Q: What can be done if I want to have a hair transplant and my scalp is very tight from prior surgeries? — R.R., Long Island, N.Y.

A: Follicular Unit Extraction is ideal in very tight scalps, provided that there is enough hair to extract without leaving the donor area too thin and provided that the follicles are not too distorted from the scarring.

With strip harvesting, undermining techniques may be helpful to close the wound edges once the strip is removed.

In undermining, the surgeon uses either a sharp instrument (scalpel) or blunt instrument (the dull edge of scissors) to separate the upper layers of the scalp (dermis and epidermis) from the lower part of the scalp (fascia). The hair transplant surgeon accomplishes this by spreading apart the fat layer of the skin or by cutting through scar tissue.

Undermining allows the upper layers of skin to literally slide over the lower layers and can significantly increase the ability to close a tight wound. However, if not done carefully, it may increase the risk of bleeding and injury to nerves and occasionally may damage hair follicles.

Undermining is usually used with a layered closure where the deeper tissues are brought together first with a layer of absorbable sutures before the surface of the skin is sutured closed with sutures that are removed.