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Michael Law MD Aesthetic Plastic Surgery

Sub-pectoral vs. submammary implant position

There are three approaches to breast implant pocket creation: subpectoral, subfascial and submammary. In the subpectoral approach, the pectoralis major muscle is elevated from the chest wall so that a portion of the implant resides behind the muscle. In the subfascial approach, only the outer fascia (connective tissue sheath) of the pec major is elevated, so that the pec major muscle lies behind the implant and the anterior pec major fascia lies on top of the implant. In the submammary approach, the pec major muscle and fascia is left undisturbed and the implant pocket is developed directly behind the breast (on top of the pec major).

Currently the subpectoral pocket is the most widely used approach, and it has consistently been the most popular approach as it affords the surgeon and the patient many potential advantages. The submammary approach is a distant second, and the subfascial approach has not gained significant popularity. In my opinion subfascial placement is really not that different, both in terms of postoperative appearance and long-term outcomes, from submammary placement. Before discussing the different approaches in detail, it is important to understand exactly what ‘subpectoral’ means.

‘Subpectoral’, ‘submuscular’ and ‘under the muscle’ are somewhat misleading terms, as in most cases the breast implant is only partially subpectoral. The anatomy of the pectoralis major muscle, when modified surgically as outlined below, is such that it is actually just the upper/medial half of the implant that is covered by the muscle, while the lower/lateral half of the implant is submammary. The pectoralis major thus provides an additional layer of tissue to conceal the implant in the most cosmetically significant area of the breast: the cleavage area and upper pole, sometimes referred to as the ‘social aspect’ of the breast as it is visible in some shirts, blouses, dresses and swimsuits.

In subpectoral augmentation it is important for the surgeon to release the inferior origin of the muscle across the lower pole of the breast, up the border of the sternum medially. The pec major would in most cases cover the majority of a breast implant if the inferior origin was not released, and if left intact the lower aspect of the pec major can create significant (and bizarre-looking) breast implant animation. When the inferior origin of the pec major is released, the inferior fibers retract upward (permanently), so that there is no muscle coverage of the most inferior aspect of the implant and therefore no significant breast implant animation.

‘Animation’ means that when the pec major contracts, the breast implant underneath it moves around – usually upward and outward towards the underarm area. You may have seen breast implant animation at the pool or at the gym, and if you have then you are well aware that it is NOT a cosmetically favorable outcome. Be sure that the surgeon who is performing your subpectoral augmentation can provide you assurance that you will not have obvious breast implant animation postoperatively.

As indicated above, a ‘subpectoral’ augmentation is not totally subpectoral and is in most cases really about half subpectoral. The upper half of the implant is subpectoral and the lower half is submammary. For this reason, a subpectoral pocket is often referred to as a ‘dual-plane’ pocket. In addition, the pec major can be released to varying degrees relative to the overlying breast. The most limited pec major dissection is referred to as ‘dual-plane I’: the pec major released but its inferior border is still below the level of the inferior border of the areola. Further separation of the pec major form the overlying breast can be performed such that the inferior margin of the pec major is at or just below nipple level (dual-plane II) or at the level of the superior border of the areola or higher (dual-plane III).

The more the pec major is released, the lower the likelihood of breast implant animation from pec major contraction, and the more a breast implant will tend to fill out the lower pole of the breast. My personal preference is at least dual-plane II dissection in most patients, as this maintains excellent upper pole / cleavage area implant coverage by the pec major, while minimizing the possibility of visible animation. Subpectoral position, even though it is really partial subpectoral position, is associated with the lowest risk of postoperative capsular contracture. Capsular contracture refers to thickening and tightening of the thin fibrous capsule which the body forms around any implanted medical device, which can make breast implants feel firm or even hard – and in advanced cases can distort breast implant shape and position.

In my opinion there is really only one ideal pocket position for breast implants in an elective cosmetic surgery patient: subpectoral, and specfically at least a dual-plane II muscle release. There are a number of very compelling reasons to place implants behind the pec major, some of which are outlined above, but the most compelling reason of all is the fact that radiologists report that an adequate mammogram is more easily accomplished when breast implants are sub-pectoral, compared to submammary or subfascial augmentation.

An American woman’s current lifetime risk of breast cancer is approximately 1 in 8 to 1 in 9, so the issue of breast cancer screening must be taken very seriously. Mammography is by no means a perfect screening study, but it is the standard of care at this point in time. The most sensitive and specific test for breast cancer is a contrast-enhanced MRI scan, and breast implants do not impair breast tissue visualization by MRI. And whether or not you have breast implants you should be performing monthly breast self-examination, and undergoing a yearly examination by your primary care MD.

The second most compelling reason to select subpectoral placement is cosmetic: implants that are placed on top of rather than below the pec major (submammary or subfascial pockets) tend to stand out in the upper pole of the breast, creating a rounded, convex and distinctly unnatural-appearing upper pole breast profile. With implants in a subpectoral position, the upper pole of the implant is flattened somewhat by the muscle, helping to create a smooth transition from the area in the upper chest where the breast begins, and a gradual slope towards the nipple that is not excessively rounded or convex.

In some patients who have a fuller breast volume preoperatively one may achieve an acceptable appearance with submammary placement – initially. The potential problem is that as breasts age, the fatty tissue often atrophies and breast tissue atrophies as well, and the area where this is most obvious is in the upper pole and cleavage area. So a submammary implant that was initially well-concealed may, after a number of years, become painfully obvious – in the form of visible implant folds and ripples in the upper pole and cleavage area.

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