Once breast implants are placed into the pocket created at the time of surgery, the body’s natural reaction is to form a scar capsule around them. This is an attempt of the immune system to ‘wall off’ what it sees as a foreign body. This scar capsule encloses the implant and keeps the overwhelming majority of any leaked silicone gel inside of the pocket.
Early Breast Implants
The first two generations of breast implants contained a silicone gel which was a very thin substance in an effort to make it feel as much as possible like natural breast tissue. The silicone shell which made up the implant surface was also very thin and allowed leakage of silicone gel outside of the implant even when the shell remained intact. This was known as silicone bleed. These early implants were actually called ‘low bleed’ implants. Although the majority of this silicone would remain contained within the scar capsule, a very small percentage of silicone would escape the capsule and migrate into lymph nodes under the arms. From there, it is possible for microscopic amounts of silicone to enter the circulatory system and get into other parts of the body such as the liver.
As silicone is one of the most common elements on the face of the earth, it is not uncommon for silicone to be found in very small amounts in the body even in individuals who do not have silicone implants. At this time, there is no known negative consequence of small quantities of silicone in the body which is one of the reasons that the FDA reapproved the use of silicone gel breast implants for the general population for breast augmentation in November 2006. The incidence of rheumatoid arthritis, lupus, fibromyalgia and scleroderma in patients with and without breast implants were found to be the same in numerous national and international studies.
Modern Silicone Gel Implants
Current generation silicone gel breast implants have a much more viscous internal gel as well as a significantly thicker shell than earlier generation breast implants. As a result, there is dramatically less silicone gel bleed outside of the shell and a much lower risk of silicone getting outside of the implant pocket. Although the new ‘gummy bear’ implants have an even thicker silicone gel, they are considerably firmer and more expensive than what most surgeons want to use for breast augmentation surgery.
Formation of thick or contracted scar tissue around breast implants causing them to become firm and misshapen is known as a capsular contracture. Although the exact cause of capsular contracture has not been fully elucidated, contributing factors include placement of the implants on top of the muscle and silicone implants. Early implants had a very high incidence of contracture and this was felt to be due to significant silicone bleed through the implant shell. As a result of a more viscous gel and thicker shells, the risk of capsular contracture has dropped significantly, approaching the low incidence of saline implants; especially when placed under the muscle.