breast anthropometric parameters evolve in the early postoperative period following subpectoral augmentation, and (2) how implant characteristics relate to the actual achieved breast volume and projection. We hypothesized that (i) postoperative breast morphology would demonstrate an early increase followed by partial stabilization, and (ii) the effective gains in breast volume and projection would be consistently lower than nominal implant specifications due to implant-tissue interaction. The present study aimed to evaluate preoperative breast anthropometry and postoperative morphological changes following subpectoral breast augmentation using a three-dimensional simulation system, to provide objective data to support implant selection and surgical planning.

Methods     

Study design: this prospective, single-arm observational study evaluated anthropometric changes following primary breast augmentation with silicone implants.

Setting: the study was conducted at Hoe Nhai Hospital between May 2024 and September 2024. All surgical procedures and follow-up assessments were performed by the same aesthetic surgery team using standardized operative and evaluation protocols.

Participants: the study population comprised women undergoing primary breast augmentation with silicone implants during the study period. Eligible participants underwent isolated implant-based augmentation without concomitant breast procedures such as mastopexy, fat grafting, areolar reduction, or other adjunctive surgery. In all cases, implants were placed in the subpectoral plane. Patients were excluded if they declined participation or consent for three-dimensional photographic analysis, failed to attend scheduled follow-up visits, or had chest wall deformities such as pectus excavatum or spinal deformity. A total of 27 patients (54 breasts) met eligibility criteria and were included. Participants were recruited consecutively during the study period, representing a convenience sample of all eligible cases presenting to the study center rather than a randomly selected population.

Variables: patient-related variables included age, height, body weight, and body mass index. Breast anthropometric variables included unilateral breast volume, sternal notch-to-nipple distance, inter-nipple distance, nipple-to-inframammary fold distance, breast projection, breast width, intermammary distance, and areolar diameter. Implant-related variables included implant volume, base width, and projection. Outcomes comprised postoperative changes in breast anthropometry at 14 days and 1 month and their association with implant characteristics.

Data sources/measurement: clinical and operative data were recorded in a standardized aesthetic surgery medical record. Patients were assessed preoperatively, at 14 days, and at 1 month postoperatively. At each time point standardized breast photographs were obtained in frontal, right oblique, and left oblique views with patients standing upright in a neutral posture during relaxed expiration. Inter-nipple distance was measured directly. Images and measurements were uploaded to the Crisalix three-dimensional simulation system, which reconstructed breast models and automatically calculated unilateral breast volume and other anthropometric parameters using predefined anatomical landmarks.

Bias: measurement bias was minimized through standardized photographic acquisition, consistent patient positioning, predefined anatomical landmarks, and automated three-dimensional software analysis. Procedural variability was limited because all surgeries were performed by the same team using a uniform subpectoral technique. However, the use of a convenience sampling strategy over a limited time frame may introduce selection bias, as the study population may not be fully representative of the broader population of patients undergoing breast augmentation, particularly with respect to patient preferences, anatomical characteristics, or socioeconomic factors. Additionally, patients treated at a single specialized center may differ systematically from those in other clinical settings. These factors may limit the external validity and generalizability of the findings.

Study size: the sample size comprised all eligible patients undergoing primary implant-based breast augmentation during the study period, resulting in 27 participants (54 breasts) without prior sample size calculation. No formal sample size estimation was performed, as the study was exploratory in nature and intended to include all consecutive eligible cases within the predefined study period.

Quantitative variables: continuous variables, including anthropometric measurements and implant dimensions, were summarized as means with standard deviations. Breast measurements were evaluated longitudinally at three predefined time points (preoperative, 14 days postoperative, and 1 month postoperative). Implant characteristics were analyzed as continuous predictors of postoperative anthropometric change.

