Introduction

It is estimated that over 300 000 primary breast augmentations were performed in the United States in 2009, and therefore there are now over 3 million women with augmented breasts in this country.¹^–³ Based on current data, between 15% and 30% of these women, will have a reoperation within 5 years of their initial procedure.¹^–³ Unfortunately, this rate climbs to 35% in patients with a prior history of revisionary breast augmentation.⁴ As procedures become more complex in nature and number, new techniques and solutions are required of surgeons who perform these challenging operations to improve long-term patient outcomes.

Capsular contracture has historically been the most common complication of aesthetic and reconstructive breast surgery and remains the primary reason for most revisionary surgeries.^2,^3,^5,⁶ While increasing data suggests capsular contracture can be minimized in primary augmentation by technical detail including precise, atraumatic, bloodless dissection; appropriate antibiotic breast pocket irrigation; and minimizing any points of contamination during the procedure,^4,⁷ treatment of an established capsule remains even more challenging than the application of these techniques alone.

The enforcement of the US FDA restrictions on silicone gel implants in the early 1990s led American surgeons to use saline implants.¹ While prior to the 1992 “moratorium”, the majority of silicone gel implants were placed in the subglandular position, saline implants (due to their palpability) began to be placed under the muscle in an effort to conceal the untoward contour irregularities of these implants.⁸ As a number of these implants were of larger volumes, many patients experienced thinning of breast parenchyma and the overlying soft tissue, whether the implants were in subglandular or subpectoral positions. The thinned tissues, in turn, can lead to long-term complications, which had led to some key drivers of revisionary breast surgery.

The four primary reasons (or “Drivers”) for aesthetic revision surgery in the Pre-Market Approval (PMA) studies were as follows:⁹ (1) capsular contracture, (2) implant malposition, (3) ptosis, and (4) implant visibility or palpability. Frequently, these indications were not singularly distinct, but were combined with two or more being present in a given patient.

Hints and tips

• There are four key drivers to revisionary breast surgery: (1) capsular contracture; (2) implant malposition; (3) ptosis, and (4) implant visibility or palpability. Frequently, these indications are not singularly distinct, but were combined with two or more being present in a given patient.

• Capsular contracture is the most common driver for revisionary breast surgery.

• Site change and acellular dermal matrix are key for successful outcomes in revisionary breast surgery.

History

Historically, our options for revision and improvement have included: replacing saline implants with gel implants, capsulorrhaphy, use of capsular flaps, or performing a site change operation. The site change principle, described in the mid-1980s, combined total or partial capsulectomy with conversion to a different pocket (generally a subglandular to subpectoral site change) for the replacement implant.¹⁰ While site change procedures have been successful, none of these procedures alone have resulted in complete resolution of the described complaints

As change was necessary to improve clinical outcomes in this population of breast revision patients, application and development of newer techniques and technologies were pursued.

In our experience, the majority of breast revisions require a new pocket for the new implant. Since many patients have had implants in multiple pockets, and as the majority of implants in revisionary patients today are already in the subpectoral position, we developed (in 1991) the “neopectoral pocket” concept to create a new pocket in the “subpectoral-precapsular space”.¹¹ Initially developed for inferior malposition, we also applied our concept to medial malposition, capsular contracture, ptosis, and conversion of round to anatomical shaped implants (demanding a snug, hand-in-glove “fit”). The detailed operative technique of creation of the neopectoral pocket has been described in a previous publication.⁸ For patients presenting with implants in the subglandular position, a sub-pectoral site change is utilized.

Notwithstanding the importance of the site change concept, the most important addition to our clinical armamentarium has been the utilization of acellular dermal matrix as a regenerative construct to help solve these challenging clinical presentations.¹² The successful use of acellular dermal matrices (ADMs) has been reported in a range of clinical settings including abdominal wall repair, hernia repair, facial and eyelid surgery, cleft palate repair, soft tissue augmentation, tendon repair, ulcer repair, vaginal sling repair, and breast reconstruction.¹³^–²³ While its use in reconstructive expander and implant breast surgery has become a standard of care, its use in aesthetic revisionary breast surgery has evolved more slowly,²⁴^–²⁶ and has only recently gained widespread adoption.²⁴ The senior author has been a pioneer in this field over the last 10 years utilizing virtually every commercially available ADM product in various sizes, shapes, and thicknesses to better clinically define regenerative and biomechanical material properties and refine more clearly the specific clinical indications and techniques of use.

