Tissue Contraction—A New Paradigm in Breast Reconstruction

Hilton Becker, MD, FACS; Olga Zhadan, MD, MS

Disclosures

Plast Reconstr Surg Glob Open. 2018;6(7):e1865 

In This Article

Discussion

Tissue contraction is an integral part of wound healing. Wound contraction is brought about by myofibroblasts, which are derived from fibroblasts when gaining intracellular actin microfilaments. The actin microfilaments generate the force that results in matrix contraction.[9] Fibroblasts differentiate into myofibroblasts by a cell density–dependent mechanism. Masur et al.[10] concluded that absence of cell–cell contact is the proximate cause of myofibroblast differentiation. Myofibroblasts can differentiate back into fibroblasts with reestablishment of cell–cell contact.

Another key point in the fibroblast-myofibroblast conversion is the tissue tension. Fibroblasts experience tension in granulation tissue. Hinz et al.[11] revealed that fibroblasts seeded in the in vitro collagen lattice, which remained attached to the underlying surface, developed tension. These cells had myofibroblast phenotype. In the following in vivo study, the authors[12] showed that the mechano tension causes the generation of cytoplasmic stress fibers expressing alpha smooth muscle actin, a molecular marker of myofibroblasts.

Following injury to the skin, the dermis and subcutaneous tissue of the mastectomy skin flap will contract initially as a result of reduction in weight with the action of elastin fibers. Further contraction is a part of the healing process and continues until myofibroblasts associate with collagen extracellular matrix and return to the fibroblast phenotype. Contact of the exposed flap with the underlying tissues or the implant surface induces this transformation as well. If the implant is smaller than the pocket, contraction will occur until the space is obliterated.

Following modified radical mastectomies, it is necessary to expand the overlying muscle and remaining skin to create a breast mound. That is achieved using a tissue expander placed in the submuscular position. With the advent of skin-sparing mastectomies and prepectoral reconstruction, there is rarely a need for expansion.[13] In fact, in these cases, there is often an excess of skin. By allowing natural skin contraction to occur, skin excision is not required. Furthermore, skin contraction results in elevation and thickening of the skin flap, which is advantageous in terms of implant coverage, thus lowering the need for ADM. Skin contraction is commonly seen in cases in which a skin-sparing mastectomy is performed and no implant is placed. The loose skin flap contracts and starts adhering to the underlying muscle. The contraction continues until myofibroblasts of the flap convert back to fibroblasts induced by contact with the rigid muscle surface. Placing an underfilled adjustable implant beneath a skin flap prevents adhesion of the flap to the underlying muscle. The effect of delay is still achieved, and there is no further compromise to the skin flap. The surgeon is able to control the amount of contraction by varying the volume of the implant. Underfilling the implant will result in contraction of the skin pocket until the complete exposed surface is in contact with the implant. Excessive contraction is prevented by filling the implant to the desired volume. Skin contraction results in a mastopexy effect, thus reducing or even eliminating the need for skin excision. The low rate of rippling is attributable to the firmer thickened flap combined with fat injections.

The risk of skin flap necrosis or wound dehiscence is reduced by avoiding any additional pressure on the skin flap and incision. When skin flap necrosis occurs, the implant can be completely emptied, reducing all tension on the flaps, thus facilitating debridement and secondary closure. The complication rate following immediate breast reconstruction ranges between 5% and 40%. The use of an adjustable implant without ADM reduces the postoperative complication rate.[14] Although ADM may reduce capsular contracture, the complications of seroma and infection, and the cost are important considerations. In our study, prepectoral breast reconstruction was performed using the Spectrum-adjustable saline implant partially filled with air. The low-pressure, low-weight implant allowed the inherent ability of the skin to contract without undue pressure on the lower flap as seen with a saline-filled expander or gel implant, and thus avoiding the vascular compromise. The implant partially filled with air placed at the time of mastectomy functions as a spacer, which prevents the flap from adhering to the underlying muscle. The air spreads in the entire lumen instead of pooling in the lower pole as seen with a saline-filled implant (Figure 2A, Supplemental Digital Content Figure 3, 4). Flap adhesion to the chest wall is thus prevented. The need for delayed or delayed-immediate reconstruction is reduced.[15] The skin flap is thickened, thereby reducing the need for ADM. Also, the lower weight and smooth surface are more comfortable for patients who have higher immediate postoperative acceptance.

We have not seen capsular contracture in the studied group of patients. There may be factors associated with flap shrinkage that play a role. Longer follow-up is necessary for clarification.

The adjustable implant (Spectrum) has volume fill recommendations as dictated by the manufacturer. However, these volumes are not clinically related and not supported by clinical data. Our consent form indicates that exceeding the volumes is considered an off-label use. Exceeding manufacturer fill volumes has been previously published.[16]

A major advantage of underfilling the implant with air is that the position of the implant can be modified postoperatively. If the implant is sitting too low, the volume of air can be reduced and a strap applied inferiorly for 1–2 weeks (Figure 3). This will result in elevation of the implant, which can then subsequently be filled with saline. If the implant is sitting too high, the air is replaced with saline and an upper pressure strap applied that will lower the implant. This is as opposed to expanders with fixation patches, which cannot be repositioned postoperatively.

A textured integral valve expander gradually filled with saline would not function postoperatively as a smooth adjustable implant initially partially filled with air.

One of the potential downsides of our technique is premature skin contraction around an underfilled implant. Frequent clinical follow-up is therefore required to control the degree of pocket contraction around the implant.

Limitations of this study are the number of patients and length of follow-up. However, excellent results and low complication rate together with significant cost saving justify early publication of this techniques. A study reporting a larger cohort of patients and longer follow-up is currently underway.

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