Breast implants used in reconstruction cannot generally be placed directly in the space created by the removal of breast tissue. This is because an implant placed directly below the skin will generally not produce cosmetically desirable results and will be at high risk for eroding through the surgical incision, or through the skin itself.
Preparation of the mastectomy site for reconstruction with an implant therefore usually requires the additional insertion of one or both of these:
(A) A tissue expander is placed below the pectoralis muscle, the lower edge of which is first surgically separated from the underlying chest wall structures. As the expander is gradually inflated like a balloon—by injection with sterile fluid at regular intervals over a period of a few months—it stretches out the muscle and overlying skin to create enough space to accommodate an implant of the desired size. (B) During a second surgical procedure, the tissue expander is removed and a breast implant is placed in the pocket created below the stretched-out muscle. In many cases, the stretched muscle will cover only the upper portion of the implant. (C) Tissue expansion may be combined with the placement of a tissue matrix such as AlloDerm® to effect more complete coverage of the breast implant. Tissue matrix, attached to the lower edge of the pectoralis muscle and the chest wall, is shown spanning the lower portion of the implant.
Tissue expansion followed by implant placement is the most common method of implant-based breast reconstruction. This approach to breast reconstruction requires two separate surgical procedures.
In order to create space and prepare the chest for reconstruction using a breast implant, a tissue expander can be used to progressively stretch the muscles of the chest, and often the skin as well. An expander is like an adjustable balloon that is gradually inflated over a period of several months to make enough room to accommodate an implant behind the stretched-out muscle. Women who undergo expander/implant reconstructions typically visit the plastic surgeon every few weeks after surgery to have the expander filled by injection with sterile fluid; this process can be somewhat uncomfortable.
Because an expander cannot be fully inflated when it is first placed, a woman undergoing this method of reconstruction will not have a new breast right after her mastectomy surgery. Once ample expansion is achieved, another surgery will be required to remove the tissue expander and replace it with a breast implant.