Paradigm Shift from Linear Strip to Follicular Unit Excision in Hair Restoration Surgery

Abstract

Follicular unit excision (FUE) is a very effective and valuable modality for obtaining donor hair follicles using manual, motorized, or robotic devices to harvest individual donor follicular units in situ without a linear donor scar or visible scarring making it ideal for patients who wish to wear their hair short and hide signs of surgery. Over the past two decades, FUE has become increasingly popular, and the rising demand for FUE has driven the worldwide market size of hair restoration surgery (HRS) to an unprecedented height.

FUE has revolutionized the HRS industry and offers excellent cosmesis and high patient satisfaction. Unfortunately, a large part of the favorable appeal of FUE is due to false claims that it is “minimally invasive,” “scarless,” or “not even surgery.” Most patients opt-in for FUE due to these misconceptions, which are advertised by “black-market” clinics offering low-cost FUE surgery performed by amateur, nonprofessional technicians on unsuspected patients. The technique appears deceptively simple, and many neophyte surgeons falsely believe that the learning curve of FUE is short because the barrier of entry is low and no previous surgical skill is required. Nevertheless, injuries on grafts are extremely easy to occur since FUE is a blind technique and can be minimized only with excellent technique, which takes years to master.

FUE actually presents unique challenges for the surgeon and carries potential long-term permanent side effects if not performed properly. The surgeon must have a thorough understanding of the nuances of the FUE surgical technique to ensure consistent graft quality and favorable cosmesis of both donor and recipient areas. Efficient FUE requires dexterity, training, dedication, devotion, enthusiasm, cognitive clarity, scientific knowledge, experience, and an extended learning curve.

FUE is an invaluable addition to the armamentarium of a hair restoration surgeon but has to be judiciously performed.

Keywords

scarless FUE surgery - FUE graft transection - FUE megasessions - donor area depletion - FUE overhavesting - FUE graft injury - motor-FUE - FUE surgery delegation

Hair restoration surgery (HRS) is a surgical subspecialty with a shady reputation and probably not without reason. Results of older techniques or incorrect use of modern techniques have “stigmatized” countless patients since the 1960s and have defamed the HRS field to both the medical community and the public. The history of HRS is probably the most “sinful” in cosmetic surgery, with countless examples of poor surgical judgment, thoughtlessness, and dogmatism. Mistakes of the past in all aspects of HRS procedures have been dramatic, and acquiring knowledge through experience has been a slow, arduous process. Fortunately, some ambitious and ethical surgeons questioned the “dogmas” of early HRS techniques. These pioneers experimented with how to offer natural results and how to overcome surgical challenges by promoting the science of HRS and overthrowing older, obsolete, and illogical “techniques.”

Previous Paradigm Shifts in Hair Restoration Surgery

Surgical techniques evolve and improve with time since progress in technical instrumentation and growing experience both contribute to the increase of the effectiveness of techniques. For decades, HRS has been a typical example of scientific dogmatism and “attaching to a wrong idea,” which impeded the evolution of surgical techniques. The previous two paradigm shifts in HRS were preceded by decades of scientific stagnation and millions of patients carrying “stigmata of prehistoric HRS techniques” ([Fig. 1]).

Fig. 1 (a, b) A typical patient with old punch grafts and signs of several scalp reductions, who has been wearing a hair prosthesis to cover the grafts. (c, d) Excessively flared, triangular hairline with unnatural multifollicular unit grafts (minigrafts) that looks artificial, “aggressive,” draws attention. (e) Donor area with “shotgun” or “birdshot” scarring from punch graft harvesting. (Reproduced with permission from Anastassakis[23].)

Besides the archetype “Punch Graft Technique,” other “alternative techniques,” such as scalp lifts, scalp reductions, and flaps, were also available until the early 1990s. These HRS techniques had emerged solely from the poor results of the punch graft technique, which allowed room for literally any “alternative technique.” However, the first step toward a meaningful advancement of HRS away from the punch grafts was extracting of a horizontal–ellipsoid strip of scalp skin from the occipital area and the surgical approximation of the wound edges.[1] After extraction, the strip graft was further dissected into smaller grafts, later called micrografts (partial follicular units [FUs]) and minigrafts (groups of >1 FU,[2] [Fig. 2]).

Fig. 2 (a) Schematic representation of the preparation of minigrafts and micrografts from the dissection of the strip graft. (1) Separation in vertical “filets,” (2) micrograft with one hair follicle, (3) micrograft with more than two hair follicles, often containing parts of >2 FUs, and (4) minigrafts include multiple FUs or multiple, partial FUs. (b) Micrografts were mostly partial FUs, and minigrafts contained multiple FUs or multiple partial FUs. (Reproduced with permission from Anastassakis[23].) FU, follicular unit.

This “Strip Excision Technique” (linear strip excision [LSE]) became the new “Gold Standard” and soon, the success and acceptance of mini/micrografting finally brought the “craze” for alopecia reduction, scalp lifts, and 4-mm punch grafting procedures to a halt. At last, an HRS technique was safe, relatively easy to learn, and produced a result popular with patients and surgeons alike[3] ([Fig. 3]).

Fig. 3 (a) The incision follows both the lines of Langer and the curvature of the skull. (b) When a 15-mm wide strip is excised, it will double in width due to elasticity, but (c) meticulous, tensionless suturing will result in excellent healing in 10 to 14 days. (d, e) Another LSE case immediately after wound suturing and at 12 days postop, right before suture removal. Even this imperceptible LSE scar is not acceptable by patients anymore.

