Follicular unit extraction
Follicular unit extraction (FUE), also known as follicular transfer (FT), is one of two primary methods of obtaining follicular units, naturally occurring groups of one to four hairs, for hair transplantation. The other method is called strip harvesting. In FUE harvesting, individual follicular units are extracted directly from the hair restoration patient's donor area, ideally one at a time. This differs from strip-harvesting because, in strip harvesting, a strip of skin is removed from the patient and then dissected into many individual follicular units. The follicular units obtained by either method are the basic building blocks of follicular unit transplantation (FUT).
History and research
Follicular unit extraction (FUE) was first described by Masumi Inaba in Japan in 1988 who introduced the use of a 1-mm needle for extracting follicular units. FUE was successfully conducted on public patients by Dr Ray Woods in Australia, 1989 and was filmed for the 'Good Medicine' program for the first time in 1996. In 2002 it was first described in the medical literature by William R. Rassman and Robert M. Bernstein in their publication “Follicular Unit Extraction: Minimally Invasive Surgery for Hair Transplantation.”Robotic FUE devices were discussed at the 2007 meeting of the International Society of Hair Restoration Surgery (ISHRS), and research in robotic devices was presented by Dr. Miquen G. Canales and Dr. David Berman at the 2008 meeting of the ISHRS.Research was conducted by on the Artas system by Restoration Robotics in Mountain View, California and the Berman Skin Institute in Palo Alto and found that follicles could be removed individually at a rate of up to 1000 per hour through the use of 1-mm hollow needles. Despite showing evidence of improvements in transection rate from the prior year, the findings suggested transection at a rate of 6–15% was not low enough for general use in hair restoration procedures.
BHFUE or BHT is the Follicular Unit Extraction of body hair which is transplanted to the scalp. It was first tested and proven effective by Dr Ray Woods in 1998.  It was also documented that although the body hair would typically only grow up to 4cm, when transplanted to the scalp it could grow to 15cm.
There are still extremely few surgeons and practices which have mastered Follicular unit extraction because the procedure takes considerable time and expense to learn and to develop skills to a high standard. In recent years, the tools used for this approach have increased in complexity. Special Follicular extraction tools include the SAFE system, alphagraft, Neograft, and Artas system. These newer devices still have very little peer reviewed evidence based research in the medical literature. 
Follicular unit survival
The survival of follicular units upon extraction from the scalp is one of the key variables of successful hair transplantation. If follicular units are transected in the extraction process, there is a greater likelihood that they will not survive the transplant, and the hair transplant will fail. While FUT procures using strip-harvesting of follicular units typically guarantees a large number of non-transected follicular units, FUE procedures can, and often do, transect grafts, rendering them useless in a transplant. Significant efforts have been made to reduce the rate of transection in FUE procedures. The skill of the surgeon and his/her team, and the type of instrumentation used, are major factors in the ultimate yield and viability of the follicular units. Graft survival is also affected by time out of the scalp and exposure to air(especially in vacuum extraction devices). Different methods have been proposed to further improve graft survival affected by these later factors mainly by removing capture devices and adding/increasing time on ice. Many of the initial downsides of FUE by manual approach have been minimized with the introduction of newer motorized and computerized devices such as Neograft and ARTAS. These systems are still new with ongoing research, however no medline indexrd data has shown FUT vs FUE viability superiority.
FUE harvesting of grafts causes "pit" scarring, small, round, and typically white scars in the patient's donor area where the grafts have been removed. FUE scarring differs from scarring from strip harvesting in that the latter procedure produces a linear scar in the donor area where the strip of skin was removed. Both the pit scarring from FUE and linear scar from strip harvesting are often hard to detect when hair in the donor area is at a normal length and the extraction is performed by a skilled surgeon. While the outcome of the healing process, and thus the appearance of scar tissue, depends on several variables (including the type of extraction, the skill of the surgeon, and, in strip harvesting, the method of wound closure), in both FUE and FUT short cropped hair or a shaved head will typically reveal some scarring.
Comparisons with Follicular unit transplantation
Follicular unit extraction generally has a quicker patient recovery time and significantly lower post-operative discomfort than follicular unit transplantation (FUT). FUE provides an alternative to FUT when the scalp is too tight for a strip excision and enables a hair transplant surgeon to harvest finer hair from the nape of the neck to be used at the hairline or for eyebrows.
However, with FUE, the follicles are harvested from a much greater area of the donor zone compared to FUT, estimated to be eight times greater than that of traditional strip excision so requires patients to have hairs trimmed in a much larger donor area. As a result, the hair in the lower and upper parts of the donor area, where the grafts were taken from, may thin and this can make the donor scars visible. Follicles harvested from borderline areas of the donor region may not be truly “permanent,” so that over time, the transplanted hair may be lost.Maximum follicular unit graft yield is lower than with FUT and may result in greater follicular transection (damage). Due to the scarring and distortion of the donor scalp from FUE it makes subsequent sessions more difficult, and grafts are more fragile and subject to trauma during placing, since they often lack the protective dermis and fat of microscopically dissected grafts, ultimately which may result in poor growth. A problem of buried grafts can occur during the blunt phase of the three-step technique when the graft is pushed into fat and must be removed through a small incision. FUE can also be more expensive and take longer to perform than FUT, so grafts are usually out of the body longer, risking sub-optimal growth.
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