Breast implants (see the image below) are designed for use in cosmetic enhancement and reconstruction.
Saline breast implants
Saline breast implants are FDA approved for breast augmentation in women aged 18 years or older and for breast reconstruction in women of any age. These implants contain a silicone outer shell filled with sterile saline and have the following features:
May be empty initially (and filled during the procedure of implantation) or pre-filled
Available in different sizes
Have smooth or textured surfaces to their shells
Can be placed with integrated remote-fill ports: Also permit postoperative adjustment of implant saline volume
Less costly than silicone-filled products
Implant ruptures quickly detectable
Possible visible implant rippling on surface of augmented breast in women with thin breast tissue
Silicone gel-filled breast implants
Silicone gel-filled breast implants are FDA approved for breast augmentation in women aged 22 years or older and for breast reconstruction in women of any age. These implants have a silicone outer shell filled with silicone gel of varying consistencies and feature the following:
Available in different sizes
Have smooth or textured surfaces to their shells
More costly than saline-filled implants
Have a more natural feel than saline-filled implants
Less noticeable rippling in thin-skinned augmentations
Cannot be placed through a transumbilical incision (unlike remote-fill ports) but can be implanted through periareolar, inframammary and transaxillary incisions
Surgical incisions and dissection planes
The 5 surgical approaches to placing breast implants include inframammary, periareolar, transareolar, transaxillary, and transumbilical incision.
Breast implants can be placed either subglandular, submuscular (underneath the pectoralis muscle), or in a dual plane with the superior part of the implant being covered by muscle and the inferior part under the gland.
In general, most companies guarantee breast implants for 10 years in case of rupture. The FDA recommends that women with silicone gel implants get breast imaging with MRI to detect silent rupture 3 years after implantation and every other year after that.
With saline implants, patients should proceed with their recommended mammography protocol for breast cancer screening. Moreover, they can develop capsular contracture over time, and women should return to the plastic surgeon regarding any concerns or questions regarding this.
Types of complications
In general, complication rates are almost always higher in breast reconstruction than in primary cosmetic surgery.
Studies offer contrasting findings regarding the risk of capsular contracture with different breast implant design features. For example, some reports indicate decreased capsular contracture rates with textured implants relative to smooth implants, such as macro-textured implants [1, 2] that include subglandular textured implants  but not medium- or micro-textured ones  nor submuscular textured implants. 
Other studies, however, found no significant difference between smooth and textured implants in the subglandular plane  or between smooth and large-pore textured saline implants. In addition, in the setting of irradiated, reconstructed breasts, the capsular contracture rate remained quite high, even with textured implants. 
In addition to capsular contractures, the following complications may arise following breast implant procedures:
Hematoma: Blood collection within the breast that often causes localized swelling and pain necessitates evacuation
Seroma: Thin fluid collection around the implant
Wound infection: Most commonly due to Staphylococcus aureus from the skin or lactiferous ducts but also by more rare pathogens such as Candida albicans, Curvularia spp , Aspergillus niger, mycobacteria, and Clostridium perfringens
Changes in nipple and/or breast sensation: Hypersensitivity or hyposensitivity
Implant rupture: Incidence of about 5-10% at 10 years
Issues with lactation: Difficulty breastfeeding in up to 20% of women 
Anaplastic large T-cell lymphoma of the breast: Rare; potential association with breast implants without proof of causation 
Breast implants are designed for use in cosmetic enhancement and reconstruction. They come in many different shapes, sizes, projections, and textures and with different fill materials.
Saline breast implants contain a silicone outer shell filled with sterile saline. Certain implants are empty and thus are filled during the procedure of implantation; others come pre-filled. Saline-filled implants come in different sizes and have either smooth or textured surfaces to their shells. Integrated remote-fill ports can be used and permit postoperative adjustment of implant saline volume. These devices are FDA approved for breast augmentation in women age 18 or older and for breast reconstruction in women of any age.
Silicone gel-filled breast implants have a silicone outer shell filled with silicone gel of varying consistencies. They come in different sizes and come with both smooth or textured shells. Silicone gel–filled breast implants are approved for breast augmentation in women age 22 or older and for breast reconstruction in women of any age.
The surgeon and patient can select from various implant projection profiles depending on their cosmetic goals.
Breast implants are FDA class III devices (ie, they require premarket approval).
