If you have only a small amount of natural breast tissue then a lump may appear on the surface of your breast. This may happen fairly quickly after surgery after the swelling has subsided or it may take several years. This condition is called implant extrusion.
You may also experience implant extrusion if one or both of your implants have not positioned properly during surgery. This can also include incorrect dissection of an implant pocket which results in the implant being incorrectly positioned.
Implant extrusion usually occurs if part of the implant pushes its way through a weakness in your natural breast tissue covering the implant. Typically it feels like the corner of the implant is pressing against the undersurface of your breast skin. Although your implant does not have corners it does feel like this as I can state from my own experience of this condition.
Extrusion is typically at the sides of the breast. Again, extrusion is rare but if it does occur, surgery will probably be needed to correct it. You may need to weigh up the balance of correcting the extrusion or not as the surgery is likely to leave a visible scar on your breast at the point of the extrusion; is this worse than the severity of the extrusion itself?
Higher incidence of extrusion is found in women with overs as compared to those with unders. In particular, women with little natural breast tissue should consider under the muscle implants because of this. Although post operative recovery from unders is often longer and more painful, the extra muscle cover over the implant reduces the risk of implant extrusion.