Statistical methods: data were entered and analyzed using Microsoft Excel and SPSS software. Continuous variables were summarized as mean ± standard deviation and categorical variables as frequencies and percentages. Paired comparisons of anthropometric measurements across time points (preoperative vs. 2 weeks, and 2 weeks vs. 1 month) were performed using paired t tests. Comparisons between independent groups (e.g., implant surface types) were conducted using independent samples t tests. Exploratory associations between patient characteristics and breast volume were assessed using correlation analysis rather than multivariable regression, given the limited sample size. For all continuous variables, 95% confidence intervals (95% CI) were calculated to provide an estimate of precision. Results are presented as mean ± standard deviation with corresponding 95% CI where appropriate. A two-sided p value < 0.05 was considered statistically significant.

Ethical consideration statement: all participants provided written informed consent for study participation and use of clinical images for three-dimensional analysis. Patient confidentiality was strictly maintained. The study was conducted in accordance with ethical principles for research involving human subjects and institutional regulations governing clinical research.

Results     

Demographic characteristics: a total of 27 female patients were included in the study, corresponding to 54 breasts. All patients underwent primary breast augmentation with subpectoral implant placement. The mean age at surgery was 34.63 ± 6.46 years (range: 21-50 years). Baseline anthropometric characteristics and their relationships with native breast volume are summarized in Table 1. Mean body weight was 51.0 ± 5.32kg, mean height was 158.04 ± 4.81cm, and mean body mass index was 20.38 ± 1.53kg/m². The mean preoperative breast volume was 169.17 ± 70.06cc. Linear regression analysis demonstrated a significant positive correlation between body weight and breast volume (p = 0.03). In contrast, breast volume was not significantly associated with height (p = 0.10) or body mass index (p = 0.08), indicating that breast volume was primarily related to body weight rather than overall body habitus.

Preoperative breast anthropometry and asymmetry: preoperative breast anthropometric parameters for the right and left breasts are presented in Table 2. Mean breast volume was 165.85 ± 69.3cc on the right side and 172.48 ± 71.9cc on the left side. Mean sternal notch-to-nipple distance was 18.04 ± 1.38cm on the right and 18.02 ± 1.25cm on the left. Other parameters, including nipple-to-inframammary fold distance, breast projection, and breast width, showed small side-to-side differences. Although asymmetry was observed across all anthropometric parameters, none of the differences between the right and left breasts reached statistical significance (all p > 0.05). The mean absolute inter-breast volume difference was 20.56 ± 17.02cc. A clinically relevant asymmetry greater than 25cc (equivalent to approximately one implant size difference) was observed in 30% of patients.

Implant characteristics and selection patterns: the characteristics of the implants used are summarized in Table 3. The mean implant volume was 300.28cc, with a mean projection of 3.98cm and a mean base width of 11.51cm, representing a moderate implant profile. Analysis of implant surface type by volume group showed that smooth implants were predominantly used in the larger-volume group (>285cc), accounting for 25 of 38 implants, whereas microtextured implants were more frequently used in the smaller-volume group (≤285cc), accounting for 11 of 16 implants. When stratified by implant type, patients receiving microtextured implants had significantly larger native breast volumes compared with those receiving smooth implants (198.46cc vs. 145.73cc, p = 0.0049), as shown in Table 4. Overall, implant size asymmetry between the two breasts was applied in 33.3% of patients to correct preoperative volume differences.

Postoperative changes in breast anthropometry: changes in breast anthropometric parameters over time are summarized in Table 5. Comparison between preoperative values and measurements at 2 weeks postoperatively showed statistically significant changes in all parameters except inter-nipple distance. Significant increases were observed in sternal notch-to-nipple distance, nipple-to-inframammary fold distance, breast projection, breast width, and breast volume. In contrast, intermammary distance significantly decreased from 2.82 ± 0.31cm to 2.35 ± 0.39cm. Between 2 weeks and 1 month postoperatively, only breast projection showed a statistically significant reduction (from 9.06 ± 0.82cm to 8.65 ± 0.86cm). All other parameters remained stable, with no significant differences.