LSE optimized the donor area's management and significantly improved the thickness and naturalness of HRS results. However, the recipient area still suffered cosmetically compared with natural hair growth: tufted hair, pitting, cobblestoning, and “see-through” complications were still the standard with mini- and micrografts.

Luckily, in the early 1990s, Dr. Bobby Limmer[4] and Bernstein et al.[5] reached a logical endpoint of decades of refinement of HRS techniques based upon the earlier histologic observation by Headington[6] who presented that hair do not grow singly but emerge from the scalp in natural groups called FUs. The underlying premise of the technique these pioneers suggested, eventually coined Follicular Unit Transplantation (FUT), was that the integrity of the intact, naturally occurring individual FU should be preserved during all steps of the procedure: the FU should neither be broken up into smaller units (older micrografts) nor merged into larger ones (older minigrafts) for reasons of economy of size and minimal trauma.[5] [7] By simply copying nature, transplanting natural FUs instead of “custom cut” grafts had numerous defining cosmetic advantages and was the end of the evolution of HRS regarding the type, size of grafts, the naturalness, and thickness of the final result on the recipient area[8] ([Fig. 4]).

Fig. 4 (a) Natural follicular units did not contain useless skin surface, the graft size and diameter are minimized, allowing less injury, higher density, and a natural result (Reproduced with permission from Anastassakis[23].) (b–g) Result of follicular unit excision on a stage 6 patient after on megasession with 4,000 FUs. The FUs were “cherry-picked” to have a high hair ratio, and overall, 11,300 hairs were included in these 4,000 FUs, offering an impressive result!

Not the End of the Road Yet!

The natural progression of every cosmetic surgical field should be improved cosmesis. Since the results in the recipient area became perfectly natural with the advent of FUT, the expectations of patients concerning the donor area progressively increased. Soon, patients started to consider that even the thinnest LSE scar crossing the back of the scalp was no longer “acceptable” regardless of the cosmesis of the recipient area ([Fig. 3d]). Most young LSE patients were annoyed by the cosmetic limitation of being unable to choose a very short haircut on the back and sides of the head. Patients with scars from previous LSE procedures, or the unlucky ones who would heal with a poor scar due to surgical misjudgment or idiosyncratic reasons, were devastated. Extracting grafts without the “cosmetic cost” of a linear scar became the new frontier, and pioneer surgeons took on the challenge. Soon, the follicular unit extraction (FUE) technique appeared, which involved using tiny circular punches to dissect and extract intact FUs in situ. Since 2017, the acronym of FUE describes the updated term “Follicular Unit Excision” which actually explains the two steps of the process: incision and extraction. Shortly, an unprecedented race started to master this new technique and to advance the field even further by refining techniques or inventing tools.

How It All Started

The technique that would later (2002) be coined as FUE by Rassman et al[9] was not exactly original; similar ideas had been tested during the 1970s and continued to evolve even during the first years of LSE. However, the exact historical perspective of the FUE technique goes beyond the scope of this paper. Rassman et al[9] published their invented FUE technique in a peer-reviewed medical journal in 2002 and described the procedure, advantages, and limitations in detail. They had actually evolved the older (1996) technique of Inaba[10] and rendered it more efficient, applicable to a large number of grafts within reasonable surgical time while maintaining high survival rates.[9] Rassman et al used a manual extraction device, which consisted of a handle with a custom 1-mm punch connected to it with adjustable depth control ([Fig. 5]). The punching device was placed directly over an individual FU, the punch was advanced with a rotating/pushing movement of the fingers and thumb, scoring through the dermis, and the partly mobilized FU was then gently pulled out with forceps ([Fig. 6]). The resulting cylindrical hole (approximately 1 mm in diameter) was left open and rapidly healed by secondary intention, producing an imperceptible circular scar ([Fig. 7]). This new technique promised the “holy grail” of HRS: natural and thick results in the recipient area and no visible scarring in the donor area. However, this simplistic description does not account for the multiple challenges the authors met and the myriad more that future FUE pioneers would soon face when trying to replicate and evolve the original technique. Doctors from across the globe immediately adopted the new “FUE procedure” and embarked on aggressive marketing campaigns without any training and without understanding the nuances. Retrospectively, FUE turned out to be immensely more challenging than anyone realized. Most would soon produce for many years what Rassman coined a “Follicular Holocaust” instead of superior results than LSE.[11]

Fig. 5 (a) A manual extraction device used for follicular unit excision similar to the one used by Rassman et al.[9] (b) The punch is connected to a handle, and the depth can be adjusted according to the length of the follicular unit.

Fig. 6 The sequence of steps the surgeon must repeat thousands of times during each follicular unit excision session is as follows: (a) punch alignment, centering, engagement, (b) accurate and controlled advancement. (c) With proper dissection, a graft usually elevates 0.5 to 1 mm and (d) can be extracted using one or (e, f) two forceps. (g) Extracted grafts are then collected and stored (Reproduced with permission from Anastassakis[23].)

Fig. 7 (a, c) Global and (b, d, e) macro-images of the donor area immediately after follicular unit excision harvesting and 72 hours later. Incisions are mostly fully healed already.

