"Bottoming out" of breast implants refers to the situation in which the implants move lower than we would like them to be. That might mean that they are too low for where the nipples are, they are too low in their position on the chest wall, or some combination of the two. Both of sides may be bottomed out, or only one of them could be.The main reason why this happens has to do with the anatomy and the way the tissues are structured in the part of the breast called the inframammary fold, where the breast mound attaches to the body wall at the bottom. In the fatty layer under the skin there are two compartments, or layers, with a layer of fascia, or supportive tissue, running between them. The uppermost layer, just under the skin, is firmer and has more support, while the deeper layer is flimsy and has very little support. When the supportive fibers attaching this fascia to the muscle underneath are cut or weakened, the implant is able to move downward behind that supportive fascia into the loose deep fatty layer. Thus, the implant sort of falls down behind the fatty layer along the muscle, and it appears too low.Many things can contribute to this situation, but in the end, the cause of bottoming out is the same: the implant has lost its lower support and is free to move downward. Thus, if the surgeon is repositioning the inframammary fold on purpose (sometimes we have to do that depending upon how your breasts looked preoperatively and the size of implants we are placing), or if it is weakened inadvertently, this can happen. Also, larger implants can put more stress on tissues, and this can also lead to bottoming out. Smooth implants are more likely to bottom out than textured implants because they can slide on the tissues more freely without friction. Also strong muscle activity with the pectoralis muscles when the implants are placed under the muscle can push down on the implants and cause bottoming out. This is why it is important to not only divide the attachment of the pectoralis muscle when placing implants underneath, but also it needs to be weakened a bit above the implant too in order to prevent unwanted muscle action. This is also why most surgeons recommend that patients with implants under the muscle refrain from exercises that intentionally build up the pectoralis muscles, like pushups or bench press.Bottoming out can certainly be controlled and for the most part avoided by proper pocket formation and proper suture support of the deep tissues, as well as selection of the proper implants. I hope this helps clarify the issue for you. Thanks for the great question!