Relative contribution of implants to breast volume and projection: the mean percentage increase in breast volume relative to implant volume was 84.0% ± 23.7% at 2 weeks postoperatively and decreased to 74.5% ± 23.0% at 1 month, with a statistically significant difference (p = 0.036). Similarly, the mean percentage increase in breast projection relative to implant projection was 62.8% ± 15.7% at 2 weeks and decreased to 51.9% ± 19.7% at 1 month (p = 0.002), indicating partial reduction over time as postoperative swelling subsided.

Discussion     

This prospective study demonstrates that three-dimensional anthropometric analysis provides objective, quantitative insight into breast morphology before and after subpectoral breast augmentation. The findings show that native breast volume is primarily associated with body weight rather than overall body habitus, that clinically relevant preoperative asymmetry is common and frequently requires asymmetric implant sizing, and that postoperative breast shape changes are characterized by early global enlargement followed by partial stabilization. Importantly, the effective gains in breast volume and projection were consistently lower than the nominal implant dimensions, underscoring the role of implant-tissue interaction and subpectoral placement in determining final breast morphology. These findings should be interpreted primarily as descriptive of early postoperative morphological changes rather than as evidence of improved clinical decision-making or outcomes.

In this cohort, the mean preoperative breast volume was 169.17 ± 70.06cc, indicating that most patients presented with relatively small native breast volumes. However, the observed range (43-343cc) shows substantial heterogeneity, and a proportion of patients had volumes approaching values reported in broader populations. This reinforces the concept that the indication for aesthetic breast augmentation is not determined solely by objective volume deficiency but also by patient-specific aesthetic expectations and body image perception. A similar phenomenon has been described in reconstructive settings, where larger initial breast volumes are associated with greater absolute postoperative volume changes over time, yet patient satisfaction remains influenced by relative rather than absolute volume retention [10].

Preoperative linear measurements in our study demonstrated relatively small absolute values, particularly for sternal notch-to-nipple and nipple-to-inframammary fold distances, consistent with limited lower-pole development. Specifically, the nipple-to-inframammary fold distance (5.18 ± 0.81cm) was shorter than the 6.8cm reported by Qiao et al. [11], reflecting the underdeveloped lower pole and relatively high inframammary fold typically observed in small or hypoplastic breasts. In contrast, mean breast projection in our study (6.56 ± 0.97cm) exceeded values reported by Qiao et al. [11] and Kim et al. [12], a discrepancy that is likely attributable to methodological differences, as our three-dimensional system measured projection to the nipple apex, whereas previous studies did not include nipple height in projection measurements. Postoperatively, we observed significant early increases in these dimensions, especially in nipple-to-inframammary fold distance, while breast width increased only modestly and stabilized thereafter. This pattern aligns with endoscopic transaxillary augmentation data showing preferential elongation of the lower pole (NF +2.3cm, +42.6%) with minimal change in base diameter (+0.4cm, +3.2%) at 1 year [13]. Large multicenter analyses of aesthetic breast surgery have similarly demonstrated that changes in standard linear measurements such as SN-nipple and SN-IMF follow highly consistent trajectories across procedure types, supporting their use in predictive planning [14].

Although mean right-left differences in breast volume and linear dimensions were not statistically significant at the group level, clinically relevant asymmetry was common, with 30% of patients exhibiting inter-breast volume differences greater than 25cc. This observation is consistent with three-dimensional volumetric studies showing that while mean right-left differences may not reach statistical significance in upright measurements, individual absolute asymmetries are frequent and clinically meaningful [15]. Importantly, volumetric asymmetry assessment is sensitive to patient position: supine measurements can differ from standing measurements by more than 120cc, whereas sitting and standing measurements differ minimally [15].

Implant selection in this study was closely aligned with native breast morphology, as reflected by the significant difference in preoperative breast volume between patients receiving smooth versus microtextured implants. This individualized approach is consistent with structured, measurement-based algorithms that emphasize base diameter as a primary constraint and actively involve patients in implant size selection. However, it should be emphasized that the present study does not directly evaluate clinical outcomes such as patient satisfaction, decision-making accuracy, or revision rates, and therefore cannot establish the effectiveness of such approaches in improving these outcomes.

