Follicular unit extraction is one of the techniques for obtaining donor hair for hair transplantation. It is a technique that requires more skill from the physician hair restoration specialist and more cost from the patient than does strip harvesting (removal of a strip of scalp tissue bearing hundreds of follicular units). It is also a technique with potential benefits for the patient. For example, there is less donor-site scarring. If technical advances in FUE instruments make the procedure competitive with strip harvesting in the number of intact follicles that can be harvested per session, FUE may become a procedure of choice for more patients.
The Follicular Unit (FU) and FUE
Follicular unit (FU) is a term that describes how scalp hair normally grows. It grows in clusters of follicles, like little islands of one to four follicles on a plane of scalp skin. Each FU has a distinct make up of cells, nerves and blood vessels.
Strip harvesting of donor hair takes a strip of scalp tissue bearing hundreds of FUs for use in transplantation. FUE is different. It removes one FU at a time, targeting those that appear most likely to thrive and produce hair in a transplant recipient site.
In strip harvesting, a team of trained technicians removes follicles from the strip of harvested scalp tissue and prepares them for transplantation. In FUE, the physician removes follicular units one at a time from the donor site until there are enough for a transplant session.
Transection: A FUE Complication
When hair follicles in a FU are removed from a donor site and transplanted to a recipient site, the follicles should be healthy and intact, because they are more likely to thrive and produce hair. A problem for FUE from its beginning has been the transection or damage of follicles during the FUE procedure.
Why It Is Important to Keep a Hair Follicle Intact
A hair follicle is a complex. It is made up of layers of cells that provide specialized functions necessary for growth. Located under the follicle structure called “the bulge” is a permanent nest of stem cells that provide regenerative capacity.
The FUE surgical instrument is a hollow sharp punch that is designed to incise the skin around a FU from surrounding tissue. In manual FUE, the freed FU is extracted from its bed with forceps. The procedure sounds simple enough, but the apparent simplicity can be illusionary.
Transection occurs when the circular sharp blade of the hollow FUE punch fails to completely enclose the FU, and slices off a part of it. Transection can also occur when the FU is pulled apart when it is gripped and pulled with forceps. The damaged follicle in the FU may be useless for transplantation, or fail to thrive if transplanted.
In strip harvesting, a few transected follicles present no problem because the tissue strip contains hundreds of intact follicles.
When the number of transected follicles amounts to a substantial percentage of harvested FUs, additional cost may fall on the patient.
Thus, a patient who is considering FUE should ask for the physician’s FUE transection rate. A transection rate of 3% or lower can be considered good to excellent; a transection rate of more than 5% can be considered poor.