CHAPTER 52 HAIR TRANSPLANTATION
CARLOS K. WESLEY, ROBIN H. UNGER, AND WALTER P. UNGER
Since initial reports on grafting human scalp hair were first made in Japanese literature in 1939, advancements in hair restoration surgery (HRS) have benefitted all patients, including both men in the early stages of hair loss and female patients. Incorporated in 1993, the International Society for Hair Restoration Surgery (ISHRS) now consists of over 1,000 members who performed approximately 279,381 HRS procedures in 2010, an increase of 11% over the previous 2 years.1
Modern day hair transplantation evolved over three distinct eras: the “plug” era, the transition period of progressively smaller unit minigrafting and micrografting, and the current period of follicular unit transplantation (FUT).2 This current method capitalizes on findings that human scalp hairs grow naturally in individual bundles, called follicular units (FUs), comprised of clusters of one to four follicles surrounded by concentric layers of collagen fibers.3 When performed properly, FUT consistently results in a cosmetic appearance indistinguishable from natural scalp hair growth (Figure 52.1). In addition to the more natural appearance of the transplanted follicles with FUT, the ratio of the donor-to-recipient area has effectively expanded. In the plug era this relationship was at best 1:1, but FUT now favors a ratio of 1:2 or 1:4, meaning 1 cm2 of donor scalp harvested may yield a sufficient number of FU (also referred to as grafts) to cover a 2 to 4 cm2 recipient area with adequate cosmetic density. Smaller, more superficial recipient sites can be spaced much more closely, while causing minimal damage to the preexisting hair in the recipient area. Despite these refinements, the unavoidable progression of hair loss over time and the limitation of donor hair for transplantation remain of paramount importance when determining the surface area and hair density that can reasonably be treated with hair transplant surgery.
INITIAL CONSULTATION AND EVALUATION
Patient candidacy is determined by a careful evaluation of the donor area’s capacity to effectively address the current and future areas affected by hair loss. In addition to providing information to the prospective patient and establishing a rapport with the patient, the physician should set realistic and prudent short- and long-term goals. Drawing from an examination of the patient’s hair phenotype, a thorough review of the patient’s family history of androgenetic alopecia (AGA) (including both the paternal and maternal lineages), and a familiarity with the progressive nature of male pattern baldness (MPB) and female pattern hair loss (FPHL), the physician can propose a surgical recipient pattern that will be appropriate even when having to “stand alone” at any future age. It is advisable to estimate the number of procedures or FUs the patient will likely have available over his or her lifetime based on the projected permanent donor fringe. Especially for young male patients, individual projections should be based on the worst possible scenario of MPB that can be realistically foreseen. This can help even young patients wanting to replicate their teenage level hairlines to modify their unrealistic expectations.
A thorough evaluation of the donor area is the critical initial step. The following elements should be considered: density of FUs per surface unit, number of hairs per FU, anagen–telogen ratio, diversity of hair caliber, color contrast between the hair and the scalp, hair texture (e.g., wave, curl, and frizz), and scalp laxity. While experienced hair restoration surgeons may be able to evaluate these characteristics with the naked eye, many practitioners prefer diagnostic tools to quantitatively assess the donor area (Table 52.1).
Screening technology that can help includes quantitative microscopic donor area measurements (e.g., Folliscope) as well as qualitative analysis of non-androgenetic forms of alopecia (e.g., PhotoFinder) that may benefit more from medical therapy (Figure 52.2). The Folliscope, capable of discerning between terminal and vellus hairs, is used by some practitioners to “rule out” patients who possess more than 20% miniaturized hairs within their donor area.4 Two separate measurements several weeks apart are required to differentiate between a hair that is miniaturized and one that is simply in early anagen (the growth phase in the hair cycle) and has only its thin, tapered edge protruding from the skin.
Once a patient’s surgical candidacy is determined, he or she is informed of the risks of the procedure. The authors emphasize three caveats: 1) postoperative edema that is minimal in most, but in approximately 2% of patients, may be severe enough to cause ecchymosis around the eyes; 2) scalp hypoesthesia resulting from severed sensory nerves during the processes of both donor harvest and recipient site creation, which may take 3 to 18 months to return to normal, and 3) telogen effluvium, or temporary hair thinning, that may be experienced by approximately 10% to 20% of male patients and 40% to 50% of female patients.5 If a patient is not emotionally prepared for this likelihood, they should not undergo HRS.
