A Predictive Model for Determining Permanent Implant Size During 2-Stage Implant Breast Reconstruction

Predicting Final Implant Volume in Two-stage Prepectoral Breast Reconstruction

Two-stage implant-based breast reconstruction remains the most commonly performed reconstructive modality following mastectomy. Although prior studies have explored the relationship between tissue expander (TE) features and permanent implant (PI) size in subpectoral reconstruction, no such study exists in prepectoral reconstruction. This study aims to identify pertinent TE characteristics and evaluate their correlations with PI size for prepectoral implant-based reconstruction.

METHODS

This study analyzed patients who underwent two-stage prepectoral tissue expansion for breast reconstruction followed by implant placement. Patient demographics and oncologic characteristics were recorded. TE and PI features were evaluated. Significant predictors for PI volume were identified using linear and multivariate regression analyses.

RESULTS

We identified 177 patients and 296 breast reconstructions that met inclusion criteria. All reconstructions were performed in the prepectoral plane with the majority using acellular dermal matrix (93.8%) and primarily silicone implants (94.3%). Mean TE size was 485.4 cm³ with mean initial fill of 245.8 cm³ and mean final fill of 454.4 cm³. Mean PI size was 502.9 cm³ with a differential fill volume (PI-TE) of 11.7 cm³. Multivariate analysis identified significant features for PI size prediction, including TE size (R² = 0.60; P < 0.0001) and TE final fill volume (R² = 0.57; P < 0.0001). The prediction expression for TE final fill and TE size was calculated as 26.6 + 0.38*(TE final fill) + 0.61*(TE size).

CONCLUSIONS

TE size and final expansion volume were significant variables for implant size prediction. With prepectoral implant placement gaining popularity, the predictive formula may help optimize preoperative planning and decision-making in prepectoral reconstructions.

Elastic net of polyurethane strands for sustained delivery of triamcinolone around silicone implants of various sizes

We propose an elastic net made of a biocompatible polymer to wrap silicone implants of various sizes, which also allows for the sustained release of an anti-inflammatory drug, triamcinolone, to prevent fibrosis. For this, we first prepared a strand composed of a mixture of polyurethane and triamcinolone via electrospinning, which was then assembled to prepare the elastic drug-delivery net (DDN). The DDN was prepared to just fit for wrapping the small silicone implant sample herein, but was also able to wrap a sample 7 times as large at 72% strain due to the elastic property of polyurethane. The DDN exhibited sustained drug release for 4 weeks, the profile of which was not very different between the intact and strained DDNs. When implanted in a subcutaneous pocket in living rats, the DDN-wrapped silicone implant samples showed an obvious antifibrotic effect due to the sustained release of triamcinolone. Importantly, this effect was similar for the small and large silicone samples, both wrapped with the same DDN. Therefore, we conclude that this drug-loaded net made of an elastic, biocompatible polymer has high potential for sustained drug delivery around silicone implants manufactured in various sizes.

3D Printing Breast Tissue Models: A Review of Past Work and Directions for Future Work

Breast cancer often results in the removal of the breast, creating a need for replacement tissue. Tissue engineering offers the promise of generating such replacements by combining cells with biomaterial scaffolds and serves as an attractive potential alternative to current surgical repair methods. Such engineered tissues can also serve as important tools for drug screening and provide in vitro models for analysis. 3D bioprinting serves as an exciting technology with significant implications and applications in the field of tissue engineering. Here we review the work that has been undertaken in hopes of generating the recognized in-demand replacement breast tissue using different types of bioprinting. We then offer suggestions for future work needed to advance this field for both in vitro and in vivo applications.