The major US manufacturers of breast implants are Mentor Corp (Santa Barbara, CA), Allergan (Santa Barbara, CA), and Sientra (Santa Barbara, CA; see the images below). In 2013, the FDA approved the MemoryShape (Mentor) silicone gel–filled breast implant for breast augmentation in women aged at least 22 years and for breast reconstruction in women of any age. [9, 10]
Saline versus silicone gel
Saline implants have the advantage of decreased cost compared to silicone-filled products. Some products can also be filled from a distant port, which enables a surgeon to place them through a transumbilical approach. Moreover, if implant rupture occurs, this is usually more quickly recognizable. In patients with thin breast tissue, however, a higher chance exists that implant rippling will be visible on the surface of the augmented breast.
In contrast, silicone implants cost more but are widely believed to have a feel that is more natural and rippling in thin skinned augmentations is less noticeable. These cannot be placed through a transumbilical incision, but can still be implanted through periareolar, inframammary and also transaxillary incisions.
A literature review by Balk et al indicated that evidence for the long-term health effects of silicone gel breast implants is still inconclusive, with the evidence in many studies applying to breast implants in general and not specifically to the silicone gel type. However, a possible relationship was seen between silicone gel implants and a decreased risk for primary breast and endometrial cancers, as well as an increased risk for lung cancer, rheumatoid arthritis, Sjögren syndrome, and Raynaud syndrome. [11, 12]
Textured versus smooth
Textured versus smooth relates to the implant surface type and is a highly debated topic with regard to its effect on capsular contracture. In theory, textured surface implants may decrease capsular contracture. The mechanism is thought to be the byproduct of breast capsule growth onto the implant surface, which, because of its texture, encourages disorganization of capsular fibres and thus also the resultant force vectors of contracting fibers.
Round versus anatomical
Experience with anatomically shaped implants is evolving. Theoretically, these implants may provide a more natural shape to the augmented or reconstructed breast. Thus far, there does not appear to be a large cosmetic advantage in teardrop-shaped implants in the breast reconstruction patient, but they might be more useful in certain cosmetic cases. The potential disadvantage to these implants is that they can rotate within the breast capsule and leave the patient with an inferior cosmetic outcome.
Mentor Spectrum implants come in smooth round, textured round, and textured teardrop shapes. Smooth, round devices are the most commonly used as they ripple less than the textured variety. The novel advantage of these devices is that they permit the surgeons to adjust the implant size up to 12 months postoperatively. This is particularly helpful if a woman is unsure about what size breast she desires. Size change is accomplished via saline injection into a subcutaneous injection port or via an exteriorized injection port. The exteriorized port needs to be inserted via a long subcutaneous tunnel to prevent retrograde infection and should be removed within 1 week postoperatively.
See the list below:
Saline implants are indicated for breast augmentation in women age 18 or older and for breast reconstruction in women of any age.
Silicone implants are indicated for breast augmentation in women age 22 or older and for breast reconstruction in women of any age.
A recent study in the English literature has shown decreased capsular contracture rates with macro-textured implants but not with medium or micro-textured ones.  In a clinical meta-analysis of subglandular implants, textured implants were associated with less capsular contracture at 1 year (relative risk, 4.16; 95% CI, 1.58 to 10.96), 3 years (relative risk, 7.25; 95% CI, 2.42 to 21.69), and 7 years (relative risk, 2.98; 95% CI, 0.86 to 10.37) of follow-up. 
Another meta-analysis that same year noted an 81% risk reduction for contracture with textured implants, except in the case of submuscular implants, which showed no statistically significant difference.  In the international literature, a meta-analysis of textured versus smooth implants indicated a lower capsular contracture rate with the former at 1 or 10 years after breast augmentation.  A literature review by Liu et al also reported that textured implants reduce the likelihood of capsular contracture. 
Despite these reviews, literature that describes no significant difference between smooth and textured implants in the subglandular plane also exists. One particularly convincing article showed no significant contracture difference at 7.5 years between smooth and fine-textured implants. Both devices were placed simultaneously in different breasts of the same patient.  In fact, slightly more patients in this study preferred the smooth implants over the textured ones. A similar study by the same group showed no difference between smooth and large-pore textured saline implants. In the setting of irradiated, reconstructed breasts, the capsular contracture rate remains quite high, even with texture implants. 
Smooth Spectrum implants have an extremely low rupture rate of 1.1% over 7 years, which is likely due to the valve competence. This is compared to 2-3% for smooth saline and 12% for textured saline.  In a study of 322 cases using the Smooth Spectrum implant for breast reconstruction over 14 years, 19% developed capsular contracture, 5% had seroma or hematoma, and 2% had periprosthetic infection. 