THE PREOPERATIVE PERIOD
Preoperative instructions include the discontinuation of herbal medications that may increase bleeding tendency, such as vitamin E and fish oil, 3 weeks prior to the date of surgery. Ten days prior to surgery, acetylsalicylic acid (ASA), or any drugs containing ASA that influence platelet activity, should be discontinued and the patient should abstain from alcohol consumption. The authors also recommend a twice-daily application of topical minoxidil 2% to 5% to the recipient area beginning 1 week prior to surgery due to the theoretical decreased likelihood of temporary hair loss.6 Patients with a relatively tight scalp are instructed how to massage their scalp during the final 4 weeks prior to surgery in order to increase scalp laxity within the donor area, thus enabling a wider strip harvest and a greater FU yield.7
The authors prescribe oral Cefdinir (300 mg) to be taken 1 hour prior to surgery. However, many surgeons avoid prophylactic antibiotics because they believe that the risk of adverse drug reaction outweighs the risk of infection. Written consent for the procedure, anesthesia, and photography must be obtained from the patient on the morning of the surgery.
SURGICAL PREPARATION AND ANESTHESIA
A comfortable operative experience greatly enhances a patient’s overall impression of the practice. Levels I and II sedation are commonly utilized. Preoperative sedation is often in the form of an oral benzodiazepine (diazepam 10 to 20 mg or lorazepam 2 mg) along with an analgesic (hydrocodone/acetaminophen 5/325 mg).
Photographic results can be optimized and reproduced when standardized. Generally, a ceiling light immediately behind the photographer with a uniformly bright background color enhances the viewing of the scalp by creating contrast, thus outlining the peripheral boundaries of the hair. High-definition video is often a more convincing media for viewers leery of misleading photographic tricks.
FIGURE 52.1. A 32-year-old man shown before (A) and 16 months after (B) treatment with 2,450 FU throughout the frontal third of his scalp. A 52-year-old female as seen before (C) and 14 months after treatment with 1,573 FU (D).
FIGURE 52.2. Folliscope evaluation for density comparison as well as total vellus and terminal hair number. This figure displays four digital images captured at 50-fold magnification and includes the area of 0.34 cm2 (ovals in box) in which quantitative analyses are performed. Calculations of hair density, growth rate, caliber, and spacing are illustrated in numerical format (right-hand panel).
The surgical design is drawn and the hairs in the donor area are trimmed to 2 to 3 mm in length. This hair length is chosen to facilitate correct angling of donor area incisions and to assist in determining directionality within the graft during implantation. The donor region is prepped with Betadine (povidone-iodine) prior to intravenous administration of an anti-anxiolytic (midazolam 2 mg, diazepam 5 mg) coupled with an analgesic, such as fentanyl (50 µg).
Local anesthesia of the donor site is achieved by creating a field block inferior to the donor region using 1% lidocaine HCl with epinephrine (1:100,000) followed by longer acting 0.25% to 0.5% bupivacaine HCl with epinephrine (1:100,000). This local ring block effectively anesthetizes the greater and lesser occipital nerves as well as the postauricular nerve. Further infiltration of 1:50,000 epinephrine is used not only to minimize diffusion of the anesthetic but also to enhance vasoconstriction, making surgical excision easier due to improved hemostasis. Additionally, sterile saline tumescence may be used to increase separation between the layer of hair follicle bulbs and the underlying nerve and vascular plexus within the deeper subcutaneous plane.
A field block anterior to the anticipated recipient area is then performed and reinforced in the same manner. Regional nerve blocks of the supraorbital and supratrochlear nerves are an alternative method of anesthesia for the recipient site.
