Breast reconstruction with synthetic implants was first described in the 1960s. It was initially a single staged placement of a permanent implant, performed at the time of mastectomy. It has now evolved into a multi-stage process consisting of expander placement with tissue expansion over several weeks to months, culminating in the exchange of the tissue expander for the permanent implant. This is a commonly-utilized option for selected patients undergoing mastectomy due to the relatively uncomplicated nature of the procedure which adds little extra time to the initial mastectomy. The expanders can also be placed after initial resection as a delayed repair, with the subsequent exchange for the permanent implant.
Pertinent anatomy for the reconstruction is similar to that of the oncologic breast surgery resection. The position of the inferior mammary fold (IMF) is of critical importance to the reconstructive surgeon as it is a reliable landmark for how far to extend the envelope into which the expander will be placed. This helps to define not only the vertical height and relative position of the reconstructed breast(s) but also the cleavage definition. Over dissection medially in the area of the sternum can cause symmastia, while improper placement in the vertical axis (or over-dissection inferiorly) will lead to vertical breast dystopia. 
Most patients are candidates for expanders and implants, and some patients will elect this option even if autologous tissue reconstruction is also possible. The ideal candidate is a thin female undergoing bilateral mastectomy or a thin female undergoing unilateral mastectomy with little to no ptosis of the contralateral breast, the latter indication is to facilitate the final symmetry between the breasts, as a ptotic breast is extremely challenging to recreate with an implant. Obese patients and patients with very large contralateral breasts may complicate the results of the expander and implant both in terms of final breast shape/definition and intraoperative placement. The expansion process may fail to obtain symmetry of the new breast pocket or fail to satisfactorily define the new breast owing to thick subcutaneous fat deposits.
The patient can often undergo the procedure immediately following the mastectomy, but can also choose a delayed repair in a subsequent surgery if they are unsure if they desire reconstruction, or if they wish to definitively know their need for any adjuvant radiation based on final pathologic results after mastectomy. The principal benefit of the immediate expansion is the avoidance of an additional general anesthetic. Additionally, it may be possible for the plastic surgeon and breast surgeon to collaborate on the best technique to retain as much native skin envelope as possible, though it must be emphasized the reconstruction can in no way compromise the oncologic safety of the mastectomy. The primary goal of the surgeon is the successful cure of the patient's breast cancer, reconstruction can always be re-addressed if surprises are encountered at the time of mastectomy. 
Careful patient selection for implant-based reconstruction needs to be undertaken, particularly in patients who may or will require adjuvant radiation therapy for their malignancy. Placement of a tissue expander in patients who are undergoing concurrent radiation may fail to expand, have poor wound healing and have poor projection. Complication rates can be as high as 60% for tissue expanders in radiated fields. 
Patients who are active smokers are at high risk of infection and poor wound healing. These patients need to undergo counseling for smoking cessation, and many surgeons will not offer reconstruction (particularly with expanders and implants, though potentially autologous tissue as well) to patients who are active smokers.
Many surgeons will have multiple shapes and sizes of implants available while performing the surgery. The final decision as to which implant to use may be based on the pocket that is achieved during the dissection, but this can often be estimated preoperatively with BMI, breast shape and position, and comprehensive physical examination. Lighted retractors may add a benefit during dissection, particularly in tight post-pectoral pockets.
The surgeon may benefit from assistance during the procedure, but this is up to the discretion of the surgeon.
Patients should be educated on all appropriate reconstructive options during their initial consultations, along with risks and benefits. Many patients may benefit from referral to survivorship group therapies prior to their procedure to gain insight on what to expect postoperatively, as well as individual patient experiences with various techniques.
Antibiotics should be given during the immediate preoperative period to decrease the risk of contamination of the skin flora into the wound.
The technique to create the submuscular pocket for expansion is similar regardless if the procedure is performed in a primary or delayed fashion. If performed during the initial mastectomy, the skin flaps are used to access the inferior-lateral border of the pectoralis major. Taking care to keep the inferior mammary fold intact, the surgeon dissects the pectoralis major muscle away from the chest wall, while maintaining its attachments to the lateral sternal border. Many surgeons will augment the subpectoral pocket with the use of an acellular dermal matrix such as Alloderm. This may aid in the speed of expansion and decreased pain, but this is based on anecdotal information rather than experimental data. A tissue expander is then placed into this subpectoral space, and the defect is closed over the device in a layered fashion. The tissue expanders have a port on the anterior side which is easily accessed in the clinic for subsequent serial inflation. A drain is then placed in the mastectomy pocket, and the skin closed. Tissue expansion occurs over weeks to months after the initial procedure with the intention to over-expand an envelope of tissue that will comfortably accommodate an implant. In the clinic setting, a magnetic marker can be used to identify the subcutaneous port. Under sterile conditions, the tissue is expanded with serial saline instillation into the port of the device. The patient is usually instructed to take over the counter NSAIDs to treat the pain associated with the expansion. Expansion may concurrently occur while the patient is undergoing chemotherapy; however, the patient should wait until their white blood cell count has normalized to undergo the exchange to a permanent implant. Once tissue expansion is complete, the tissue expander is planned to be exchanged for a permanent implant. A thorough discussion with the patient is imperative to discuss their different options regarding what type of implant is best for them, as many types are available and this may vary by location and surgeon experience and supply. 
