gms | German Medical Science

45. Jahrestagung der Deutschen Gesellschaft der Plastischen, Rekonstruktiven und Ästhetischen Chirurgen (DGPRÄC), 19. Jahrestagung der Vereinigung der Deutschen Ästhetisch-Plastischen Chirurgen (VDÄPC), 52. Jahrestagung der Österreichischen Gesellschaft für Plastische, Ästhetische und Rekonstruktive Chirurgie (ÖGPÄRC)

11.09. - 13.09.2014, München

In vivo evaluation of newly modified breast implant surfaces in a Minipig-Model

Meeting Abstract

  • presenting/speaker Inesa Sukhova - München, Deutschland
  • Mohit Chhaya - Queensland University of Technology , Institute of Health and Biomedical Innovation, Brisbane, Australia
  • Dietmar Hutmacher - Klinikum rechts der Isar der Technischen Universität München, Klinik für Plastische Chirurgie und Handchirurgie, München, Deutschland
  • Daniel Mueller - Klinikum rechts der Isar, Technische Universität München, Plastische Chirurgie und Handchirurgie, München, Deutschland
  • Hans-Günther Machens - München, Deutschland
  • Jan-Thorsten Schantz - München, Deutschland

Deutsche Gesellschaft der Plastischen, Rekonstruktiven und Ästhetischen Chirurgen. Vereinigung der Deutschen Ästhetisch-Plastischen Chirurgen. Österreichische Gesellschaft für Plastische, Ästhetische und Rekonstruktive Chirurgie. 45. Jahrestagung der Deutschen Gesellschaft der Plastischen, Rekonstruktiven und Ästhetischen Chirurgen (DGPRÄC), 19. Jahrestagung der Vereinigung der Deutschen Ästhetisch-Plastischen Chirurgen (VDÄPC), 52. Jahrestagung der Österreichischen Gesellschaft für Plastische, Ästhetische und Rekonstruktive Chirurgie (ÖGPRÄC). München, 11.-13.09.2014. Düsseldorf: German Medical Science GMS Publishing House; 2014. Doc264

doi: 10.3205/14dgpraec121, urn:nbn:de:0183-14dgpraec1213

Veröffentlicht: 3. September 2014

© 2014 Sukhova et al.
Dieser Artikel ist ein Open Access-Artikel und steht unter den Creative Commons Lizenzbedingungen (http://creativecommons.org/licenses/by-nc-nd/3.0/deed.de). Er darf vervielfältigt, verbreitet und öffentlich zugänglich gemacht werden, vorausgesetzt dass Autor und Quelle genannt werden.


Gliederung

Text

Background: Breast implants are widely used in cosmetic and reconstructive breast surgery; however, their use entails several complications. Among such complications, capsular contracture is not only the most common complication but also the one most often leading to revision surgery. In the past a several evaluated the impact of different risk factors on the origin of capsular contracture. As the implant surface provides the main interaction area between the implant and the surrounding tissue, we evaluated the impact of three different surface structures on capsular contracture establishing the Göttingen Minipig model as an animal model for evaluation of this complication. These three surface morphologies consisted of a smooth surface, a textured surface with large pores and a textured surface with small pores. We hypothesized that a change in surface morphology would lead to a change in the foreign body behavior targeted towards the implant.

Material and Methods: In this pilot study 6 female adult specific pathogen free (SPF) Ellegaard Göttingen Minipigs were subdivided into two groups including 2 minipigs in the 2-month group and 4 minipigs into the 4-month group. The operation was performed following the standard protocol of sterility requirements for breast augmentation procedures. In each animal a total of 6 implants (2 textured small, 2 textured large, 2 smooth) were placed by creating a separate subglandular pocket for each implant. The animals were weekly monitored for postoperative complications and the incidence of capsular contracture according to the Baker score. Before implantation and explantation procedure the blood level of leucocytes was measured and compared. For data collection of the skin flora of the minipigs a microbiological swab was taken from the surgical area before disinfecting. After explantation in both groups microbiological and biomechanical analysis of the capsules were performed. After opening the capsule a microbiological swab was taken from the implant surface. Furthermore a biopsy of the fibrotic capsule was processed by sonification-technique before culturing. The implant surface and corresponding part of the fibrous capsule were illustrated with scanning electron microscopy (SEM). For the biomechanical analysis the implants and the explanted capsules were subjected to compression testing with the help of an Instron 5848 microtester fitted with a 500N load cell at 37oC. The testing protocol comprised of a compression step up to 30% strain for the silicone implants and 15% strain for the explanted capsules at a rate of 0.6mm/min.

Results: The operation was well tolerated by all animals. No clinical signs of infection were noticed and the blood level of leucocytes was not elevated at any time of the study. The bacteria found on the implants and capsules corresponded to the bacterial skin flora of the minipigs. In the 2-month group all microbiological swabs from the textured small implant surfaces did not show any bacterial growth. However, in 3 of 4 (75%) capsules prepared by sonication technique a moderate growth of Staphylococcus lugdunensis was detected. The 2 of 4 (50%) large textured surfaces showed a moderate growth of bacteria, Staphylococcus xylosus with both methods and Staphylococcus lugdunensis only by sonication. Bacteria (Staphylococcus hyicus) in the smooth surface group were found in 1 of 4 (25%) fibrous capsules biopsies. The swabs were negative. In the clinical examination all these implants showed a Baker II Grade capsular contracture. In the 4-month group in 1 of 8 (12,5%) textured small surfaces an isolated growth of Staphylococcus hyicus in the swabs was determined. The same bacteria were found in the collagen capsule of this implant after sonication. In addition a growth of Staphylococcus xylosus was detected only by sonication technique. In 3 of 8 (37,5%) fibrous capsules from large textured surfaces a bacterial growth (Staphylococcus hyicus, Streptococcus viridans, Staphylococcus epidermidis) was detected. All the microbiological swabs were negative. 2 of 8 (25%) fibrous capsules from smooth implants showed positive bacterial growth (Staphylococcus capitis, Staphylococcus warneri) in the biopsy. In this group all the microbiological swabs were negative as well. In the clinical examination the implants showed a Baker score III capsular contracture. Graphs showing reaction force vs displacement were plotted for all implants and fibrous capsules. The results indicated that prior to implantation, implant ID 354_1307_lot6545104 had the highest stiffness, followed by 354-1307 and 354_7103. After placing these implants in vivo for 2 and 4 months, the overall stiffness of all implants decreased at different rates, with the stiffness of 354-1307 and 354_7103 becoming nearly the same. In terms of the fibrous capsules, the capsules formed around textured implants with large pores were the stiffest, followed by textured implants with small pores. The lowest stiffness was noted for smooth implants.

Conclusion: The minipig model is an appropriate model for the evaluation of capsular contracture due to the tissue reaction well comparable to human and the microbiological flora. Implants with bacterial contamination showed severe capsular contracture after 4 month of implantation. However, not all implants with severe capsular contracture showed a bacterial contamination. According to Baker score no significant difference could be shown between the different surface characteristics. Regarding the capsule stiffness which indicates the higher level of thick collagen fibers the lowest stiffness was noted for smooth implants.