THE DONOR SITE
Ultimately, the objective of donor area evaluation is to determine the area from which hair is most likely to be permanent and thus will ostensibly persist in the recipient area long after transplantation. To this end, the senior author conducted a study of 328 men aged 65 years or older in which areas containing at least 8 hairs per 4 mm diameter circle were measured.8 The dimensions established from this study represent the region of harvest that would be “safe” (i.e., the most hairs that would be most likely to persist) in approximately 80% of patients under the age of 80 years. This persisting region of the donor scalp was termed the “safe” donor area (SDA). These boundaries have since been modified for an alternative follicle-harvesting technique called follicular unit extraction (FUE), which will be discussed later in this chapter (Figure 52.3). Due to the less visible punctate scarring from this alternative technique, Cole’s FUE SDA is slightly expanded (203 cm2) and includes 14 subdivisions based on hair density.9
Although these accepted dimensions address the surface area of the donor area, they fall short of helping practitioners determine the quantity of “permanent” FU that may be transplanted over a patient’s lifetime. In order to provide guidelines regarding those limits, a survey of 39 of the world’s most experienced practitioners of HRS with a collective professional experience of nearly 1,000 years concluded that a 30-year-old male destined to develop Hamilton/Norwood type V or type VI MPB would most likely yield the numbers of FU as seen in Figure 52.4 based on the various degrees of donor hair density upon presentation.10 Respondents suggested that the aforementioned patient presenting with an average density donor area could yield a lifetime harvest of 6,404 or 5,393 FU when destined to develop MPB types V or VI, respectively.
Strip Excision. Strip excision is unquestionably the most common method for donor harvesting, used in roughly 88.5% of HRS cases.11,12 The most important tenets for strip harvesting include minimizing the amount of hair follicle transection as incisions are made; extracting donor strip widths with caution in order to minimize closing tension; and producing only a single scar regardless of the number of sessions performed on a single patient.
In addition to using magnification to help follow the angle and direction of hair shaft exit from the skin, minimal follicle transection can be achieved by using a tumescent solution at the dermal level prior to incising in order to increase the inter-FU distance and align the follicle shafts more perpendicularly to the skin surface. Follicular transection may be reduced below the current 10% to 15% average by using a skin hook technique (Figure 52.5) to facilitate separating the edges of incision.13 Alternatively, a tissue spreader comprised of a modified iconoclast instrument introduced into the superficial wound edge incision may serve the same purpose and may prove especially useful in gray or curly hair, which pose an added challenge to minimizing follicular trauma during the donor harvest.
FIGURE 52.3. A. The safe donor area (SDA) according to Alt. B. Unger’s safe donor area for 80% of patients under the age of 80 years, as determined from a study of 328 men aged 65 years or older. C and D. Cole’s FUE safe area. (Images courtesy of J. Devroye, M.D. and J. Cole, M.D. Redrawn from Unger WP, Shapiro R, Unger R, Unger M, eds. Hair Transplantation 5E. London and New York: Informa Healthcare; 2011.)
The most important factor in achieving optimal donor closure tension is a careful preoperative evaluation of scalp laxity. In the majority of patients, the authors excise a donor strip of 0.8 to 1.2 cm width from the densest portion of the SDA. An excessively wide strip can lead to excess tension, which may result in unsightly scars, temporary hair effluvium (short-term loss), or tissue ischemia. Many HRS practitioners assess scalp laxity by moving the donor tissue superiorly and inferiorly, or pinching it between their fingers, using clinical experience to gauge the laxity. Others rely on mechanical devices such as the laxometer prior to incising or the intraoperative tensionometer to estimate scalp laxity and closing tension, respectively.
If donor wound closure requires an unanticipated degree of tension, undermining skin edges may sometimes be coupled with a two-layered closure using interrupted absorbable sutures (3-0 or 4-0 vicryl or monocryl). Over the mastoid region, where excessive tension is most frequent, wedge-shaped sutures may also help relieve tension (Figure 52.6).14 This technique eases the work (W) required for closure more effectively than sutures placed perpendicular to the wound edge by increasing the distribution of force (F) along the wound edge. With F and wound edge displacement (d) being constant in the formula for work (W = Fd cos θ), the magnitude of work is reduced as the angle (θ) increases.