One must bear in mind that complication rates are almost always higher in breast reconstruction than in primary cosmetic surgery. In a study evaluating cosmetic use, 9% of patients had saline volume reduced, and 79% had volume added postoperatively.  Patients were grateful to be able to continue to participate in the size decision-making process after surgery. The only difficulty noted in this study was a periprosthetic seroma that caused confusion as to whether volume should be added, removed, or left alone. For this reason, all patients should have drains when using the exteriorized port since the breast size decision must be made within a week after surgery, before the port is removed.
Breast implants can be placed surgically through a variety of incisions, each with associated advantages and disadvantages. The five approaches include inframammary, periareolar, transareolar, transaxillary, and transumbilical incision.
The inframammary approach (IM) uses an incision at the inferior fold of the breast. The incision is hidden under the breast mound but can be visible. It enables the surgeon good control and flexibility with implant pocket creation and device placement of all sizes.
The periareolar approach (PA) involves an incision along the inferior half of the outer circumference of the nipple. This can be better hidden than the inframammary method but can potentially experience some hypopigmentation compared to the darker color of the areola. If this occurs and is bothersome, a medical tattoo can be used to change the color. This incision provides good access to adjust the inframammary fold and can be incorporated into a simultaneous mastopexy procedure.
Compared to the IM approach, however, the periareolar incision can limit exposure for pocket dissection as well as the size of the silicone implant that can be placed. The latter potential difficulty can be abetted with the use of a funnel system. Moreover, the proximity of the incision to the incised lactiferous ducts raises the bacterial contamination risk to the implant. This might, in turn, raise the risk of capsular contracture and implant infection, although the data regarding these problems are controversial. The transareolar approach has similar advantages and disadvantages to the PA approach. This incision can be hidden well in a wrinkle within the nipple-areola complex.
Some controversy exists regarding changes of nipple sensation, both hyper and hyposensitivity, following breast augmentation. The nipple and areola are innervated by the lateral and anterior cutaneous branches of the second to fifth intercostals nerves, which subsequently join the subdermal plexus. Many surgeons have had more concern with the PA incision theoretically because of the proximity of the incision to the nipple. However, a recent study has shown that the only difference between the IM and PA incisions is a decreased sensation at the inferior pole of the breast. When changes occur, sensation usually returns after 6 months. Patients who were most effected by sensory changes were over age 35. 
The transaxillary technique involves a short transverse incision in the axilla. Although some surgeons may use this approach routinely, it might be best suited for patients with a poorly defined inframammary fold and small areolar diameter. Although the incision is hidden well, the disadvantages of this technique is that implants can tend to ride high on the chest wall; placing large silicone implants without the use of a funnel device can be challenging and controlling the inframammary fold precisely can be difficult. With the assistance of endoscopic equipment, however, one study noted a decreased incidence of implant malposition from 8.6% to 2%. 
Tebbetts also showed that his Baker III/IV capsular contracture rates were lower with 4.2% versus 1.3% for blunt and endoscopic dissection, respectively.  If any revision surgery needs to be done in the future, the surgeon usually needs to place an incision in a different location on the breast. This approach also carries the risk of injury to the intercostobrachial and medial brachial cutaneous nerves, which supply sensation to distal medial portion of the arm.
The transumbilical (TUBA) approach hides the incision remotely through the umbilicus. Access to the breasts is gained with long, blunt dissection instruments without the ability to visualize the breast pockets. Saline implants are subsequently inserted through tubes into the breasts and filled to the desired sizes. The major disadvantages of this approach compared to other methods are that control of the inframammary fold position is unreliable, silicone implants are unable to be placed, and a second incision is needed when revision breast surgery is required. This technique is also not ideal for patients who are extremely thin or who have abdominal scars or hernias (see the images below).
Surgical dissection planes
Implants can be placed either subglandular, submuscular (underneath the pectoralis muscle), or in a dual plane with the superior part of the implant being covered by muscle and the inferior part under the gland.
Subglandular (prepectoral) augmentation does an excellent job of restoring breast shape and, compared to subpectoral dissection, may be a more powerful tool to correct minor breast ptosis. The disadvantage is that, in patients with little breast tissue or soft tissue cover, a higher incidence of visualization of the external contour and rippling of the implant may occur.
Submuscular (subpectoral) augmentation carries the advantage of lower capsular contracture rates and thicker soft tissue coverage to minimize the appearance of ripples. The down side is that patients who have well-developed pectoralis muscles may show animation ("dancing") of the implants upon muscle flexion. The implant can also ride high or migrate laterally over time.
