During breast augmentation surgery, space is created in the breast for the implant to sit in. There are two options for patients with regards to where the pocket, or space, is made for their breast implant – under the muscle, called the ‘subpectoral’ or ‘dual plane’ pocket, and above the muscle, which is called the ‘subglandular’ or ‘prepectoral’ pocket.
Submuscular/Subpectoral/Dual Plane Pocket
When the space for the implant is made under the pectoralis major muscle, it is called the submuscular or dual-plane pocket. This pocket choice has many advantages. Since it is under the muscle, there is more natural tissue on top of the implant. This helps to provide more camouflage for the implant, leading to less visibility of the implant. This is especially important for women who have less breast tissue, to begin with, and for patients choosing saline implants. Since visibility of the implant can show as rippling, or ‘waviness’ of the implant surface, this pocket tends to decrease the chance of visible rippling.
Patients with implants placed under the muscle also have lower rates of capsular contracture which is firmness due to scarring around the implant. Having lower capsular contracture is important since scientific studies show that capsular contracture is the most common reason for a woman to undergo revision of her breast augmentation.
When the implant is under the muscle, the muscle can also help support the implant over time. As the breast ages, the breast tissue may become lower, but the implant often stays in the correct place. It is natural for breast tissue to lower with age, but since the implant is often still in the correct location under the muscle, the breast lift is often all that is needed to position the breast back in harmony with the implant. However, when the implant is on top of the muscle, the implant often drifts lower along with the breast tissue. In this case, the revision requires not only a breast lift but also a more complicated repositioning of the implant.
The downside to placing an implant under the muscle is a phenomenon called ‘dynamic motion’ or ‘animation deformity’. This occurs when the muscle is strongly contracted, and therefore puts pressure on the implant causing it to temporarily shift position, often upward and towards the side. This can vary from very mild with little movement to the very obvious movement of the implant. In some cases, it can cause discomfort. It is only visible during muscle contraction as the implant goes back to its normal appearance when the muscle activity stops. Revision surgery if severe may involve creating a new implant pocket on top of the muscle (subglandular pocket). Despite this possibility, Dr. Beber and many surgeons feel the advantages of the subpectoral/dual plane pocket, including less rippling, less implant visibility, and lower risk of capsular contracture, outweigh the disadvantages for many women.
The subglandular pocket is made in the space behind the breast tissue but on top of the muscle. It is also known as the ‘pre-pectoral’ space since it is in front of the muscle. Most surgeons agree that patients should have at least 2cm of breast tissue thickness in the upper pole of the breast if they are going to have their implants placed in the subglandular space. Since the implant is not camouflaged by the muscle, only the patient’s breast tissue is left to hide the implant edges and rippling. If the patient has very little breast tissue, it can make the rippling even more obvious. Research studies show capsular contracture occurs significantly more frequently for implants in the subglandular pocket compared to under the muscle (subpectoral). Some patients find the top edge of the implant is more obvious when the implant is on top of the muscle, making a more shelf-like rather than smooth slope appearance in the upper breast. This however also depends on how much breast tissue a patient has to hide the implant edge.
There are, however, certain situations where placing the implant on top of the muscle can have advantages. In bodybuilders, the ‘animation deformity’ that occurs during muscle contraction can be distracting during a competition. For some, it can limit the extremely heavy weights used by bodybuilders to create increasingly larger muscle groups. There are also certain breast shapes and anatomic conditions such as tuberous breasts and constricted breasts were placing the implant on top of the muscle allows the implant to push the lower pole out more effectively against overly constricted and tight tissue.
Ultimately, the decision about which pocket to use depends on a variety of factors, but Dr. Beber feels that in the majority of patients the advantages of putting the implant under the muscle outweigh the disadvantages.