Basic science and disease process

Acellular dermal materials, biologically derived from allograft and xenograft, when placed in the human body, are thought to serve as a regenerative scaffold, promoting the organization of the healing process. These materials have become popular in breast cancer reconstruction, where they are said to serve as a tissue extension or tissue replacement (“soft-tissue patch”) following cancer extirpation of the breast (so-called “sling technique”).^22,^23,²⁷

Our work with acellular dermal matrix (ADM) began in revisionary aesthetic breast surgery, attempting to prevent capsular contracture, rather than as a tissue replacement in breast reconstruction. Having previously employed “host-compatible” implant surfaces,²⁸ here we have utilized a similar concept in our clinical approach to breast revision: a dermal regenerative interface engaging the surface geometric contour of a breast implant.

Understanding the changes that occur in the breast tissue is part of management of the problem at hand. Following breast surgery, many factors play a role in the changes that are observed in the breast form and at times are considered late complications of breast augmentation. Patients lose or gain weight which contributes directly to the breast shape. In addition, some patients may undergo surgical or nonsurgical menopause which has deleterious effects on the wellbeing of the skin, causing thinning of the breast skin, decreased elasticity, and increased ptosis. There are other physiological factors that a play a big role in the pathophysiology of the changing breast forms. Patients present with any of the following complaints: capsular contracture, implant malposition, ptosis, and implant visibility or palpability. Interestingly, patients with capsular contracture do not realize the primary reason for the deformity of their breast and present to the office for other complaints as stated above.

Capsular contracture has plagued plastic surgery as the most common complication of aesthetic and reconstructive breast surgery for many years.^2,⁵ The majority of revisionary breast surgeries are performed to correct capsular contracture.^2,⁶ Many etiologies have been proposed for this process, and it is clear that prevention of it in primary cases includes sound techniques – including precise, atraumatic, bloodless dissection; appropriate triple antibiotic breast pocket irrigation; and minimizing any points of contamination during the procedure.^4,⁷ Treatment of an established capsule can be more challenging, and multiple techniques have been utilized for this. The bottom line for any pathophysiological process is to understand the disease at the cellular level. In this case, it is perspicuous that at the cellular level, capsular contracture is most likely caused by any process that will produce increased inflammation, leading to formation of deleterious cytokines within the periprosthetic pocket. Consequently, in addition to all of the techniques for treating and preventing capsular contracture described by many of our colleagues,^4,^5,^8,²⁹^–³⁵ we believe that the addition of ADM is another modality in fighting the evolution of the capsule. ADM can counteract the inflammatory process, adding additional availability of tissue in-growth and controlling the interface of the pocket.

Acellular dermal matrix

Use of acellular dermal matrices have been popularized in both breast and abdominal wall reconstructions and has been reported in a range of clinical settings.¹³^–²³ In reconstructive cases, it has been used to replace tissue, extend existing tissue, or act as a supplement. In aesthetic cases, it has been used to correct implant rippling and displacement, including symmastia.^25,^26,³⁶

Immediate breast reconstruction using tissue expanders or implants has become one of the most commonly used surgical techniques, which has made visible rippling and contour deformity a more frequently encountered problem.²⁷ The recent use of allogeneic tissue supplements avoids the problems of autologous tissue coverage and provides camouflage, thus decreasing rippling, and increasing soft tissue padding.²⁷

Rising demand has spurred a tremendous growth in the number of available ADMs. Published research regarding the use and efficacy of acellular dermal matrices in immediate breast reconstruction is growing but has not kept pace with the market explosion. The many features and indications of all ADMs can confound the decision making process for surgeons who want to incorporate ADMs in their treatment armamentarium.

