Follicular unit transplantation

Follicular Unit Transplantation (FUT) is a hair restoration technique where a patient's hair is transplanted in naturally occurring groups of 1 to 4 hairs, called follicular units. Follicular units also contain sebaceous (oil) glands, nerves, a small muscle, and occasional fine vellus hairs. In Follicular Unit Transplantation these small units allow the surgeon to safely transplant thousands of grafts in a single session, which maximizes the cosmetic impact of the procedure.

FUT is considered an advance over older hair transplantation procedures that used larger grafts and often produced a pluggy, unnatural look. In a properly-performed follicular unit transplant, the results will mimic the way hair grows in nature and will be undetectable as a hair transplant.

History

In 1939 a Japanese dermatologist, Dr. Okuda, described the use of cars - grafting. Meaning the operation for the correction of skin on his head, eyebrows, eyelashes and whiskers, suffers from alopecia, the hair grafts using. In addition to Okuda, while in Japan, similar experiments were carried out more physicians, but their publication (Sasagva 1929, Tamura - 1943) in the Japanese magazines have remained unknown. The first hair transplant in the United States was performed by Dr. Norman Orentreich in the 1950s. He proposed the concept of "donor dominance" - the idea that grafts continue to show the characteristics of the donor site after they have been transplanted to a new site. This principle provides the basis for all hair transplant surgery. Although "donor dominance" ensured that transplanted hair will continue to grow, it did not ensure that the results would look natural.

Advancing Dr. Orentreich’s principle of “donor dominance”, Dr. Walter P. Unger first established the "Safe Donor Zone" in 1994 that helped shape surgeons’ understanding of the limitations of the donor area from which hair follicles area harvested.

The grafts used in the initial hair transplants were about the size of pencil erasers. These were obtained from the back of the scalp by punching out hair-bearing scalp tissue with a sharp, round instrument and then placing the grafts in holes made in the balding front-part of the scalp. The results of this punch-graft technique were often "pluggy" and unnatural and was referred to as a "doll's head" or "corn-row" look.

To improve upon the appearance of early procedures, doctors developed the technique of mini-micrografting; where the donor hair was obtained by removing multiple, thin strips of tissue from the back and sides of the scalp. Each strip was subsequently cut into different size grafts. The larger pieces, called mini-grafts, contained from 4 to 12 hairs, or more, and were used to create fullness. The smaller grafts of 1 to 3 hairs, called micro-grafts, were implanted at the hairline. Mini-micrografting gained popularity in the 1980s and became the standard hair transplant procedure through the mid-1990s. While it was an improvement over the older punch-graft techniques, the results were still not completely natural.

Follicular units were first described in the medical literature by Dr. John Headington in 1984. The FUT procedure has its roots in the single-strip harvesting method and microscopic graft dissection technique developed by Dr. Bobby Limmer in the late 1980s and published in 1994.

Dr. David Seager refined the dissection technique used in FUT in his 1996 paper on binocular stereoscopic microscopes.

Bernstein and Rassman formalized the principles that established the basis for FUT in their publication, "The Logic of Follicular Transplantation." The name of the procedure was formally changed from "Follicular Transplantation" to the more descriptive "Follicular Unit Transplantation" in 1998.

Key concepts in FUT

Follicular Unit Transplantation uses follicular units to accomplish a number of objectives critical to the hair restoration process:

Maximizing hair transplant growth

Since the follicular unit is a distinct anatomic and physiologic entity, preserving it intact during the graft dissection is felt to maximize growth. In FUT, after hair is removed from the back of the scalp in a single strip, stereo-microscopic dissection allows the individual follicular units to be removed from this strip without being damaged.

In the older mini-micrografting techniques, hair was harvested in multiple strips with the follicular units in each strip edge showing damage from the harvesting blades. The strips were then cut into smaller pieces, a process that would break up follicular units and risk additional damage to the follicles.

Ensuring the naturalness of hair transplant

Follicular Unit Transplantation enables the hair transplant to look natural both at the individual follicular unit level and in regards to the overall graft distribution. Since scalp hair normally grows in follicular units of 1 to 4 hairs, the exclusive use of these naturally-occurring units in FUT ensures that each graft will be identical to the surrounding follicular units. Thus, when the transplanted follicular units grow hair after a transplant, the overall results of the transplant will appear natural.

