BREAST IMPLANTS

Breast implants are commonly used in both aesthetic and reconstructive plastic surgery. In cosmetic surgery, breast implants are used to enlarge and/or lift the breasts. In reconstructive surgery, breast implants are used to recreate the breast mound. Multiple types of breast implants can be used, and breast implants can be placed either underneath or above the chest wall muscles. Over time, whether they are used for cosmetic or reconstructive purposes, all breast implants may need to be changed or removed. 

Breast Implant Types

Breast implants may be differentiated by filling type, outer texture, and shape. 

Filling Type

There are three different filling types for breast implants: saline, silicone gel, and cohesive gel. All three types of breast implants can be used for breast augmentation or breast reconstruction. The choice of filling is largely based on personal preference. 

Saline

Patients who choose saline implants tend to do so because they feel confident knowing that if the implant ruptures the saline that leaks into the body's tissues is safe. Saline is basically salt water, and it has many uses in medicine. Saline is often used to clean wounds, remove contact lenses, and help with dry eyes. Saline is injected into veins to treat dehydration, and it is also used to dilute other medications used intravenously. If a saline implant ruptures, the saline that spills into the breast tissue will be absorbed easily by the body. It will also be obvious that the implant is ruptured, as the breast with the ruptured saline implant will appear deflated. 

On the other hand, saline implants tend to feel firm, and they may also feel less natural. Saline implants last the longest when they are maximally filled or even slightly overfilled. Underfilled saline implants will have wrinkles, and those wrinkles are weak spots on the implants that can lead to rupture. The firmness of a saline implant will be particularly evident in women who have little or no breast tissue. 

Silicone Gel

Patients choose silicone gel implants because they want soft breasts that feel natural. Traditional silicone gel implants are prefilled with silicone gel, which is a thick, sticky fluid that is designed to imitate the feel of human fat. Silicone implants are much more pliable than saline implants, and the silicone looks and feels more like normal breast tissue.

On the other hand, silicone gel can be a problem if the implant ruptures. In 1992, silicone gel implants were taken off the market due to fears that they could be linked to cancer, autoimmune and connective tissue disorders such as lupus. In 2006, after extensive studies, the FDA approved the use of silicone implants again when no links were found between silicone implants and cancer, autoimmune and connective tissue disorders. If a silicone implant ruptures, however, it may be silent. Any free silicone tends to remain trapped in the patient's tissues, and the rupture may not be noticeable. The FDA recommends that women with silicone implants undergo breast MRI surveillance 3 years after implantation and then every 2 years after that. 

Silicone is supposed to be inert, but it can cause irritation to the tissues if the silicone gel leaks. Sometimes the only sign of rupture is a little pain or discomfort on the side of the ruptured silicone implant. Women with silicone implants who have discomfort should undergo breast MRI to evaluate for a potential silicone implant leak. 

Cohesive Gel

The newest type of breast implant is the cohesive silicone gel implant, or the "gummy bear" implant, which was approved by the FDA in 2012. Since the silicone in the new cohesive silicone gel implants is significantly more coherent than the silicone in traditional silicone gel implants, it is believed that the cohesive gel will hold together if the outer silicone shell ruptures - much like a gummy bear. 

The cohesive gel implant is softer than a saline implant but firmer than the traditional silicone gel implant. Since the silicone gel is more coherent, the cohesive gel implant tends to hold its shape because it is stiffer than traditional silicone gel. The cohesive gel implant will require the largest incision on the breast, because cohesive gel implants are less flexible than all other implant types and cannot squeeze through a small incision.

Outer Texture

All breast implants have an outer silicone shell. The outer silicone shell in breast implants come in two different textures: smooth and textured. 

When the outer shell is smooth, the breast implant can more easily move or spin in the breast pocket. Smooth implants are less prone to infection, because there are no irregular crevices for the bacteria to hide. For patients with very little or no breast tissue, smooth implants minimize risk of visible rippling because the breast tissue cannot attach to the smooth surface. Smooth implants are more likely to develop capsular contracture, however. Over time, the slick capsule that forms around a smooth implant can shrink and contract, leading to a capsular contracture that is hard and painful. 

When the outer shell is textured, the breast tissue can grow onto the surface of the implant. This allows the implant to scar in place, so that it does not move around in the breast pocket. While a capsule will form around all implants, textured implants reduce the risk of capsular contracture. Textured implants do have a slightly increased risk of infection, however, and textured implants also increase the risk of rippling in women with minimal or no breast tissue since the implant is very adherent to the breast tissue and skin. 