Everyone Seemed Like a Candidate

As explained, FUE was developed as a response to poor donor scar outcomes of LSE, and it was basically a reimagining of traditional 4-mm punch grafting but, this time, with tiny punches. Therefore, the primary rationale for using FUE is that a visible linear scar is avoided and that patients were promised they could wear their hair short. Additional proposed benefits were considerably less postoperative discomfort or pain,[12] [13] more rapid surgical recovery, no significant restrictions on a very active professional, personal, or social lifestyle, a possible increase in scalp donor capacity (areas superior and more anterior to the ears and the nape of the neck can be safely harvested), limitations imposed by scalp laxity are decreased, and expansion of the potential donor area to include body hair.[14]

In addition, young patients—typically at higher risk for a wider scar after LSE[15]—could benefit from HRS risk-free, patients with hair loss limited to small areas or those requiring inherently small sessions, such as eyebrows, eyelashes, mustache, and limited areas of alopecia other than androgenetic alopecia (AGA)[16] were happily joining as FUE candidates, as well as those who tend to heal with wide scars or have hyperelastic skin. Very importantly, patients with inadequate scalp after previous strip surgeries, those who wished to camouflage older scars by FU implantation without removing the previous scar[17] and patients with scars from any dermatologic conditions, trauma, or neurosurgical procedures[18] could find a solution with FUE!

Not Really Scarless

A linear incision is not created with FUE; instead, thousands of circular incisions are produced. These rapidly shrink and heal, leaving behind tiny circular scars that are hard to see except on very close inspection. However, contrary to popular belief (influenced by enthusiasm and fraudulent advertising), FUE is not a scarless technique but a scar-spreading technique. Scar tissue is produced, and it is actually several times larger in surface area than in LSE. Admittedly, punctuate FUE scars are of no practical concern and are aesthetically far less noticeable than a linear scar for most patients. What is extremely interesting during these two decades of FUE evolution is the change of the focus of both surgeons and patients to the donor area instead of the recipient area! With the FUE technique, the focus has been on the incisional aspect to minimize transection rates and enhance extraction speed. Hence, everybody seems to care about the punches, devices, and how the donor area looks after surgery instead of turning the spotlight on the reason the patient came in the first place: having thick and naturally growing hair in the bald areas.

Probably the Last Paradigm Shift

The emergence of a technique that promised minimal scar visibility, minimal pain, and expanded candidacy found a huge appeal among patients and new surgeons alike. It created a paradigm shift for the HRS industry, changing both the public's demand since it was promoted as minimally invasive surgery and the need for service providers to fulfill the requirements for this process. During the first decade of the FUE-era, a great deal of discussion by physicians, ancillary personnel, the public, and multiple media sources surfaced on the internet about the value of FUE versus LSE harvesting and vice versa. Sadly, many of the newer technique claims of “superiority” were more related to marketing and physician self-promotion rather than an actual scientific evaluation.[9] Numerous doctors were strongly motivated to promptly include this technology in their patient offerings. More and more patients wanted it, and more and more physicians felt compelled to deliver it.[9] However, unlike other new technologies in medicine and surgery, where large companies are involved in the research, development, education, and dissemination of the new technology, no such evolution occurred in the field of FUE. Doctors were left to figure out solutions to the problems of FUE failures on their own and on the heads of their patients. They did well, eventually, but only with great costs.

The Prerequisites and the Right Process

The logic of FUE is to use a circular punch to excise a column of tissue containing an intact FU and all layers of skin by releasing the fold of arrectores and severing the adherence of surrounding dermal collagen. The graft is then gently but still forcibly extracted ([Fig. 6]). In the previous sentence, “intact” is the keyword: the surgeon should go to every length to avoid any trauma to the harvested hair follicles, with transection or amputation being the most severe. The FU proved to be an extremely delicate structure vulnerable to several types of injury during the harvesting process, and a multitude of problems emerged, inherent in removing individual FUs with tiny punches while trying to avoid significant follicular transection or amputation.[9] Overall, to successfully extract FUE grafts, there are definite general steps: preparation, incision/scoring, extraction, and collection. Besides the preparation step, the surgeon is required to extract each graft and repeat this sequence thousands of times during each FUE session. Patients may prefer FUE over LSE; however, FUE harvesting is a tedious procedure that takes its toll on the surgeon's patience, energy levels, muscles, and enthusiasm.

Follicular Unit Excision Harvesting Proved Tougher than it Seemed

FUE surgery does not require general surgical skills or skills of LSE with suturing, which used to be a genuine barrier to entry. This lower barrier, both in terms of perceived need for surgical skills and no need for multiple surgical staff trained in laborious microscopic dissection resulted in an explosion of neophyte providers worldwide. The perceived wisdom of a less invasive and “easier” procedure initially overwhelmed the reality of the very long learning curve required to pursue skilled FUE donor harvesting.[19] Almost two decades since the time of that first publication on FUE, the innovative efforts of many devoted surgeons improved the techniques and technologies related to FUE, and the quality of the service, have substantially improved only lately. Today, it is generally accepted that successful FUE donor harvesting has crucial technical, surgical, and artistic prerequisites with zero tolerance to error.

First, Do No Harm!

Overall, leaving the FU unharmed during FUE harvesting is no easy task. The principal challenge in FUE is that since the punch introduction is blind, no visualization of the FU or the arrector muscle is possible. Natural FUs containing one to four hairs are narrowest at the surface, and they naturally splay apart in random, unpredictable directions and angles in deeper layers waiting to be transected by the diving punch[20] ([Fig. 8]). Also, keeping the punch perfectly oriented to the follicular angle is very tricky, and even minimal wiggling during the push and twist movement will transect one or more bulbs ([Fig. 9]).

Fig. 8 (a) Follicles show varying degrees of splay as they extend deeper. Orange dotted lines show how a punch width determined by follicular grouping at the skin surface would damage the two outer follicles. Black lines show how a larger punch would preserve the unit, albeit at the expense of a larger surface wound. (b) FUs with two and three hair harvested from a patient with wavy hair showing various degrees of natural splaying. (Reproduced with permission from Anastassakis[23].)

