Tissue expansion is a surgical technique that allows the body to expand skin over time so that that tissue can be removed and used elsewhere on the body. Tissue expansion is an option used in plastic surgery for hair transplantation and breast reconstruction.

During the procedure, the surgeon makes in incision in the donor site area. The skin is separated from the underlying muscle and tissue forming a pocket. A small silicone implant is inserted into the pocket and the incision is closed. Immediately after the surgery or a short time later, a saline solution is flowed into the implant. Over the period of a few months, more of the saline solution is added to the implant allowing the body time for the surrounding skin and tissue to naturally expand and accommodate the growth in size. Once the desired amount of skin has grown, either a permanent implant is inserted, as for breast reconstruction, or the new skin can be removed and moved to a new area.