The dual plane technique combines the advantages of these 2 dissection methods. Soft tissue coverage is improved at the superior pole of the breast, with an associated low contracture rate, but less of a problem with implant animation and the "double bubble" deformity that occurs when the gland slides inferiorly off of the implant (see the image below).
Follow-up / Monitoring
Breast implants are not lifetime devices, but most companies guarantee them for 10 years in case of rupture. Saline implant rupture is often more easily detected on physical examination than silicone implant rupture. Therefore, the FDA recommends that women with silicone gel implants get breast imaging with MRI to detect silent rupture three years after implantation and every other year after that. With saline implants, patients should proceed with their recommended mammography protocol for breast cancer screening. Moreover, they can develop capsular contracture over time and should return to the plastic surgeon regarding any concerns or questions regarding this.
With capsular contracture, a shell develops around the breast implant as healing occurs and, over time, it may become firm and even painful. The Baker scale is a grading system from 1 to 4, as follows.
Grade 1 - Soft breast in which the implant and capsule are not noticeable
Grade 2 - Minimally palpable implant and capsule
Grade 3 - Firm breast and capsule in which the implant can be palpated and distortion might be seen
Grade 4 - Firm, painful, and tender breast with significant visible breast distortion
See previous sections for more specific information related to breast implant techniques and types and their effects on capsular contracture.
Hematoma is a blood collection within the breast that often causes localized swelling and pain necessitates evacuation. This was reported to occur at a rate of anywhere from 3% in a study of 600 breast augmentations  to 0.9% of implants in a review of 3474 breasts.  The incidence of this problem is not associated with any particular surgical approach, patient characteristic, or implant type.
Seroma refers to a thin fluid collection around the implant. These usually resolve by themselves in a few days. When they do not, they can be aspirated under ultrasound guidance, but this procedure can carry a risk of damaging the implant. Closed suction drains should be used when implants are placed in conjunction with acellular dermal matrix as the hematoma rate is significantly greater in this setting.
Seromas rarely occur more than 1 year postoperatively (in 0.1% of cases).  This is noticeable by asymmetric breast swelling and may be due to mechanical friction between prosthesis and capsule or implant biofilm formation. This can also occur in the setting of infection, so fluid should be aspirated under ultrasound guidance and sent for culture. In a patient with a history of breast cancer, the appearance of a late seroma should raise particular concern for tumor recurrence, and fluid should be sent for cytologic analysis.
Wound infection is most commonly due to Staphylococcus aureus bacteria from the skin or lactiferous ducts. Infection can also be caused by more rare pathogens such as Candida albicans,Curvularia spp ,Aspergillus niger, mycobacteria, and Clostridium perfringens. One study reported the infection rate to be 2.2% in 899 breast augmentation cases. 
Changes in nipple sensation
Hyper and hyposensitivity of the nipple and breast can occur after breast implant placement. The incidence of this varies based on different literature series. For more information, please see the section on clinical implementation.
Saline implant rupture has been reported at 5–10% at 10 years. Silicone implants are often found to have been ruptured at the time of implant exchange for other reasons. One study determined from 478 explanted prostheses a 34% overall rupture rate: 33% for first-generation implants, 65% for second-generation implants, and 9% for third-generation implants.  In the case of suspected rupture, imaging studies can be performed to confirm this occurrence and the implant can subsequently be replaced.
Up to 1 out of every 5 women may have difficulty breastfeeding after implant-based augmentation. 
Current evidence does not support causality between breast implants and breast cancer or connective tissue diseases. Moreover, no evidence shows an increased risk of health problems to breast feeding children. In fact, one study demonstrated that the mean silicon level in cow’s milk and commercially available infant formulas was significantly higher than in silicone implant associated breast milk. 
Anaplastic large T-cell lymphoma
Anaplastic large T-cell lymphoma of the breast has been identified as a potential association with breast implants, without proof of causation.  (Only 27 cases were described up until 2011, and the incidence has been defined in women with or without breast implants as 0.1 per 100,000.  ) Fortunately, this disease is not only exceedingly rare but can often be treated with less complexity than primary breast cancer. Current recommended treatment for implant-associated anaplastic large T-cell lymphoma is capsulectomy and implant removal.
Pain, implant displacement, and implant rippling
Finally, as previously described in this article, pain, implant displacement and implant rippling can occur.