Fig. 9 Internal–external hair angle is the difference between the external and internal average angle of follicles within a follicular unit. (Reproduced with permission from Anastassakis[23].)

Another equally vital challenge in FUE donor harvesting is the variability of the donor area. The viscoelastic properties of the skin impart biomechanical properties similar to the elastic properties of solids and viscous properties of fluids, contributing to the unpredictability of donor harvesting since skin soft tissue is composed of layers with different modulus and elastoplastic properties.[19] The interaction of the punch and tissue exerts multiple opposing forces, such as friction, torque, tangential force, axial force, oscillating force, etc., that can cause subluxation, overheating, or other types of injury to the FU are described in detail elsewhere.[21] The patient-to-patient variations in the epidermis, dermal–epidermal junction, and subcutaneous tissue contribute to the challenges of donor harvesting and achieving minimal follicular transection rates (FTRs).[19] Since the fine details of the technique will vary among experts (and patients), the principles of proper FUE donor harvesting technique are discussed elsewhere.[22] [23]

How Things have Changed

The innovative efforts of many devoted surgeons improved the techniques, technologies, and tools related to FUE, and the quality of the service has substantially upgraded since 2002. Today, using a variety of FUE approaches currently available, practically all patients can be successfully harvested.[24] Yet, it has been a long, arduous ride for both surgeons and patients who both experienced failures while doctors learned to adapt their techniques one step and one patient at a time.

Gradually, most surgeons switched from manual handles to motorized devices. Soon, the rate of harvesting grafts increased by manifolds, but surgeons realized that it required better control and dexterity as compared with manual punching. FUE device manufacturers, such as the Surgically Advanced Follicular Extraction (S.A.F.E.)[25] System (George Tiemann & Co, Hauppauge, New York), Powered Cole Isolation Device (Cole Instruments, Alpharetta, GA), WAW (Devroye Instruments, Brussels, Belgium), and Mamba device (Trivellini Tech), designed a variety of automated devices to speed up the process and reduce transection rates, which can be broadly divided into two groups: rotating and oscillating. In the latter case, the punch does not rotate in one direction but rather oscillates back and forth, mimicking the manual punch. More advanced devices incorporate programmable, multifunction controls of rotation, oscillation, vibration for tissue separation, or a combination of these to facilitate and improve the FUE dissection process.[26] Some devices have suction to extract the grafts, such as the Neo-Graft (NeoGraft Solutions, Dallas, TX) and SmartGraft (Vision Medical, Glen Mills, PA) but may be prone to reduced survival rate of grafts due to desiccation injury from constant airflow.[27]

Concerning punches, two distinct schools of thought emerged during FUE development, differing in the type of punches used for harvesting: blunt and sharp dissection.

Jim Harris, MD, developed the blunt punch and named his approach the “S.A.F.E. technique.”[25] The other school of thought uses a sharp punch with a “stop” to limit the depth of penetration,[21] advocating that sharp punches minimize friction and thrust force that damage follicles. However, sharp versus blunt punches do not solve the dilemma. Several physical and technical factors affect punch cutting dynamics, tissue distortion, and graft injury: punch shape, diameter, tip shape, punch edge sharpness, location and diameter of dissecting edge, punch wall thickness, and punch metal type. Therefore, there has been an explosion in the variety of incisional techniques using sharp, serrated, nonserrated, dull, hybrid, trumpet punches, and other designs ([Fig. 10]). Punch design categories, engineering, punch incision geometry, and metallurgy are beyond the scope of this chapter and can be sourced elsewhere.[21] [25] [28]

Fig. 10 Punch cutting-edge styles: (a) titanium tip sharp punches, (b) a serrated punch, and (c) a flared punch. (d) The serrated punch cutting edge shows multiple cutting edges and different designs. (e) The sharp punch shows the different locations of the cutting edge: inside, middle, or outside. (Reproduced with permission from Anastassakis[23].)

Minimally Invasive? Not Really!

Walter Unger[29] correctly commented on the original FUE publication[9] that FUE involves a tremendous increase in the total length of incisions when compared with conventional LSE harvesting: if one were to remove 2,000 FUs with FUE using a punch with a diameter D = 1 mm, the wound length (perimeter) would involve incisions totaling 6,280 mm, that is, CFUE ≈ 6.3 m. If LSE harvesting was employed from an average donor area (80 FUs/cm²), the wound length would be Cstrip = 400 mm = 0.43 m. Therefore, FUE's nearly 15-fold increase in incision length is hard to consider to be minimally invasive, as many proclaimed in the early years. The scar surface of each FUE incision (considering a 1-mm diameter punch and a perfectly vertical entry) would calculate EFUE = 1,570 mm², which actually equals a scar surface of 4 × 4 cm. In contrast, a typical 2-mm wide scar of the 180-mm LSE wound equals 360 mm², which is five times less for the same number of grafts.

Interestingly, by inserting the punch at a mean angle of 30 degrees, there is a 100% increase in the trauma that is caused by the punch[30] ([Fig. 11]). Nevertheless, although LSE harvesting combined with a trichophytic closure can have phenomenal results concerning minimal scarring, this is a benefit generally seen from the doctor's perspective. From the patient's point of view, FUE is a more minimally invasive and patient-friendly method,[31] even if it creates five- to ten-times more scarring than LSE!

Fig. 11 The “angle of attack” of the punch greatly influences the injury to the donor area impressively. The same 1-mm sharp punch will create an elliptical wound much bigger than its cross-section when angled. At 45, 30, and 20 degrees, the long axis of the elliptical wound is 41% (green), 100% (purple), and 192% (red) larger than the original punch diameter. In addition, inappropriate force, orientation, and direction of insertion of punch will eventually lead to wider incision wounds and graft transection. (Reproduced with permission from Anastassakis[23].)