Additionally, by using individual follicular units, rather than larger grafts, the surgeon has a greater total number of grafts with which to work. This allows the surgeon to distribute the grafts more evenly over the scalp for a more natural overall distribution of hair.

Ease of surgical planning

The density of naturally-occurring follicular units in a normal scalp is relatively constant, measured at approximately 1 unit per mm². This helps in the planning of a hair transplant in two ways:

1. The hair transplant surgeon can accurately estimate the number of follicular grafts that can be obtained from dissecting a donor strip of a given size.
2. The same number of follicular units can be used to cover a specific size bald area regardless of the patient's actual hair density.

In patients with high hair density, there are usually a sufficient number of follicular units in the donor area to accomplish the patient's goals. However, in the patient with low hair density, a compromise must be made - and this is guided by the follicular unit constant. By transplanting a patient with low hair density using the same number and spacing of follicular units as in a patient with high density, the transplant surgeon will produce a thinner look, but will allow proper conservation of donor hair for future procedures.

Minimizing trauma to the scalp

The key to a natural appearing hair transplant is to have the hair emerge from perfectly normal skin, so minimizing trauma to the scalp is an important aspect of follicular unit transplantation. This can be accomplished by trimming away the excess tissue around the follicular units and then inserting them into small recipient sites on the patient's scalp.

Follicular units are relatively compact structures, but are surrounded by substantial amounts of non-hair bearing skin. This extra tissue can be removed without injuring the follicles, using stereo-microscopic dissection. These small, trimmed, follicular unit grafts can then be placed into tiny incisions in the patient's scalp; thereby minimizing damage to the scalp's connective tissue and blood supply. In contrast; the larger wounds produced by mini-micrografting and plug transplants caused cosmetic problems that included dimpling and pigment changes in the skin; depression or elevation of the grafts; and a thinned, shiny look to the scalp. These problems can be avoided using very small grafts and very small recipient wounds.

Another advantage of making small recipient wounds is the ability to create a "snug fit" for the follicular unit grafts. Unlike the punch grafts and some mini-grafting techniques; each of which removes a small bit of tissue in the recipient area; the trimmed follicular unit grafts used in FUT fit into small, needle-made incisions without any need for removing tissue. This preserves the elasticity of the scalp and holds the tiny grafts snugly in place. After surgery, the snug fit facilitates wound healing and helps to ensure that the grafts will get enough oxygen from the surrounding tissue in order to maximize their survival.

Ability to perform large hair transplant sessions

There are four reasons why the follicular unit transplantation procedure allows a hair transplant surgeon to transplant large numbers of grafts in each session:

1. The hair restoration can be completed quickly so that the patient has minimal interference with his/her lifestyle,
2. A larger number of grafts can compensate for the shedding that frequently accompanies a hair transplant, called telogen effluvium,
3. Using large numbers of grafts in each session preserves the donor supply by reducing the number of times incisions are made in the donor area,
4. Extracting large numbers of grafts provides sufficient 1- and 2-hair grafts to create a soft frontal hairline and enough 3- and 4- hair grafts to give the patient the fullest possible look.

FUT vs. FUE

In Follicular Unit Transplantation, hair has traditionally been harvested using a long, thin donor strip that is subsequently dissected into individual follicular units with the aid of special microscopes. In an alternative harvesting method, called Follicular Unit Extraction (FUE), individual follicular unit grafts can be removed directly from the back and sides of the scalp using a small, round, 1-mm punch-like instrument.

The advantage that the FUE method has over FUT is that FUE does not leave a linear donor scar, causes less bleeding, less post operative discomfort and requires no sutures. The early FUE procedure had a number of disadvantages including an increased risk of follicular damage in extraction which can lead to sub-optimal growth of the hair transplant. However due to advances in FUE more recent research indicates that FUE can produce results similar if not better than FUT.^{[citation needed]} The key determinant seems to be the experience of the hair transplant team and the quality of the extracted grafts.