Postoperative volumetric and projection changes

Postoperatively, breast volume increased markedly at 2 weeks and partially regressed by 1 month, with relative volume gains of 84.0% and 74.5% of implant volume, respectively. This early overshoot, followed by stabilization mirrors volumetric behavior reported in both implant-based and autologous breast reconstruction. In free-flap reconstructions, mean breast volume decreases by approximately 11% over the first 6 months, with larger initial volumes associated with greater absolute loss [10]. Conversely, oncoplastic volume replacement using acellular dermal matrix demonstrates high long-term stability, with only 4.3-4.5% volume loss at 24 months despite frequent adjuvant radiotherapy [16]. In our implant-based cohort, the reduced effective contribution of implant volume and projection, particularly under subpectoral placement, likely reflects a combination of postoperative edema resolution, tissue elasticity, muscular compression, and implant deformation. The accompanying increase in projection followed by partial regression is consistent with preferential lower-pole expansion and anterior translation rather than sustained maximal projection, as reported in longitudinal augmentation studies [13].

From a clinical perspective, these findings provide quantitative insight into early postoperative morphological changes and may support more informed interpretation of surgical outcomes. However, their application to implant selection or prediction of long-term results should be considered exploratory and hypothesis-generating rather than definitive.

Several limitations should be acknowledged. The study included a relatively small sample size from a single center, which may limit generalizability. Follow-up was restricted to the early postoperative period, precluding assessment of long-term morphological stability. All implants were placed in the subpectoral plane, and results may differ with alternative techniques. In addition, the analysis treated each breast as an independent observation, which may introduce bias due to the non-independence of bilateral data within the same patient. Measurement error is also possible, as three-dimensional reconstruction relies on software-based modeling that may be influenced by image quality, patient positioning, and algorithmic assumptions. Furthermore, early postoperative measurements may be affected by transient swelling and tissue edema, which could confound the interpretation of changes in breast volume and projection. These factors represent potential threats to internal validity and should be considered when interpreting the results. Future studies with larger cohorts, longer follow-up, and comparative implant placement strategies are warranted to further refine the clinical utility of three-dimensional breast anthropometry.

Conclusion     

Three-dimensional anthropometric analysis allows objective assessment of breast morphology before and after subpectoral breast augmentation. Although surgery produced significant improvements in breast volume, projection, and overall contour, the effective volumetric and projection gains were consistently lower than the nominal implant dimensions due to tissue biomechanics and implant-tissue interaction. These findings describe short-term postoperative morphological changes and highlight the complexity of predicting the achieved breast shape based on implant specifications alone. While the results may inform understanding of early postoperative outcomes, further studies incorporating long-term follow-up and patient-centered outcomes are required before making clinical decisions or optimizing implant selection.

Competing interests     

The authors declare no competing interests.

Authors' contributions     

Nguyen Minh Nghia: study conception and design, data acquisition, three-dimensional analysis, and manuscript drafting. Tran Bao Son: study supervision, surgical procedures, methodological guidance, and critical revision of the manuscript. Vo Thao Trinh: data collection and photographic standardization. Nguyen Minh Hien: clinical data management and follow-up assessment. Pham The Hien: statistical analysis and interpretation of results. Nguyen Van Thai: literature review and manuscript editing. Do Quang Phuc: methodological support and data validation. All authors read and approved the final manuscript.

Acknowledgments     

The authors thank the staff of the Department of Plastic Reconstructive and Aesthetic Surgery, Hoe Nhai General Hospital, for their assistance in patient care, clinical photography, and data collection.

Tables     

Table 1: association between patient anthropometric characteristics and breast volume

Table 2: preoperative breast anthropometric measurements by side

Table 3: implant characteristics

Table 4: native breast volume by implant surface type

Table 5: changes in breast anthropometric parameters over time

References