Implant Shape

Implants can be either round or teardrop shaped. Round implants are basically circles, and the circular implants can project to different heights from the chest wall. The higher the projection, the farther the breast will stick out from the chest wall. Round implants can be either smooth or textured, because if the implant moves or spins it does not change the shape of the implant. Teardrop shaped implants have less projection at the top of the breast and more projection at the bottom of the breast, much like a natural breast. Teardrop shaped implants should always be textured, because if the implant were to move due to a smooth slippery surface the breast would appear misshapen. Cohesive gel implants are generally textured teardrop shaped implants because they retain their shape and it is believed that maintaining a teardrop shape looks the most natural.

Implant Placement

Breast implants can be placed below the pectoralis muscle or above the pectoralis muscle.

Subpectoral

In both breast augmentation and breast reconstruction, breast implants are commonly placed under the pectoralis muscle. The advantage of placing implants underneath the pectoralis muscle is that it provides additional soft tissue coverage over the implant, which can be important when someone has very little or no breast tissue. The additional soft tissue coverage can soften the implant edges that might otherwise be visible and palpable. In addition, the action of the muscle on top of the implant can help shape the top portion of the implant so that it does not look artificially full. Finally, the squeezing action of the muscle on the implant can reduce the incidence of capsular contracture.

The action of the pectoralis muscle flexing over a breast implant can lead to hypermobility. When the muscle presses down on the implant, it can temporarily deform and change the shape of the implant and move it upward or to the side. In addition, since the pectoralis muscle is normally flat against the chest wall, the presence of an implant underneath the pectoralis muscle can feel tight or even painful. For most women, the discomfort usually improves over time, but some women never become accustomed to the tight feeling of an implant underneath the pectoralis muscle.

Prepectoral

Breast implants can also be placed above the pectoralis muscle, in the same location as the breast tissue. In breast augmentation, a breast implant over the pectoralis muscle is called a "subglandular" or "prepectoral" implant, because it is under the breast gland but over the pectoralis muscle. In breast reconstruction, a breast implant over the pectoralis muscle is just called a "prepectoral" implant, because it is over the pectoralis muscle but there is no glandular breast tissue after a mastectomy.

Prepectoral breast implants have the advantage of being more comfortable, because there is no tightness from a foreign body being placed underneath the pectoralis muscle. There is no hypermobility with the implant being deformed and displaced by the pectoralis muscle, because the breast implant is over the muscle. The disadvantage is that there is not as much soft tissue coverage. Thus, it may be easier to see the outlines of the breast implant itself. This can be addressed by using a shaped implant with an acellular dermal matrix (ADM) wrapped around the implant. The ADM provides an extra layer of soft tissue coverage over the implant, and can also soften the edges of the implant itself.

Breast reconstruction with prepectoral cohesive gel implants wrapped in ADM is the newest type of implant-based breast reconstruction. ADM is composed of the dermal layer of skin that has been stripped of reactive cell components but retains the biologic qualities and structure of natural collagen. ADM eventually integrates with the body and is replaced with the patient's own tissue. Since the implant is placed above the muscle, the normal pain and tightness from a subpectoral implant is eliminated. In addition, the cohesive gel implant retains a teardrop shape underneath the thin mastectomy skin.

Complications of Breast Implants

Almost all breast implants used in the United States have a 10-year warranty. While some implants can last for decades, many implants need to be changed in a much shorter period of time. Implants are not expected to last forever. According to data gathered by the implant manufacturers, about half of breast implants need to be changed within seven years. The most common reasons for implant problems include capsular contracture, rupture, and infection.

Capsular Contracture

Capsular contracture is scarring that occurs around the breast implant. All breast implants - smooth, textured, round, shaped, above muscle, below muscle - will develop a capsule. Since implants are a foreign body, the body tries to wall off the implant by creating a capsule around it as a barrier from the implant. The capsule can be something that is soft and flimsy - almost like a film that is not noticeable. Or it can become firm and painful - almost like a hard shell that feels like it shrinks and contracts over time. When an implant develops a hard, painful capsular contracture, it is not dangerous in and of itself. The discomfort, however, may lead women to want the implant and the capsule removed in its entireity. 

An en bloc capsulectomy can be performed to remove the implant and the capsule in one piece. A complete en bloc capsulectomy is a painstaking and meticulous procedure that removes every bit of the capsule, including the section that may be very adherent to the chest wall and ribs. A partial capsulectomy leaves pieces of the capsule in the breast pocket. The surgical dissection from an en bloc capsulectomy is an irritant to the remaining breast tissue, and will stimulate fluid production from the body. After an en bloc capsulectomy, it is usually necessary to place drains to allow the fluid from the breast pocket to exit the body. If a new implant is being placed, it usually placed in a fresh space. In other words, if the original implant was placed subpectorally, the new implant would be placed prepectorally. Conversely, if the original implant was placed prepectorally, the new implant would be placed subpectorally. 