Advantages and Disadvantages of Follicular Unit Excision

After more than two decades of cumulative experience, understanding of the pros and cons of FUE for the patient and surgeon is quite thorough. The following “objective pros and cons” of FUE take for granted that the technical skills of the physician are excellent, the tools are suitable, and the artistic perception is superb ([Table 1]). FUE, when not expertly performed by a professional, trained, and authorized provider (advisedly, a physician), will come at the grave cost of reduced survival, wasting of donor area reserves, and overharvesting.

Table 1 An objective comparison of linear strip excision versus follicular unit excision donor harvesting methods (Reproduced with permission from with permission from Anastassakis[23])

	Linear strip excision	Follicular unit excision
Postoperative donor area pain	Mild to moderate	Minimal
Duration of discomfort in the donor area	Between 2 days and a few weeks	Usually 1 day, but it can last for weeks if the area is overharvested
Percent of time the doctor operates on the patient	10 to 30%	80 to 90%
Stitches/staples required	Yes	No
Excessive bleeding during or after the procedure	Rare	No
Wearing a short hairstyle in the donor area	Rarely possible	Possible
Naturalness of the result	Yes, usually better density/coverage per session	Yes
Nerve damage, numbness, permanent pain	Rare	No
Healing time: donor area	On average 2 weeks until stitches are removed and fully healed at 6 to 12 months	Fully healed in 5 to 7 days
Tissue cutting/excising	Much less, but the wound heals into a linear scar, which can be perceptible	Significantly more wounding/scarring but spread out, and therefore less visible
Time until the next session	10 to 12 months	Next day: different area 6 months: same area
Period for complete healing of the recipient area	About 10 to 14 days	About 10 to –14 days
Transection rate	1 to 2% with an experienced surgeon and surgical team	Depends on the training and skill of the surgeon. Approximately 5 to 10% in expert hands; can be >70% in inexperienced hands
Type of grafts	Trimmed to the exact shape and size the surgeon wishes	Grafts are pulled out of the donor area and, most times, are thin and lack supportive tissue
Graft placement	Equally good with forceps or implanters	Implanters are preferred
Camouflage of linear donor scars	Difficult as a new scar is created	Excellent, one can even implant body hair grafts inside the scar
Number of grafts that can be harvested over a lifetime before evident thinning of the donor area	More	Less (3,000 FUs less the LSE)
Experience and skill of the surgeon	Most often high	It can be from high down to completely inexperienced neophyte surgeons or even a nonmedical operator
Quality of grafts	Excellent and predictable graft quality	Can be much lower depending on tools and technique, and will vary among patients
Permanence of harvested grafts	Excellent, all grafts are harvested from the “permanent” donor area	Only 25 to 30% of grafts are harvested from the “permanent” donor area
Exercise restriction	3 to 4 weeks for light exercise, 12 to 16 weeks for heavy weightlifting	2 weeks for any type of exercise
Amount of time after which the patient may return to work	2 to 3 days	Usually, the next day
Visible scarring with short hair	May occur	Very rare
Reaction to sutures	Rare	Never
Shaving of head	Not needed	Needed most of the times
Suitability for women with hair loss	Preferred technique	Women rarely opt in for FUE because of the need to trim the donor area
Possibility of megasessions (>3,000 grafts)	Yes, even up to 5,000 FUs for expert teams	Not advisable in 1 day
Type of hair where technique can be applied	All	Not advisable for kinky, curly, or white hair
Cost per graft	Lower	Higher
Fatigue of patient–surgeon	Less tiring	Particularly tiring for both the patient and the surgeon
Cost of instrumentation	Modest	Higher, especially with motorized devices
Cost of the surgical team	High	Minimal

Abbreviations: FUE, follicular unit excision; LSE, linear strip excision.

Advantages for the Surgeon

• The surgeon is safe that the patient will be more pleased with the image of the donor area compared with LSE.

• There is no need for a large assisting staff as an experienced surgeon alone or with one to two assistants can complete FUE cases requiring 1,500 to 2,000 FUs in a day.

• FUE does not require general surgical skills or LSE removal skills. However, artistic, diagnostic, and technical skills that take many years to develop are still necessary.

• Anyone can be a candidate for FUE, especially patients deemed further inoperable due to reduced laxity (which actually facilitates FUE) after several LSE procedures.

• The surgeon can “cherry-pick” grafts to achieve a significantly higher number of hairs per square centimeter, resulting in better coverage. Therefore, one can avoid too high grafting numbers per square centimeter that might backfire in terms of survival and offer a fuller look with lower and safer recipient area densities.

• Due to the small size of incisions, serious complications such as scalp necrosis are extremely infrequent, at least in experienced hands.[32]

• The cost of equipment can be low, especially if a manual punch is preferred over motorized systems.

• FUE can be used to truly repair the results of older techniques[33] instead of exchanging an old scar with a new, and hopefully, thinner scar, as is the situation in LSE scar repair.[34]

• Due to the minimal equipment and staff, the surgeon can easily travel and operate from different locations or countries, expanding the customer base significantly.

• Advertising FUE procedures is like a downhill run: patients respond extremely favorably to the seemingly less-invasive nature of the procedure compared with LSE, consider FUE a “newer” technique, and opt for surgery with minimal consulting.

