Using this technique, each individual follicular unit (FU) is carefully created directly from the scalp, rather than from a strip of donor tissue that has been removed from the scalp (See FUT). The FU are excised from the scalp using a small, sharp cylindrical punch (generally 0.8mm to 1.2mm in diameter) which incises the skin surface around each hair follicle before they are carefully teased out manually with forceps.
The theoretical advantages and disadvantages of this technique are summarized in the table below. In general, FUE involves no suturing as well as less post-operative discomfort. But it has mostly gained popularity amongst those who often wish to wear their hair less than 2mm in length because – unlike the classical “strip” technique – it does not leave a linear scar in the donor area of a patient’s scalp. To accomplish this, FU removal is ideally performed in a random distribution within the safe donor region. After a single session or even multiple sessions of FUE, hair in the donor area appears to be slightly less dense than previously, but only upon close inspection.
One of the major potential drawbacks of FUE is the possible extraction of grafts that contain hair that is more likely to be lost over time. This potential problem stems from the mutual desire of both the physician and the patient to maximize the yield of transplanted FU in a single session. In general, the greater the number of FU transplanted using FUE, the more likely the session may include fewer permanent hairs and more temporary hairs that are destined to thin and ultimately disappear. Because increasing the yield of hair follicle harvesting during FUE requires selection of follicles from within a larger distribution of scalp donor area, a number of FU may be harvested from outside of the safe donor region. This zone is the region in which hair follicles will generally remain throughout a patient’s lifetime. It was established in 1994 after Walter P. Unger, MD examined 328 men over the age of 65 and found that 80% of patients under the age of 80 years retained hair within these boundaries (shaded). When transplanted, hair follicles will continue to grow as long as they would have in their original location. Therefore, for a long-lasting correction of hair loss, it is imperative to transplant only FU that will remain throughout a patient’s lifetime (i.e. from the safe donor zone).
Advocates of FUE mega sessions (over 2000 FU) often overlook this drawback to the technique if very large numbers of FU are to be transplanted. However, since the required distribution of extracted follicles must remain constant in order to retain a natural appearance of donor “thinning”, the increase in scalp area from which the FU are harvested must also increase in a linear fashion. Therefore, if a standard FUE session removed 1500 FU spaced every 3rd or 4th hair follicle apart within the safe donor zone, a 3000 FU session would require harvesting from twice that scalp area and a 4500 FU session would necessitate FU extraction from over three times that scalp area. The latter two sessions would clearly exceed the established safe boundaries and result in non-permanent FU transplantation.
Despite this limitation, there remain specific populations of patients who benefit from FUE. For example, patients who – as mentioned above – want to have no linear scars at any time and who do not have the requisite scalp laxity for effective donor strip extraction should opt for FUE. As the amount of tension required to close the scalp after a strip has been excised increases, the likelihood of a wider than average scar also grows. On the other hand, scalp laxity does not significantly impact the cosmetic recovery of the scalp after an FUE harvest.
Another group benefiting from FUE is the population of patients who have pre-existing scarring. Using this advanced technique to transplant FU directly into a scar, it is possible to camouflage or eliminate even a fine linear scar resulting from a prior surgery. For this reason as well as the aforementioned advantage of transplanting the largest percentage of permanent hairs via FUT, many surgeons believe that a combination of FUT (single donor strip harvesting) followed by an FUE session is optimal to achieve the largest number of safe, long-term FU from the donor area while minimizing or eliminating any resultant scarring (i.e. the best of both worlds).
Body-to-scalp FUE has been utilized when a patient is not deemed to have adequate hair density in the donor area of the scalp. However, this technique is still evolving, as transplanted body hair survival remains variable at best.
|No permanent linear scar||Fewer permanent hairs transplanted for equal number of hairs in larger (2000+ FU) sessions due to harvesting outside of the safe donor region|
|Comfortable healing process||Variable follicle transection (2-10%)|
|Decreased healing time||Small punctate scars|
|Fewer limits on post-op activity||Time consuming|
|Viable alternative if decreased scalp laxity||Costs more, labor, etc|
|Useful if limited number of grafts are needed (e.g. eyebrows)||Patient has to cut hair very short|
|Good of patient is a poor healer||Likely to bury grafts (folliculitis or cysts)|
|Ideal to repair donor scar that cannot be effectively excised||Scarring of donor area may make subsequent FUE sessions more difficult|
|Able to “cherry pick” most desirable size and caliber FU.||Limited candidates (not ideal for white or curly hair)|
|Good if patient prefers to wear their hair < 2 mm.||Grafts slightly more fragile and subject to trauma during placing since they often lack the protective dermis and fat of miscroscopically-dissected FUs|