This is where the implant sits too laterally or under the armpit. It can happen when the surgeon makes the pocket too big, but it also happens with a regular pocket but a smooth implant that is too big that stretches out the pocket. It causes two problems really.
First, you lose your cleavage out of a bra because the implants are sitting too wide. And secondly, it often causes problem with exercise or when you lying down without a bra because the implants sit under your arm. Again, the treatment, like symmastia, is to use an internal bra technique to close off the lateral pocket. I run a suture down the lateral curve of the breasts to close off the pocket.
In the early stages after that operation, you can sometimes see some indentations in the skin on the side of the breast, but that usually settles down in time. In more severe or recurrent cases, I may use some mesh to help hold the implant in position.