String breast implants, also known as polypropylene implants, are not currently approved by the FDA. Although string breast implants were available for a very limited time several years ago, doctors no longer offer string breast implants in the United States.
Intended for individuals wishing to obtain extreme breast sizes, string breast implants continue to grow after they are surgically implanted, and can result in abnormally large breasts; string breast implants have resulted in the largest recorded increases in breast size due to surgical augmentation. The string breast implants were developed by Dr. Gerald W. Johnson, but were only available for a short time. String breast implants have been compared to “silly string” by patients who underwent breast augmentation that utilized string breast implants. The implants are made of a synthetic material called polypropylene, which causes the string breast implants to absorb fluids and expand. The absorbent nature of the implants means that women with string breast implants will experience almost continuous breast growth following her augmentation. Women who have received string breast implants are usually attempting to enhance their bustline to greatly exaggerated proportions, and most women with string breast implants work as adult entertainers.