• Finally, FUE may be combined with LSE in cases needing the highest numbers of grafts that normally would not be possible with FUE or LSE alone under “no-tension” donor closure.[35]

Advantages for the Patient

• When FUE is performed “lege artis” the patient can still keep their hair very short even after extensive harvesting.

• Postoperative discomfort is minimal.

• Surgical recovery is rapid, downtime is minimal, incisions are typically healed in just 3 to 5 days, and wounds are easily concealed.

• There are no significant restrictions on exercise, so patients with very active lifestyles may continue to exercise with minimal downtime.

• Limitations imposed by scalp laxity or multiple previous donor scars are decreased.

• Complications due to nerve and vessel injuries are very rare. Nevertheless, there have been reports of extensive anagen effluvium in the donor area.[19]

• Patients with extensive AGA may undergo two or three consecutive FUE sessions on consecutive days.

• Technician/assistant involvement in FUE can be minimal.

• FUs from other body areas may be transplanted, such as beard, chest, abdomen, back, hands, legs, genitals, etc.

Drawbacks for the Surgeon

• FUE requires the surgeon to learn an entirely new skill: FUE harvesting.

• The two most essential factors in the success of FUE are accuracy and speed, and both come with time, focus, and experience.

• FUE does not require previous surgical experience, but the learning curve is very long.

• FUE harvesting can be very time-consuming and needs more of the physician's time as compared with LSE harvesting.[36]

• FUE harvesting is a tedious procedure that takes its toll on the surgeon's patience, energy levels, muscles, and enthusiasm since the same actions are repeated thousands of times.

• Eye strain and fatigue set in after a few hours and can chronically tire the surgeon.

• With lengthy FUE sessions, the surgeon frequently experiences back and neck problems, which can progress to chronic conditions. The physician must pay close attention to the ergonomics and positioning to avoid long-term injury.

• Surgical time also includes the time spent by the surgeon to strategically select grafts to harvest to ensure that no area is overharvested.

• The surgeon must master more than one FUE technique and learn how to use more than one device and/or punch to customize each procedure for the individual patient.

• Reharvesting an area with FUE is exponentially more difficult than removing grafts from a virgin area.

• Diffuse thinning after excessive FUE harvesting is far worse cosmetically than a strip scar. Overharvesting will look like scalp disease, and it is impossible to camouflage.

Drawbacks for the Patient

• The most important drawback is that the number of grafts that can be safely harvested over one session and one's lifetime reduces total donor capacity when only the FUE technique is applied.[37]

• The main concern with FUE in most hands is the higher FTR compared with LSE.

• There are serious concerns about the fragility of the inherently skinnier FUE grafts compared with LSE grafts.[38]

• The FUE procedure is long and, hence, tiring for the patient.[39]

• The number of grafts extracted daily is limited, necessitating multiple sessions over several days.

• A higher cost per graft compared with LSE harvesting is the standard since the procedure is tiring, requires great experience and specialization, and is mostly performed by the surgeon.

• In FUE, the entire donor area must be shaved down to 1 mm (total shave), and some patients feel socially uncomfortable with a shaved look. However, long-hair FUE is increasingly popular among patients and surgeons alike and addresses this issue.

• The donor area is subjected to extensive microscopic devascularization injury, which can cumulate as permanently “thin” areas.

• African FUs or very curly/kinky hair with a powerful “character” below the skin has an increased risk of graft transection.

Controversies and Uncomfortable Truths of Follicular Unit Excision

FUE promises have been enticing for both patients and surgeons since the first moment. But, as in everything in life, things come at a cost. There are crucial considerations inherent to the FUE technique that if a surgeon wishes to extract high-quality FUE grafts, minimize transection, and offer reliable results, he/she must consider several factors.

Harvesting Rationale and Pattern

The essential premise is that donor area FUE scars (usually hypopigmented, pinpoint atrophic macules/dots) blend with remaining hair in a fashion that resembles an unharvested donor area so that surgery passes unnoticed. The surgeon is required to[40]

1. create the smallest scars possible: punch size, type, and angle of entry must be carefully selected on a patient-to-patient basis,

2. harvest grafts strategically and in a zigzag manner, skipping the neighboring FU to avoid a visible, linear 2 FU-area void of hair,

3. properly space excisions to ensure that there is hair emerging superior to the excision site to “cover” the extraction site, avoiding mottling and the risk of local devascularization, which could lead to scalp necrosis if it cumulates, and

4. widely distribute excision sites in a uniform distribution to avoid creating a “window” effect (central thinned area surrounded by denser hair).

Overall, the surgeon must homogenously “thin” the entire donor area to hide signs of surgery. If spread homogeneously throughout the donor area, white dots due to FUE harvesting produce the most aesthetic benefits.

All these require the area of harvesting to be generally five to six times the area of a donor strip for the equivalent number of grafts.[41] This leads to the following controversy of “unsafe” safe donor area (SDA) and “hair graft overharvesting.”

The Safe Donor Area Controversy

LSE surgeons harvest 100% of their grafts from within the actual SDA and can easily obtain more than 6,000 FUs in two or three sessions. To acquire a comparable quantity of grafts, surgeons performing FUE must only harvest far above and below the limits of the traditional, time-tested SDA. These are potential “danger zones” or strictly “unsafe zones” since they contain hair (weak or strong at that moment) that will probably be lost with time as it miniaturizes and becomes atrophic over time ([Fig. 12]). This inherently unavoidable protocol of artificial expansion of the harvesting area and the extraction of nonpermanent grafts creates an oxymoron[42]:

Fig. 12 (a) Safe versus unsafe areas to harvest are both very nicely depicted on this young patient with thin hair and low follicular density. (b) The red boxes outline the “extended” SDA used for FUE harvesting; the blue box is the “safest” SDA used in LSE harvesting. The more spread-out extraction protocol in FUE requires harvesting into “unsafe areas.” The long-term consequences of this widespread practice of “FUE-only surgeons” are worrisome. (Reproduced with permission from Anastassakis[23].) FUE, follicular unit excision; FUT, follicular unit transplantation; LSE, linear strip excision; SDA, safe donor area.