Excising a prior scar as a part of any new donor strip has numerous aesthetic advantages over extracting a new strip inferior or superior to it. Most importantly, the harvest is then always removed from the densest portion of the donor area to maximize both longevity of transplanted hair and the number of grafts per given strip width. Second, the new wound will not have its superior and inferior blood supply somewhat reduced because it is surrounded by virgin scalp tissue rather than bordered by previous scarring. Old scars also bind down the adjacent edge of the neighboring donor strip harvest, which may result in increased closing tension or a reduced available donor strip width. If a new strip is harvested superior (rather than inferior) to a linear scar from a previous surgery, lymphatic drainage will be compromised, leading to more severe and prolonged edema around the new wound. Compounding the probable less-optimal scar that results is the increased likelihood of telogen effluvium in the area between the old and new scar.
FIGURE 52.4. A total of 34 experts with over 900 years combined experience in hair restoration surgery responded to the question: “Keeping in mind that over the years, the hairs closest to the superior, inferior, and anterior borders of the fringe will be lost, how many FUcontaining very likely permanent hairs can be harvested from (a) a 30-year-old patient who you believe is destined to develop Norwood type V MPB and has: (1) higher than average hair density; (2) average hair density; (3) less than average hair density; (b) the same question but for a patient you believe is destined to evolve to type VI MPB.” While these data should not be viewed as dogmatic limitations, they may provide helpful guidelines when evaluating the lifetime donor yield of young Caucasian male patients.10
FIGURE 52.5. A. Two skin hooks for one assistant. B. Spreader inserted into scoring incision and (C) the spreader open, showing intact hair follicles at the edge of the wound. (Courtesy of D. Pathomvanich, M.D. and R. Haber, M.D. From Unger WP, Shapiro R, Unger R, Unger M, eds. Hair Transplantation 5E. London and New York; Informa Healthcare; 2011.)
FIGURE 52.6. A. The mastoid region, where scalp tension is often greatest, is the zone in which a wedge suture may be advantageous. A magnified panel illustrating how the placement of wedge sutures is slightly wider along the interior edge of the donor area. B. A block is pulled by a force (F) at an angle (y) to a horizontal vector (d). The work (W) required to pull the block along the horizontal plane (W = Fd cos y) is reduced as y increases. C. The work of a suture to bring two wound edges together is minimized as the placement of sutures along the inferior donor edge widens, increasing the angle (y) along the superior edge.
The final component of achieving nearly imperceptible donor area scarring is the closure technique. Most physicians prefer nylon sutures over staples due to patient comfort throughout the postoperative recovery process using either a single-layer or two-layer closure. A “trichophytic” closure may be used to provide further camouflage of the donor scar.15 By excising the epidermis from one edge of the donor wound prior to closing (approximately 1 mm wide and 1 mm deep so that the bulge area of the follicle is not affected), one row of hairs effectively lie beneath the healing wound and eventually grow through the resultant scar. This technique can be used in any surgery performed in hair-bearing tissue to help prevent the appearance of an alopecic linear scar. As in other fields of plastic surgery, bioactive acellular matrix products have been investigated in HRS donor wound closures. The results of using such substances are still unclear: one recent case report suggests that the resultant donor scar might be slightly wider and more erythematous, outweighing the benefit of the improved texture of the scar tissue.16
Follicular Unit Extraction (FUE). FUE is an alternative method of hair follicle harvesting that involves removal of individual FUs directly from the donor area one at a time, rather than from an excised strip that is subsequently dissected into FU (see below). Performed in approximately 11.5% of HRS procedures, this method holds the benefits of no linear scarring in the donor area as well as a more rapid and comfortable postoperative recovery for patients. Despite the overall increase in surface area of donor scarring with FUE compared with traditional strip harvests of large (1,000+ FU) sessions, when performed properly, the decreased visibility of scarring within the donor area may more often allow patients to wear their hair relatively short after undergoing FUE. FUE may also be utilized for beard and body hair follicle extraction as well as for removal of improperly placed grafts during corrective procedures of previous hair transplants.
