Impact of post mastectomy radiotherapy on the silicone breast implant.

Implant based reconstruction accounts for over half of breast reconstruction performed in the UK. Patients with implant based breast reconstructions undergoing post mastectomy radiotherapy are at increased risk of capsular contracture and reconstructive failure. This study sought to determine the effect of treatment dose radiotherapy on the bulk mechanical, surface chemical properties of silicone implants as well as their cellular response. Silicone breast implant shells were submitted to treatment dose radiotherapy, 2.67 Gy (one daily fraction) and 40.05 Gy (15 fractions) using non-irradiated shells as controls. Bulk mechanical and surface chemical properties of the shells were evaluated using tensile and tear testing, attenuated total reflectance - fourier transform infrared spectroscopy (ATR-FTIR), water contact angle measurements. HDFa cells were seeded on the shells and Alamar Blue assay was performed to study cell metabolic activity. Cell morphology was evaluated using phalloidin and DAPI staining. There was no significant difference in tensile, tear strength and Young's modulus however there was reduction in maximum elongation following irradiation. Irradiation of the shells did not significant alter spectroscopy measurements nor wettability of the shells. Cell metabolism was not significantly affected by irradiation. Further analysis is warranted of the micromechanical properties to fully elucidate the effect of irradiation on the breast implant which could explain the increased rate of capsular contracture and reconstructive failure in patients undergoing post-mastectomy radiotherapy.

Mechanical and surface chemical analysis of retrieved breast implants from a single centre.

INTRODUCTION: Breast implants are associated with complications such as capsular contracture, implant rupture and leakage often necessitating further corrective surgery. Re-operation rates have been reported to occur in up to 15.4% of primary augmentation patients and up to 27% in primary reconstructions patients within the first three years (Cunningham, 2007). The aim of this study was to examine the mechanical and surface chemical properties as well as the fibroblast response of retrieved breast implants in our unit to determine the in vivo changes which occur over time. METHODS: Ethical approval was obtained. 47 implants were retrieved. Implantation time ranged from 1 month to 388 months (Mean 106.1 months). Tensile strength, elongation, Young's modulus and tear strength properties were measured using Instron 5565 tensiometer on anterior and posterior aspects of the implant. Attenuated total reflectance-fourier transform infra-red spectroscopy (ATR-FTIR), wettability and scanning electron microscopy (SEM) analysis was performed on the shell surfaces. Bicinchoninic acid assay was performed to determine shell protein content. The fibroblast response was determined by seeding HDFa cells on the retrieved implants and cell metabolism measured using Alamar Blue™ assay. RESULTS: Mechanical properties fall with increasing duration of implantation. There were no significant changes in ATR-FTIR spectra between ruptured and intact implants nor significant changes in wettability in implants grouped into 5 year categories. SEM imaging reveals surface degradation changes with increasing duration of implantation. CONCLUSIONS: With increasing duration of implantation, mechanical properties of the breast implants fall. However this was not associated with surface chemical changes as determined by ATR-FTIR and wettability nor protein content of the shells. Thus the reduction in mechanical properties is associated with breast implant failure but further research is required to elucidate the mechanisms.

Microcirculation in DIEP flaps: a study of the haemodynamics using laser Doppler flowmetry and lightguide reflectance spectrophotometry.

The deep inferior epigastric perforator (DIEP) flap is ideally suited for breast reconstruction. The DIEP flap reduces abdominal wall morbidity when compared to a transverse rectus abdominis (TRAM) flap, however, there maybe a compromise of the flap vascularity. Early venous problems and late fat necrosis in DIEP flaps can occur. There is a limited literature on the haemodynamic and microcirculation of the DIEP flap. Sixteen consecutive patients who underwent immediate breast reconstruction with DIEP flap were prospectively monitored during the post-operative time for a minimum period of 48h using laser Doppler flowmetry (LDF) and lightguide reflectance spectrophotometry (LRS) to analyse blood flow and oxygenated haemoglobin percentage in the cutaneous microcirculation of the flap. LDF demonstrated an increase of capillary flow in comparison to the pre-operative levels. LRS showed an initial decrease of the values and a varying pattern of increase in relation to time, to reach the pre-operative levels. A correlation between lower values of post-operative LDF and LRS measurements and late fat necrosis and early venous congestion was demonstrable in this series. This study demonstrates a change in the cutaneous microcirculation of the lower anterior abdominal wall following its elevation as a DIEP flap. These findings could explain the clinical phenomenon occurring in this flap in the early post-operative period. Significant correlation between longer harvesting time and re-exploration and between longer ischaemia time and localised fat necrosis was found.