1. The surgeon leaves behind thousands of the best grafts inside the true SDA to provide coverage of adjacent scars.

2. Follicles harvested from beyond the limits of the true SDA will probably be lost in the future due to miniaturization and practically what one is offering is—at least partially—a temporary hair transplant[43] ([Fig. 13]).

Fig. 13 (a) Moth-eaten, thin donor area after one follicular unit excision session, which also resulted in minimal growth. (b) Notice the window effect with the thicker fringe of hair over the harvested area. (Reproduced with permission from Anastassakis[23].)

In addition, future balding may encroach into a harvested donor zone, and FUE scars may become visible, creating a new generation of unhappy hair transplant patients.[39] In addition, the surgeon must avoid producing zones of significantly lower density in hair “volume,” creating instead an “even thinning” of the donor area compared with natural density. This includes areas immediately adjacent to the balding margins[44] ([Fig. 13]). However, by preserving the evenness of density reduction, one risks future balding encroaching into the harvested donor areas and the potential visibility of donor scarring.[45]

Overall, the FUE surgeon is required to harvest from unpredictable donor areas that may miniaturize in the future and cannot sensibly guarantee that all harvested hair will remain in the recipient area for the whole patient's life. Therefore, many world-renowned surgeons who exclusively perform FUE will only accept patients for FUE megasessions under the premise that they will use finasteride indefinitely. Their rationale is that finasteride will “secure” the donor area and allow for adequate harvests from every part of it, even along the fringe zones. However, this rationale is risky as the efficacy of medications cannot be guaranteed for life.

The Plague of Overharvesting

Assessing the number of grafts that can be removed with FUE and the amount of trauma that can be inflicted on the donor area before coverage diminishes to a point where evidence of the procedure is obvious has not been entirely determined yet. No single algorithm integrates all the various factors to predict the minimum adequate donor area density after FUE, and therefore, surgical experience and judicious harvesting are crucial.

Sadly, the explosive worldwide popularity of FUE has contributed to a massive increase in patients suffering from donor area overharvesting (extracting too many grafts in one or several sessions). Severe cosmetic defects can range from minor degrees of visibly moth-eaten donor areas to almost complete donor alopecia ([Fig. 14]). Overharvesting is one of the factors that will lead to “donor area depletion.” Apart from removing too much hair mass from the donor area, other defining parameters leading to significant miniaturization of the donor hair and reducing coverage include the cumulative scar surface, the subclinical vascular damage, and “hidden” transections.[11] Notably, diffuse thinning after excessive FUE harvesting is far worse cosmetically than a strip scar: it will look like a disease of the scalp, and it is impossible to camouflage, unlike a linear scar that can be hidden by bangs above the scar. Longer hair can cover LSE scars, but the same long hair will make the overharvested FUE area look too “thin” and “see-through,” especially with the usual denser fringe at the balding border. Shorter hair might look less “see-through,” but then scars might show.

Fig. 14 (a–c) A typical “black-market” clinic's FUE megasession example with 5,000 to 6,000 grafts extracted in 1 day. Note the size of the grafts due to the use of a very large punch, making the area seem denser to the untrained eye. (d–f) The results of this practice are detrimental to the donor area. Notice the decimated donor area that even scalp micropigmentation failed to improve this terrible “pseudo-syphilitic” appearance.

In the same way, a poor LSE scar will force a patient to have longer donor hair, a patient with an overharvested FUE donor area will be forced to have either very short hair or a precise hair length that “balances” see-through and scar-showing. This is not what the patient expected when he opted for the—supposedly—“scarless” FUE method that would offer him cosmetic freedom. “Scarless” FUE is an intentional misnomer, nothing less than fraud. Predicting FUE harvest limits and avoiding overharvesting, some FUE experts have recommended guidelines that consider the initial “Hair Coverage Value”[46] based on hair shaft diameters and hair count per square centimeter. However, no metric or index can substitute for clinical judgment and thoughtfulness.[47]

Graft Injuries

The injury rate of FUE grafts is variable and entirely surgeon-dependent. Follicular transection is perhaps the most common injury observed with FUE. Keeping the transection/injury rate to a minimum depends primarily on the surgeon's skill (experience, eyesight, hand–eye coordination, ability to maneuver, etc.) and surgical technique (FUE extraction devices, punch type, punch size, speed of harvesting, etc.). The patient's factors include prior FUE scarring,[48] hair shaft exit angulation,[49] skin properties as described above, and others. Overall, the rate of transection/injury of grafts during FUE is fully operator-dependent, and details concerning the correct technique can be traced in the extensive literature.[50]

Follicular Unit Excision versus Linear Strip Excision Grafts

FUE grafts are forcibly extracted from the surrounding tissue and are typically skinnier, with less perifollicular tissue and minimal fat surrounding the bulbs. Therefore, many consider that FUE grafts are more “fragile” than LSE grafts and thus possess a higher risk of poor survival.[36] Graft quality is a significant component of FUE success, and the “gold standard” remains the microscopically slivered and created grafts obtained by LSE. Overall, it seems that with experience, superior technique, and proper instrumentation, FUE grafts are not inferior in terms of quality, and survival is comparable to LSE grafts.