Originally involving the use of a sharp 1-mm “cookie cutter”–like punch, hair follicles trimmed to 2 mm in length were extracted manually in a random distribution so as to avoid overharvesting any particular area, which may result in a “moth-eaten” appearance (Figure 52.7).17 Powered instruments for FUE have replaced manual punches by demonstrating increased extraction speed and efficiency.18 Increased speed, however, requires heightened attention to avoiding follicle transection or “decapitation” that may occur when a sharp punch is introduced at the improper angle.19 Variable hair characteristics such as follicle curvature, angle of exit from the skin, or splaying arrangement beneath the skin surface may further increase the challenge of avoiding graft transection in order to achieve intact hair follicle dissection. To minimize follicle transection, non-sharp motorized punches have been developed to perform “blunt” dissection of FU from the skin. Rather than cutting the deep segment of a follicle with an unforeseen curvature, a dull punch may push the follicle within the cylinder to reduce transection rates. Alternatively, a two-step manual process involving an initial sharp “scoring incision” at a 0.3- to 0.5-mm depth around the follicle followed by insertion of a blunt dissecting cylinder that reaches the full depth of the follicle (approximately 4 to 5 mm) enables full separation of the intact follicle from its native tissue prior to manual extraction using forceps. No matter what the technique employed is, a surgeon’s ability to properly position the punch according to the follicle’s angle of exit from the skin surface typically requires 5× to 6.5× magnification. In addition, as mentioned earlier, use of sterile saline tumescence increases predictability of hair follicle angle deep to the skin surface by making the follicles more erect and separates the follicle bulb from the underlying vascular and nerve plexus.
FIGURE 52.7. Punctate scarring from a previous FUE harvest performed by another surgeon can result in a “moth-eaten” appearance when FUs are harvested too close to one another or the punch used in larger than 1 mm. The dark outline indicates the borders of the limited region from which the FUs were harvested.
Follicle transection rates depend on the patient characteristics as well as the inner diameter of the punch. Among the field’s most experienced practitioners of FUE, transection rates range from 2% to 8.5% for the 1-mm punch and from 3% to 10% using the 0.75-mm punch.20 A 1-mm punch can extract an average graft of 2.5 hairs/graft, while a 0.75-mm punch yields approximately 2.1 hairs per graft. However, punches of 1 mm or larger can result in visually unacceptable donor area scarring.
There are two additional considerations in using FUE for follicular harvest. First, only every third or fourth FU can be removed from the SDA, thus reducing the total number of “most likely permanent” follicles available for transplantation. Second, the overall density in the donor area is reduced; as opposed to strip harvest in which both the number of hairs and the surface area is reduced, FUE removes hair and the donor site heals by secondary intention. This effectively leaves the surface area relatively unchanged, but reduces the number of hairs within the SDA. The long-term consequences of this technique may not be fully appreciated until patients experience the eventual thinning of the fringe hair, which naturally occurs over time. The authors share the sentiment of most practitioners in the field that combining FUE with strip harvest may provide patients with best long-term result. Maximizing graft yield from the SDA with multiple strip harvest procedures followed by a session of FUE when minimal or no remaining scalp laxity remains allows for a final session of transplanted grafts into both the remaining recipient areas and the resultant fine linear donor scar, thus optimizing the long-term appearance of both the recipient and donor areas.
GRAFT PREPARATION AND STORAGE
The stages of FU preparation during a classic FUT procedure are: 1) the initial donor strip harvest; 2) the “slivering” of the donor strip; and 3) the subsequent dissection of individual FU from the “slivers.” Each phase shares the common objective of increasing graft survival by minimizing follicle transection. To this end, the surgeon’s initial incision should be angled so that the blade passes parallel to the follicles. The excised donor strip should be fixed to a cutting board with steady lateral tension applied to sustain inter-follicular spacing and ease the “slivering” process. A size 15 bladed scalpel is used to slice sections of tissue 1 or 2 FU wide depending on the size of the grafts desired (akin to “slicing a loaf of bread”). The final preparation converts individual slivers into the appropriately sized grafts. Magnification (using a 6× lens with ample depth of field) and proper lighting (both overhead from a microscope and backlighting) are essential during graft preparation. A translucent horizontal cutting surface made of polyurethane allows for backlighting penetration.
The FU created from the naturally occurring hair groupings that exist in the donor area are markedly smaller than the original 4-mm punch grafts or multi-follicular unit (MFU) grafts referenced in prior editions of this textbook. Ultimately, the ideal “pear-shaped” graft possesses little or no surplus epidermis and retains an appropriate amount of protective dermis and subcutaneous adipose tissue around the follicle, the intact sebaceous glands, and the dermal papilla in order to reduce their sensitivity to traumatic handling, temperature changes, and graft desiccation (the main cause of poor graft survival).21 However, if more distal excess tissue is not sufficiently trimmed, the grafts may require more traumatic handling when placed into the recipient sites. The “pear shape” is generally more difficult to achieve when grafts are harvested via the FUE method because, after initial superficial incisions, the follicle is “pulled” from its native environment, thus causing the surrounding tissue to be stripped off the follicle (Figure 52.8). As a guideline, three- or four-haired FU should fit snuggly into recipient sites made with an 18G needle while 20G needle sites should easily accommodate one-haired FUs.
