You may have heard of someone's breast implants 'turning hard'. It is not the implants themselves that turn hard, of course; what has really happened is that the fibrous capsule around the implants has tightened and thickened, making the implants less mobile and causing them to feel firm (and eventually, in some cases, even 'hard'). The medical term for this phenomenon is 'capsular contracture'. It is a problem that is best managed by avoiding it altogether, and fortunately there are a number of things that can be done on the day of surgery to guard against it.
Any time a foreign object is implanted in the body, whether it is a pacemaker or a breast implant or an orthopedic device or anything else, the body responds by forming a thin, wispy, fibrous membrane around it. In most cases this membrane or 'capsule' stays thin and wispy, but in some cases over time the capsule may tighten around the implant and thicken, making the implant feel firm or even hard. In advanced stages the contracted capsule can even distort the shape and position of a breast implant. Capsular contracture can be treated, but it is a surgical treatment, so avoiding capsular contracture is all about avoiding another trip to the operating room.
Capsular contracture can occur on one or both sides, and while it can develop early (weeks) or late (years) after a breast augmentation surgery, in the vast majority of cases it is evident fairly early following the procedure. So the good news is that once you are six to 12 months out from your surgery, if your augmented breasts are soft and supple then they are likely to stay that way for the long term.
It is believed that capsular contracture is primarily a response to the presence of low-virulence or non-virulent bacteria (i.e. not the kind that generally produce an actual infection, with redness/tenderness/fever etc) that adhere to the implant surface on the day of surgery, and which over weeks and months following surgery stimulate the cells that make collagen (called fibroblasts) to make more collagen - thickening the capsule and stimulating it to contract and tighten around the implant. It is not an actual infection; there are no symptoms that this is going on, and taking antibiotics will not prevent the process or reverse it. The source of these non-virulent bacteria is thought to be the patient's skin, or the ductal systems of the breast that lead to the nipple, as both are normally colonized with bacteria.
Because plastic surgeons now have an understanding of some of the reasons why capsular contracture occurs, there are a number of measures that can be taken to significantly reduce the likelihood that it will happen following breast augmentation surgery.