Many different implants are available through the market. The implants are either smooth or textured, silicone gel or saline, and round or anatomically shaped. The benefits and risks of each should be discussed before proceeding. This portion of the procedure is straightforward; the previous incision is used to access the tissue expander, which is removed. If capsular contractures are present, a capsulectomy or capsulotomy can be performed at this time in order to achieve optimal symmetry. A disposable sizer may be used to identify the correct implant and achieve optimal base height, projection, and size to match the desired breast size (or the contralateral breast dimensions, if relevant). The implant of choice is carefully inserted into the pocket at this time under strict sterile technique, and the pocket is closed. Further detailing such as moving the inferior mammary fold, fat grafting, or even contralateral mastopexy/mammoplasty can be performed at this time to obtain symmetry between the breasts, though subsequent touch-up procedures to refine these elements may be required once the patient has healed.
Implants do not increase the incidence of breast cancer. They are radiopaque which can cause difficulty on mammogram, therefore, additional views are necessary. It may be necessary to follow the patient with other studies such as sonography and MRI. There have been recent studies investigating an increased risk of anaplastic large-cell lymphoma in patients having received macro-textured implants. While rare (incidence estimated at approximately 1/2,400 - 1/30,000), there appears to be a genuine increased risk and it is necessary to explain this to patients if such implants are to be used. This is an emerging indication for breast implant exchange.
Postoperative instructions and care are vital for successful outcomes. Patients should be instructed to avoid wearing bras with an underwire. Many surgeons will use surgical bras postoperatively to hold dressings in place and may augment this with a binding implant stabilizer to aid the position of the implant. Oral antibiotics are used at the discretion of the surgeon.
Complications of tissue expanders and implants are similar to those seen in cosmetic breast implant augmentation. Care must be taken intraoperatively to achieve hemostasis. Hematomas have high rates of infections and can increase the chance of capsular contracture. Prompt evacuation of hematomas must be performed once recognized, as this represents a true surgical emergency owing to the risk of loss of the overlying skin and soft-tissue envelope. Tissue expander and implant infection can lead to multiple procedures; while rare, this is potentially devastating requiring removal and ultimately repeat placement once the infection has resolved. Bleeding and infection are reported to occur at an incidence of 1% to 2%, respectively.Skin flap necrosis as a result of overly-aggressive inflation of tissue expanders can be devastating, and care must be taken to ensure adequate blood flow and not to be excessive when performing tissue expansion. Patient education is paramount, and any complaint of persistent or unusually severe pain, or of patient-reported color change to the overlying skin warrants immediate examination and possible partial deflation of the expander. Long-term complications are the most frequently encountered and can be very minor or very distressing, but typically do not jeopardize the ultimate success of the reconstruction. These include skin rippling, capsular contracture, infection, and implant rupture. Planned follow up with patients should be routine to monitor the implants for such delayed complications.
Capsular contractures are a fibrotic scar that forms around the implant as an extreme example of a foreign body reaction. It causes tightening of the implant, may displace its location, may make the breast feel abnormally firm, and can be painful. Contractures are graded based on the Baker scale. Baker Grade I is a normal, soft breast that appears to be in natural shape and size and therefore no discernable capsule is noted. Baker II is a slightly firm feeling implant with a normal appearance. Baker III is where the contracture causes the breast to firm and appears abnormal. In Baker IV, the breast is hard, distorted and painful. Surgical intervention should be considered for grade III and IV. Grade II to a Grade I contractures may still evolve, therefore special consideration should be given to these patients and their implants more frequently monitored. 
Recently, there has been a link with implants to T-cell Anaplastic Large Cell Lymphoma. Although most studies have been anecdotal, there seems to be linked to the textured implants because of the "salt-loss" technique causing chronic inflammation, bacterial biofilm or other causes that are unknown. This is an emerging indication for breast implant removal and research into etiology, specific risk factors, and treatment is ongoing. The incidence estimated at approximately 1/2,400 - 1/30,000 based on a series of over 3,000 patients published in 2020 from Memorial Sloan-Kettering. 
Breast cancer patients are a specialized population, and the reconstructive surgeon has a wide variety of options to help patients regain a sense of normalcy after their disfiguring surgery. Tissue expanders and breast implants play a key role in this reconstructive armamentarium but must be used in carefully selected patients. They are a relatively straightforward option for many patients, and their use has been widely studied and described, though they inherently require cooperative, compliant patients as well as multiple surgeries and office visits.
Breast reconstruction is often performed following breast cancer surgery. While the actual procedure is typically performed by a plastic surgeon, the patient is often followed by a nurse practitioner, physician assistant, or other members of the surgeon's clinical team. The primary care provider remains an essential member of this team and will likely see such patients in the perioperative period as well as long-term. Hence, it is important for these healthcare workers to be familiar with the potential complications of the procedure. Additionally, prior to the procedure, they should advise the patient regarding smoking cessation as well as overall health in preparation for one or more surgical procedures.
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