Safety of Follicular Unit Excision Megasessions

FUE megasessions are lately presented as modern substitutes for LSE megasessions. Newer devices, better-designed punches, improved training, and cumulative experience—but mostly greed, ego, and ambition—have allowed surgeons to raise the bar on FUE megasessions significantly over 1,500 FUs in a day. Some entered a “race,” with heroic, albeit foolishly extensive, FUE megasessions of several thousands of grafts extracted in a single sitting without considering transection rates, missed attempts, and final growth. That is a very different story, making the safety of this practice extremely controversial.

Rassman et al have argued that there is a mathematical relationship determining a “safe FUE megasession,” that a human scalp can heal up to certain number of extracted grafts and that additional FUE harvesting is risky.[41] FUE donor removal patterns are markedly different from a 5,000-graft LSE surgery, which justifies the lower graft limit for an FUE megasession. As the number of harvested FUs increases and incisions are placed closer together in the limited space of the donor area, cumulative scalp microvasculature damage may appear. Unfortunately, the microvascular risks of FUE megasessions have been poorly documented. Vascular complications, such as (a) the appearance of focal areas of scalp necrosis and (b) increased donor area miniaturization in the remaining donor hair is far more common than reported. As the FUE megasession numbers rise, the injudicious harvesting of the finite donor supply results in decimated, see-through, moth-eaten, thin donor areas. These are typical of indifferent operators, most often “nameless” technicians operating on unsuspected patients in low-cost FUE destinations ([Fig. 14]).

Follicular Unit Excision Delegation and Other Ethical Considerations

The increased popularity of FUE is resulting mainly because of the advertisement done by the FUE device marketing companies and “black-market” clinics. The increased patient interest in FUE has led to an explosion in the delegation of the harvesting steps (or of the whole procedure) to nonphysicians that bear no responsibility for the damage they cause using substandard “working models”[51]:

1. The “Turnkey” model: An established doctor buys an FUE device from an instrument company, which also sends technicians to operate the device in his/her practice. The doctor “offers” FUE procedures under his name/brand but has zero or minimal knowledge of the procedure whatsoever. Automated and robotic devices may fall into this category of “fly-in, fly-out” model of roving technicians, and the unethical use of these devices is one of the reasons that have led to the commoditization of FUE.

2. The “Hair Farm” model: One physician, not necessarily a surgeon, supervises the various simultaneous surgeries done by the technicians. This is the new paradigm in heavily advertised FUE destinations around the world. The recent promotion of mechanized FUE appears to be encouraging technicians/assistants to perform the whole FUE procedure under “physician supervision.” The delegation limits the doctor's role to simply designing the hairline or welcoming the unsuspected patients in the clinic. In these facilities, unlicensed technicians will harvest from one patient more than 6,000 “grafts in one sitting,” using tiny punches of 0.6 mm to end up with less than 2,000 nonfully transected grafts that they transplant along with the more than 4,000 extracted pieces of scalp skin. The overall cosmetic result is typically poor, the donor area is totally wasted, and there is no possibility for future procedures due to donor depletion.[52] This model can have numerous severe consequences for the well-being and physical health of patients who fall prey to these fraudulent clinics ([Fig. 15]).

3. The “In-House” model: Staff members, already within an experienced clinic team, take over FUE harvesting or the entire procedure, often without proper training.

Fig. 15 Photographs from a “black-market” hair transplantation clinic in a Middle Eastern country. In this picture, more than 14 patients are simultaneously operated by nonmedical personnel under unscrupulous hygienic conditions. (Photo Courtesy of International Society of Hair Restoration Surgery, with permission, all rights reserved.)

Can This Last Paradigm Shift in Hair Restoration Surgery Go Wrong?

By all means, in an uncontrolled FUE environment, the reputation of the HRS field is now threatened by the rising tide of poor results delivered by unlicensed practitioners who operate on inappropriate surgical candidates, offer unrealistic promises, overharvest donor areas, and create unnatural hairlines.[53] [54] Rassman warns that surgeons will become less relevant to the actual technical delivery of HRS in the near future than they have been with traditional LSE surgery. He believes that future FUE teams will contain as few as two members, will use implanters and/or robotic devices that are more cost-effective, and will offer average size (<2,000 grafts) daily sessions of acceptable quality.[55] Of course, others disagree with this gloomy view and have a more optimistic vision for the future of the HRS field.[56]

Conclusion

FUE has revolutionized the HRS industry, and continuous progress in techniques and tools has allowed routine, excellent results from dedicated surgeons. The FUE technique offers excellent cosmesis and very high patient satisfaction. The technique seems deceptively simple, yet injuries on grafts are extremely easy to occur since FUE is a blind technique and can be minimized only with excellent technique, which takes years to master. Efficient FUE requires dexterity, training, dedication, devotion, enthusiasm, cognitive clarity, scientific knowledge, experience, and an extended learning curve. The explosive rise of “black-market” clinics that offer low-cost FUE surgery performed by amateur, nonprofessional technicians, is creating cosmetic problems and complications for unsuspected patients at an alarming rate. FUE is legally considered surgery and should only be performed by a licensed physician well-versed in the technical and aesthetic elements of HRS, with adequate training and expertise in all available HRS techniques. When all these prerequisites are met, the cosmetic results of FUE can easily compare and even outperform those of LSE in most patients without the burden of a donor linear scar. Apparently, sometimes you can have your cake and eat it, as long as it is done properly!

Conflict of Interest

None declared.

Acknowledgments

I express my thanks to Dr. Steven Gabel, MD, FACS, FISHRS.

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Publication History

Article published online:
13 December 2023