The technique of tissue expansion, which was introduced by Radovan in the 1980 s and further developed by Argenta, paved the way for the use of implants for breast reconstruction in clinical practice. While implants had been used previously, they required a skin or myocutaneous flap to replace resected breast skin. Tissue expansion significantly increased the range of options in breast reconstruction, particularly for immediate reconstruction (see Chapter 11).
In principle, tissue expansion is indicated for all postmastectomy patients who have soft-tissue coverage of adequate quality, but insufficient quantity. Tissue expansion is less elaborate in terms of surgical technique than creating a skin or myocutaneous flap, and avoiding additional donor-site scarring or deformity is also an important factor for many patients.
However, using an expander requires a second intervention to restore breast contours and size. Before the second procedure, several office visits are needed for expander filling. These are disadvantages that many patients find inconvenient.
Despite the advantages of autologous reconstruction, tissue expansion is still regarded as a standard procedure in reconstructive surgery of the breast.
Several conditions need to be met for successful implant reconstruction. The contralateral breast should not be too large (a maximum of 300–400g), the thoracic skin should be undamaged and able to be mobilized, and the pectoralis muscle needs to have been preserved ( Fig. 6.1 ).
It is usually necessary to carry out the procedure in two steps. In the first stage, the tissue expander is implanted. In the second, after expansion of the soft-tissue cover, the expander is replaced by the definitive implant.
In rare circumstances, it may be possible to reconstruct a small-volume breast in a single operation using an abdominal advancement flap and an anatomical implant. If the contralateral breast is small and firm, volumes of up to about 250 mL can be reconstructed.
The more skin is present and the better the soft-tissue cover and reconstruction of the inframammary fold, the better the cosmetic result will be. An abdominal advancement flap can make it possible to recruit additional skin, but superior displacement of the flap causes bulging in the lateral portions of the skin, which are difficult to contour. In general, an expander implant is needed for a good cosmetic result.
In secondary breast reconstruction, complete muscular coverage of the expander is not mandatory as long as cutaneous soft-tissue conditions are stable and there is sufficient subcutaneous adipose tissue. After the mastectomy scar has been opened and the pectoralis muscle has been divided longitudinally, the muscle is dissected superiorly off the chest wall. This is usually possible with blunt dissection ( Fig. 6.3 ). Inferiorly, the origin of the pectoralis muscle is completely divided at the level of the fifth through seventh ribs, and a subcutaneous pocket is dissected on the chest wall or abdominal wall fascia ( Fig. 6.4 ). The lateral portion of the pectoralis is separated from the serratus. It is vital for the pectoralis fibers to be preserved adjacent to the sternum, in order to prevent medial displacement of the implant.
Expander implants ( Figs. 2.1–2.10 ) are now available in various shapes. Use of a single-chamber or dual-chamber system can help achieve targeted expansion in the lower breast pole. Sub-cutaneous placement of the expander in the lower portion of the breast, where a large amount of skin is needed for development of ptosis, allows a good degree of expansion.
It is essential to the success of delayed reconstruction that dissection extends inferiorly to the inframammary fold. This allows proper positioning of the expander and thus recruitment of the surrounding skin for reconstruction. Either the existing inframammary fold or preoperative markings are used for orientation.
The tissue expander that was introduced in the 1980 s had a smooth surface. Dislodgment or displacement was not uncommon, and sometimes contractures even occurred and prevented adequate tissue expansion. During the 1990 s, Maxwell developed a new generation of textured expanders that represented a further advance in the technique. With its precise pore size, the textured surface allows fibroblasts to grow in from the surrounding tissue. This prevents the displacement, especially in the cranial direction, that used to be common.
Although permanent expander implants are available, we prefer a two-stage surgical procedure, as it provides a better aesthetic outcome. A two-stage procedure is suitable for nearly all patients in whom implants are the preferred reconstruction method. Patient suitability is limited by the desired breast volume; for very large volumes, autologous tissue reconstruction is preferable. Maximum volumes for implant reconstructions are generally 400–500 mL.
If the skin cover is very thin, an attempt should be made to cover the expander in the lower breast pole with connective tissue from the chest wall or portions of the surrounding muscles (serratus anterior, rectus abdominis, external oblique) ( Fig. 6.1 ).
The choice of the expander implant is based on the size of the contralateral breast and measurements of the chest wall. The expander volume should provide expansion of at least 100–200 mL more than the contralateral breast. Expanders are typically 12–16 cm in diameter, with a volume of about 600 mL. Single-chamber and dual-chamber expanders are available, with either integrated or remote ports. The advantage of the integrated port is that there is no need to create an extra pocket for the port and no risk of rotation of the port after placement. A drawback is potential perforation of the expander if the needle is incorrectly inserted when it is being inflated. In any event, the textured surface of the implant is important, as it allows the expander to be integrated into the surrounding tissue, thus preventing displacement as it is filled.
The expander implant is emptied prior to insertion and then placed in the dissected submuscular site. After the muscle incision has been closed with several (absorbable) interrupted sutures, the expander can be initially filled with 100–200 mL of saline. Care should be taken not to cause excessive tension in the muscle layer. Closure of the skin wound must have an underlying muscle layer, with good perfusion in the base of the wound.
The wound cavity should be drained and perioperative prophylactic antibiotics administered. Antibiotic treatment for more than 5 days is not necessary if the viability of the muscle over-lying the implant is good.