In addition to the above guidelines, which help improve graft survival, selection of the proper holding solution may also be significant. This has grown progressively more important as larger surgeries involving smaller grafts have become more common and “out –of-body” time has increased. Generally speaking, survival of transplanted grafts decreases about 1% per hour out of body with some studies indicating an 88% survival at 8 hours in chilled normal saline.22 To help counteract the effects of this extended time between harvest and implantation, three broad categories of commercially available holding solutions are considered as alternatives: 1) intravenous fluids (e.g., Plasmalyte A and Lactated Ringer’s); 2) culture media (DMEM, RPMI, and M199); and 3) hypothermic tissue-holding solutions (Viaspan, Celsior, Custodiol, and HypoThermosol). Characteristics assessed in these solutions include pH, osmotic balance, antioxidant capabilities, and nutrient support. Akin to organ transplantation, factors of negative influence include ischemia-induced hypoxemia and subsequent adenosine triphosphate depletion (resulting in subsequent apoptosis) as well as ischemia-reperfusion injury.
The events following graft implantation, specifically oxygenation and revascularization, are also believed to be critical in graft survival. For this reason, platelet-rich plasma (PRP) has been explored as a possible graft storage solution. Obtained from the patient’s blood and concentrated via a centrifugation process, PRP’s release of concentrated growth factors may augment graft survival and promote earlier growth and enhanced wound healing.23,24 This technique has been reported to have mixed results to date and requires further investigation before any conclusions can be drawn.
THE RECIPIENT SITE
Transplanting even the finest FUs does not ensure the creation of a natural-appearing recipient pattern unless the major anatomic landmarks, borders, and zones of normal hair-bearing scalp are well understood and effectively reproduced (Figure 52.9). With the increased demand for HRS among young adults in the early stages of MPB, one of the most important principles of hairline placement is “do not place a hairline too low.” The most anterior midline point of the frontal hairline should be somewhere in the zone in which the relatively vertical forehead gradually changes to the relatively horizontal anterior caudal scalp. 25 The more severe the ultimate MPB pattern is expected to eventually develop, the more superior this point should be. It should be joined in a gently arched line to two lateral points in the existing anterior temporal hairline or in a reconstructed supratemporal–parietal “hump” constructed with FU if it has been or is expected to be lost with the passage of time. When viewed laterally, the transplanted hairline should run more or less horizontal to the ground or tilt slightly superiorly (Figure 52.10).25
FIGURE 52.8. A. Grafts produced via FUE have less protective tissue surrounding the hair bulbs within them and may or may not result in a lower hair survival than that seen with (B) grafts that are microscopically produced from a strip. FUG, follicular unit grafting.
FIGURE 52.9. Common guidelines to proper placement of the midfrontal of the hairline include (A) a point on the curve of the forehead about ½ way between from the point where the horizontal plane of the scalp meets the vertical plane of the face, (B) 7 to 10 cm above the glabella. Major landmarks and zones of the hairline: C. top view; D. side view. (Courtesy of R. Shapiro, M.D. From Unger WP, Shapiro R, Unger R, Unger M, eds. Hair Transplantation 5E. London and New York: Informa Healthcare; 2011.)
FIGURE 52.10. Proper placement of the fronto-temporal angle in mild-to-moderate hair loss: Common rules include (i) draw a line from the lateral epicanthus of the eye to a point where it meets the remaining temporal hair; (ii) make sure the hairline does not slope down toward the ear but appears parallel or slopes upward. (Photo courtesy of R. Shapiro, M.D. From Unger WP, Shapiro R, Unger R, Unger M, eds. Hair Transplantation 5E. London and New York: Informa Healthcare; 2011.)