Acellular dermal matrices can be categorized under either xenograft or allograft in origin. All are produced with a similar objective of removing cellular and antigenic components that can cause rejection and infection. The lack of immunogenic epitopes enables the evasion of rejection, absorption, and extrusion.^14,^15,²³ Production processes allow the basement membrane and cellular matrix to remain intact. This scaffold is left in place to allow in-growth of host fibroblasts and capillaries to eventually incorporate as its own. Much of this scaffold matrix consists of intact collagen fibers and bundles to support tissue in-growth, proteins, intact elastin, hyaluronic acid, fibronectin, fibrillar collagen, collagen VI, vascular channels and proteoglycan – all of which allow the body to mount its own tissue regeneration process.^14,^15,^22,²³

All ADMs are FDA cleared for homologous use only. Although features and processing may vary between ADMs, the success of the product will ultimately depend on its ability to meet the desired characteristics of a model ADM for revisionary breast surgery. A list of ADMs that are available on the market for a variety of applications are included in Table 4.1.

Table 4.1 Comparison of different commercially available acellular dermal matrices

Published literature

AlloDerm is clearly in the forefront regarding published literature concerning ADMs for immediate breast reconstruction. A PubMed search using specific brand names and breast reconstruction reveals the majority of the publications involving AlloDerm. Ten of these papers relate directly to adjunctive ADM treatment of immediate breast reconstruction using AlloDerm,^14,^15,^22,^23,^27,³⁷^–³⁹ Dermamatrix,⁴⁰ and Neoform.⁴¹ All of these papers are recent publications, the oldest dating from 2005.¹⁴ All are noncontrolled, retrospective case series. PubMed searches were also performed matching each name of all other human and xenograft ADMs – FlexHD, Allomax, Surgimend, Enduragen, Synovis, Permacol, and Strattice – with breast reconstruction and revealed no listings. It is likely that studies are underway and not yet completed.

As new products are introduced to the market place, it is always crucial to understand the science behind each technology. The device industry should be evaluated as critically as the pharmaceutical industry, questioning the science and understanding the mechanism of action.

When evaluating ADMs critically, it is important that we understand the differences on how the body responds to the different materials. Not all soft tissue materials elicit the same biological response. There are three unique processes that can take place with any tissue material that is placed into the body, whether it’s a biologic or synthetic material. All products placed into a body elicit an inflammatory response with involvement of multiple cytoprotective and cytotoxic cytokines. The continuum of this reaction is controlled by the intrinsic mechanism unique to each scaffold.

Regeneration

With this process, the product is accepted by the body where the intact tissue matrix integrates and becomes part of the host through rapid revascularization and cellular repopulation. This is the process that is most beneficial and important to obtain good outcomes in breast surgery and perhaps the reason why we see less peri-prosthetic capsular contracture.

Resorption

This is the process where the human body attacks the replaced tissue and breaks it down by completely eliminating it, while depositing scar in its place. This is commonly seen with absorbable mesh products.

Encapsulation

During this process, the product is encapsulated through an inflammatory response which is unable to break down the product due to its synthetic nature. Therefore the product is encapsulated and walled off from the host. This process is not unique to synthetic products, but applies to any foreign body (e.g., pacemaker, implants) that is placed into the host.

The goal of regenerating tissue is to recapitulate in adult wounded tissue the intrinsic regenerative processes that are involved in normal adult tissue maintenance.⁴² Scar does not have the native structure, function, and physiology of the original normal tissue. When a wound exceeds a critical deficit, it requires a scaffold to organize tissue replacement. Depending on the type of scaffold that is in place, different processes as described earlier will respond. At this point, the intrinsic factors of the ADM will be important to aid in each specific regenerative or reparative process. While regenerative healing is characterized by the restoration of the structure, function, and physiology of damaged or absent tissue, reparative healing is characterized by wound closure through scar formation.⁴² All biologic scaffolds are not the same because of differences in the methods used to process them – materials that encapsulate and scar do not offer the benefits of regenerative healing but lead to suboptimal results.