The placement of breast implants can be done either above or below the pectorals muscle. There are advantages and disadvantages to either implant pocket location and each patient must consider these carefully as either approach can be done in any patient.
Placing the implant below the muscle, known as subpectoral placement, is more universally done. It offers the advantage of a lower capsular contracture rate due to the muscular action of the overlying muscle. In addition it has better soft tissue implant coverage which avoids an unnatural implant transition in the upper pole of the breast.
But one disadvantage to being under the muscle is the aesthetic risk of an animation deformity. This means that as the pectoral muscle activates the contracture of the overlying muscle will cause the implant to undergo compression and show some lateral displacement. This is a well known subpectoral breast augmentation phenomenon that is most seen when raising one’s arms or deliberately flexing the muscle. It has a range of presentations and can be a minor and not a relevant aesthetic issue to one that is a major distraction and source of embarrassment for the patient.
The animation deformity occurs because the most inferior medial attachment of the pectorals muscle remains attached or unreleased with implant placement. It can also be affected by the size of the implant, the extent of the implant pocket creation, the muscular development of the patient, and the type of physical activity being performed.
When the animation deformity is significant it can be improved by additional muscular release. It is important for patients to realize that some amount of animation deformity is normal with submuscular breast implant placement and the implants can never sit under the muscle as passively as when they are placed above the muscle.
Dr. Barry Eppley