This is commonly known as “Muscle Animation”.
Muscle contraction of the pectoralis major muscle (chest wall muscle) may occasionally result in abnormal movement of breast implants when the implants are placed in a sub-muscular position.
The implant may deform, move in an abnormal manner or shift position with pectoralis major muscle contraction.
The pressure of the muscle on the implants may also cause the formation of a wide cleavage. If the contraction causes unacceptable implant movement, additional surgery may be performed to dissect additional muscle. Or it may be necessary to re-position the implants in a sub-glandular pocket.
Every woman with implants has some degree of rippling, and you will be able to feel it in areas with thin tissue coverage. You often cannot see it except in certain positions like bending forward. Rippling is more common with a softer implant and if there is less tissue cover, so if you are thin and/or have little natural breast tissue it will be more apparent.
Visible and palpable wrinkling of implants may occur and may cause cosmetic concerns in about 1 in 5 women. Some wrinkling is unavoidable and is related to the nature of breast implants.
Wrinkling relates to the shell composition and the nature and fill of the silicone gel within the implant.
It is less visible when an implant has a thicker breast tissue cover, when it is placed under the muscle, or when a smooth-walled implant (as opposed to a textured implant) is used.