We would like to thank Dr. Kim for sharing his questions concerning our article.1 We do believe that shear forces delaminate or fracture the developing capsule, thereby contributing to double-capsule formation. Our studies have shown that microfractures occur at “sites of weakness” within capsules, caused by an inflammatory cellular response to the implant; it is our belief that application of shear forces to the capsule at these microfracture points induces a delamination of the single capsule into two distinct layers.2
The finding of significantly higher bacterial counts and biofilm on the prosthesis interface than in the intercapsular space serves, in our opinion, to support our hypothesis. We believe that all bacterial contamination occurs at implantation; these bacteria are therefore likely present in all patients at the prosthesis interface and typically quiescent. If the process of double-capsule formation were to occur directly at the implant-capsule interface, spillage of this biofilm and bacteria would result in similar bacterial loads at the prosthesis interface and in the intercapsular space. The fact that this does not occur supports the assumption that double-capsule formation occurs more externally than at the implant-capsule interface. Although we do find the variance of biofilm load in different spaces telling, we do not believe there to be a direct causality between biofilm and double-capsule formation; however, biofilm is most likely a key factor in the pathophysiology along with mechanical forces and foreign body reaction.3,4 We had indeed previously indicated the plausibility of Hall-Findlay’s theory that separation occurred at the implant surface itself.5 However, our more recent research on periprosthetic capsule architecture and bacterial cell phenotype and biofilm load supports the capsular delamination model of double-capsule development.2,6
As for the findings of double capsules in the multiple types of implant shell, we do believe that double capsules are more common in aggressively textured implants because of the higher cohesion and tissue ingrowth between implant and capsule seen with this type of texturing. Aggressively textured surfaces, such as Biocell (Allergan, Inc., Dublin, Ireland), are more likely to cause both inflammatory cell reactions and subsequent delamination of the immature ingrown capsule in response to mechanical shear forces. In contrast, smooth textured implants may more easily glide within their primary capsule in response to shearing forces and are therefore less likely to form double capsules.
Dr. Danino is a consultant and speaker for Allergan, Inc. None of the other authors has any commercial associations or financial interests to declare with respect to any of the information or products presented in this communication.
Michel Alain Danino, M.D., Ph.D.Laurence S. Paek, M.D., M.Sc.Arij Elkhatib, M.D.Faisal Obeid, M.D.Joseph Boumerhi, M.D.Division of Plastic SurgeryCentre Hospitalier de l’Université de MontréalUniversité de MontréalMontreal, Quebec, Canada
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2. Efanov JI, Giot JP, Fernandez J, Danino MA. Breast-implant texturing associated with delamination of capsular layers: A histological analysis of the double capsule phenomenon. Ann Chir Plast Esthet. 2017;62:196201.
3. Maxwell GP, Brown MH, Oefelein MG, Kaplan HM, Hedén P. Clinical considerations regarding the risks and benefits of textured surface implants and double capsule. Plast Reconstr Surg. 2011;128:593595.
4. Allan JM, Jacombs AS, Hu H, Merten SL, Deva AK. Detection of bacterial biofilm in double capsule surrounding mammary implants: Findings in human and porcine breast augmentation. Plast Reconstr Surg. 2012;129:578e580e.
5. Hall-Findlay EJ. Breast implant complication review: Double capsules and late seromas. Plast Reconstr Surg. 2011;127:5666.
6. Giot JP, Paek LS, Nizard N, et al. The double capsules in macro-textured breast implants. Biomaterials 2015;67:6572.