Because of the numerous advantages of putting breast implants under the pectoralis muscle, there are few, if any, situations where implants should be placed over the muscle. Prior to 1990, breast implants were routinely placed over the chest (pectoralis major) muscle. Since then, there had been a gradual shift towards under the muscle placement; so much so that subglandular (over the muscle) positioning is almost considered passé.
The first and possibly most significant advantage of submuscular (under the muscle) placement is a lower risk of capsular contracture which is firm, hard scar tissue forming around the implant. When this happens, the implant and the breast become harder than normal and can assume an abnormal shape. Capsular contractures can also become painful. There is a considerably lower risk of capsular contracture with implants under the muscle compared to over the muscle. Saline implants also have a slightly lower risk of formation of firm scar tissue than silicone gel breast implants.
The next advantage of implants under the muscle is that they tend to look and feel more natural because there is more natural tissue covering up the implant. The implant is less palpable and there is a lower likelihood of seeing or feeling rippling of the implant which can occur along the periphery of the prosthesis.
As a result of the support provided by the pectoralis muscle when implants are place underneath it, there is less of a tendency for the implant and the breast to sag over time. These breasts tend to be more gravity resistant than either natural breasts or those with implants placed on top of the muscle’s surface.
From a medical standpoint, possibly the most important advantage of implants placed under the muscle has to do with cancer detection. Breast implants placed on top of the muscle cause more problems with visualizing breast tissue on a mammogram and can, therefore, cause more interference with breast cancer detection.
Some disadvantages of subpectoral implants include a little more pain with surgery and motion of the implants with contraction of the chest muscle during exercise. These are greatly out-weighed by the advantages of under-the-muscle implants.
Everyone considering breast augmentation surgery should assume that, some day, they may desire to have their implants removed. If that happens, it is likely that many paatients will want to have a breast lift (mastopexy) performed at the same time to correct sagging due excess skin. Performing a breast lift when implants have been placed on top of the muscle carries a significant risk of necrosis (death, loss of) the nipple and areola. That risk is markedly reduced if the implants have been placed under the muscle because the blood supply to the nipple and areola is preserved to a much greater degree than when the implants are put on top of the muscle. Smoking and secondary smoke also increases the risk of loss of the nipple and areola at the time of a breast lift procedure.