For patients who undergo implant removal and en bloc capsulectomy and do not want an implant replaced, drains will need to be left to drain fluid in for a longer period of time. The body does not like empty spaces, and will try to fill the potential space with fluid. For patients who still have breast tissue, they may need a breast lift, or mastopexy, to rearrange any remaining breast tissue to recreate a breast mound. Otherwise, the stretched-out breast skin that has lost the volume from the implant may look empty, deflated, and unsightly. Some patients who do not want implants but need more volume may benefit from fat grafting to add bulk to their breast tissue. Fat grafting involves liposuction from another part of the body, processing and purifying the lipoaspirate, and then injecting the purified fat cells into the breast tissue to add volume.

For patients who have no breast tissue after implant removal and en bloc capsulectomies because they have undergone mastectomies, they can decide to undergo a new breast reconstruction with implants or with their owntissue. Autologous tissue breast reconstruction after mastectomy is best performed with flaps, in which skin and fat from another part of the body is transferred to the chest with its own blood supply to create a new breast. The gold standard in autologous tissue breast reconstruction is perforator flaps.

Rupture

Both saline and silicone implants can rupture. All implants - even saline implants - have a silicone shell, and the silicone shell can wear out over time. When a saline implants ruptures, it is quite obvious as the implant simply deflates. In addition, the saline that spills into the tissues should be safe, as saline is the same fluid that is used intravenously to rehydrate the body. When a silicone implant ruptures, however, it may be silent. Furthermore, silicone is supposed to be inert, but the ruptured silicone gel can cause irritation and inflammation to the surrounding breast tissue that can worsen over time. 

Both ruptured saline and silicone breast implants should be removed and/or replaced. In the operating room, removing a ruptured saline implant is relatively straightforward. Removing a ruptured silicone implant, however, is more challenging because the thick sticky gel can be difficult to remove. If the silicone gel spills into the tissues, it may be necessary to resect some breast tissue. This can leave breasts appearing dimpled, wrinkled, sagging, and otherwise deformed, and the remaining breast tissue may not return to its original shape. If a ruptured silicone implant is replaced, there may be a higher risk of complications compared to the first time. If an implant is not replaced, it may be necessary to perform other procedures to recreate a breast shape.

Infection

Since breast implants are a foreign body, they do not have a blood supply. If a patient develops breast infection, the implant cannot bring white blood cells and other natural defenders of the body to fight the infection. If the infection is a skin infection only, such as redness from cellulitis, then it may be possible to control the infection with antibiotics. If a breast implant itself becomes infected, however, because bacteria is seeded on the implant, then it needs to be removed. 

Extrusion

Since breast implants are a foreign body, they can create pressure against the breast skin from the inside. This constant pressure occasionally leads to erosion of the breast skin so that implant starts to push through the skin. When the breast implant pushes through the skin to the outside world, this is called extrusion. Although rare, extrusion is most common among women who have undergone radiation treatment for cancer. This is because radiation therapy damages the skin, and makes it more difficult to heal. Extrusion can also occur in breasts that have not undergone radiation if the patient or her skin has been otherwise compromised.

Anaplastic Large Cell Lymphoma

The FDA is currently collecting data on a possible association between anaplastic large cell lymphoma (ALCL) and breast implants. ALCL is a rare type of non-Hodgkin lymphoma (NHL), a cancer involving the cells of the immune system. The incidence of ALCL in the breast is 3 cases of ALCL in 100 million women (0.000003%). The worldwide incidence of ALCL in patients with breast implants is estimated to be about 60 cases of ALCL in 5-10 million women (0.0006-0.0012%). The incidence of ALCL in women with breast implants may be slightly overestimated, because some of the data that has been collected may be duplicate cases.

ALCL is extremely rare, but women with breast implants may have a very small but increased risk of developing ALCL in the scar capsule surrounding the breast implant. There is currently no trend of implant type (saline vs silicone) or implant reason (aesthetic augmentation vs reconstruction) associated with a smaller or greater risk of ALCL. Textured implants may be at slightly greater risk for ALCL than smooth implants, but findings are not conclusive. When ALCL occurs with breast implants, it is identified most frequently in patients undergoing implant revisions for late onset, persistent seroma, which is a fluid collection that develops around the implant. Thus, the FDA does not currently recommend prophylactic breast implant removal in patients without symptoms or other abnormalities. Since the risk of ALCL appears to be quite small and inconclusive, breast implants are still approved in the USA when used as labeled for breast augmentation or breast reconstruction.

Summary

Breast implants are commonly used for both aesthetic breast augmentation and breast reconstruction. Both saline and silicone breast implants have been widely studied by the FDA, and are currently approved for use in the USA. Prepectoral cohesive gel breast implants are the newest type of implant-based breast reconstruction, and they have solved some of the problems associated with previous types of implant-based breast reconstruction. Breast implants are not without problems, however, and careful consideration should be given to the risks prior to placing breast implants. Patients should also know that breast implants are not expected to last forever, and they may need to be removed or replaced over time.