A very common myth about breast augmentation is that all breast implants should be placed under the chest (pectoralis) muscle.
Placing a breast implant under the pectoralis muscle has both advantages and disadvantages. As with most decisions we make, there are trade-offs for the benefits we may choose. The main advantage of placing a breast implant under the muscle comes from increasing the amount of tissue covering the implant, which makes the augmented breast look more natural.
A patient who is very thin with minimal breast tissue is greatly benefited by increasing the coverage of her implants. Because she has very little breast tissue, her breast will take the shape of the breast implant, since there is minimal breast tissue to give any other shape. Therefore, another advantage of placing the implant under the muscle in this patient would be the “softening” of the upper border of the implant so that the transition from her upper chest wall to the top of the implant will be softer and more sloped in appearance. The breast will not look so round or “grapefruit-like”, if the implant is placed under the muscle. In this patient, another advantage of subpectoral implant placement (under the muscle) is a decrease in the chance that any wrinkles in the implant will be felt due to the extra coverage the muscle tissue provides.
So what is the downside of placing a breast implant under the muscle?
Since a woman will continue to flex her pectoralis (chest) muscle, an implant, which is under the muscle, will move when the muscle moves. This movement will be downward and toward the outer border of the chest. Over time, cleavage is often lost due to the repetitive contraction or flexing of the muscles, which moves the implants apart. This increases the separation between the breasts. Most women do not find the movement of the implants or the increased space between them desirable.
Fortunately, it is possible to divide the lower border of the muscle and thin the upper border of the muscle in surgery and weaken the muscle slightly to decrease the intensity of this movement. Dr. Short routinely does this for her patients, as the implant movement can be very noticeable in a tank top or tight shirt. There will always be some movement however. In a woman with minimal breast tissue, the advantages outweigh the disadvantages of placing the implant in the subpectoral position. But in a woman with more breast tissue for coverage, the advantages are less and the tradeoffs of more movement with muscle flexion and decrease in cleavage are not balanced.
A breast implant placed above the muscle in the subglandular space (under the gland) will not move when the pectoralis muscle is flexed and cleavage will not be decreased over time. This patient is not likely to feel any wrinkles in the implant since she has plenty of breast tissue over the implant and she will naturally have a nice slope or transition from chest wall to implant because of her own breast tissue covering the implant. You can see that she receives very little benefit from placing the implant under the muscle and only experiences the disadvantages of this approach.
Dr. Short has prepared a video for her patients to watch prior to their consultation which summarizes the decisions to be made and demonstrates some examples visually.