To create the illusion of a slightly lower hairline without expending too many FUs, some surgeons construct a “widow’s peak.” Throughout the hairline, the transition zone (the anterior 0.5 to 1 cm region) should contain both microirregularities (intermittent density clusters more noticeable under close examination than from a distance) and macroirregularities (protrusions along the path of the hairline that cause it to appear less linear when viewed from a distance). Generally, macroirregularities include one central mound and two lateral mounds.
It is generally not advisable to advance temporal points in young male patients who are likely to experience a progressive posterior recession of their temporal hair. Their limited donor reserve may be inadequate to address these future areas of loss if the transplanted hair is placed too far anteriorly (thus leaving an unnatural “island” of transplanted temporal hair). However, when the donor-to-recipient ratio allows, temporal points should be advanced no farther than to an intersection of two lines: one drawn from the tip of the nose, over the pupil to the anterior tip of the temporal point; and a second line drawn from the most anterior midpoint to the tragus.26
Ethnic background should also be considered when designing the hairline. Whereas Caucasians generally have doliocephalic, or ovoid, skulls East Asians tend to have brachycephalic, or rounded, skulls.27 As a result, the hairline design in East Asians is comparatively wider and flatter, with curved (rather than sharp) frontotemporal angles. The relatively coarse caliber of East Asian hair may make multi-hair FU more noticeable. It is therefore important to camouflage these more coarse-haired FU with additional rows of single-haired grafts anteriorly. Patients of African descent tend to have mesocephalic skull shapes of intermediate length and width that support hairlines that are flatter than Caucasian patients, but not as flat as those found in most East Asians. Unlike East Asian patients, however, a natural hairline appearance is more easily achieved in patients of African descent due to not only the hair curl and the finer caliber hair but also the minimal contrast between the color of the hair and skin, which creates an illusion of density and camouflages grafts.28 Therefore, multi-hair FU may be placed more anteriorly than in East Asian patients and just behind the hairline zone. The hairlines of Hispanics span the range between Caucasians and those of African descent.
Appropriate facial framing in female patients often entails a more rounded hairline design that incorporates observations from examination of 360 female volunteers: Creation of 1) a widow’s peak (observed in 81% of female hairlines), 2) an anterior midpoint placed a mean distance of 5.5 cm superior to the glabella, 3) lateral mounds with an apex 3.75 to 4 cm from the frontal midpoint (98% of females), 4) temporal mounds 3.5 to 3.75 cm lateral to the apex of lateral mounds, and 5) temporal recessions in a concave oval contour that contain fine hairs (87% of females).29,30 More often with females than with their male counterparts, native residual vellus hairs can serve as a guide in re-creating their hairline pattern.
Transplanting the midscalp region, especially in men, provides numerous aesthetic benefits and—due to its more conservative distribution—may be the most appropriate compromise in younger patients with a limited lifetime donor supply. Direct coverage from midscalp transplantation (Figure 52.11) not only improves density from a lateral and overhead view but also provides a thickened backdrop to a thinning frontal area as well as providing indirect coverage of a crown as transplanted midscalp hairs cascade posteriorly over it—particularly if a transplanted midline posterior “bump” is created.31
FIGURE 52.11. A. A 48-year-old man with diffuse hair thinning in the midscalp and vertex areas refractory to finasteride therapy. The 2,580 FU surgery transplanted at a density of 25 to 30 FU/cm2 covered the midscalp area and a small semi-circular “bump” protruding into the vertex. B. One year after a session, the hair is parted through the transplanted area for critical evaluation.
The decision to transplant a progressively thinning and expanding vertex carries an increased risk that an unnatural distribution of hair will result in the future in which an isolated island of transplanted hair may be surrounded by an alopecic scalp. Because the shingling effect of one hair lying over another is the least beneficial throughout the crown and specifically at the vertex, patients should also be advised that coverage may not have the same cosmetic impact in this region as elsewhere and, therefore, may require one or more additional sessions to the “whorl” of the vertex and possibly including peripheral areas of future hair loss. Due to this likelihood, the best candidates for vertex transplantation are patients past the age of 40 years with ample donor reserve and a minimal hair-to-scalp color contrast. For the majority of patients, the front and midscalp have first priority and most of the donor hairs should be reserved for those regions.
Transplantation procedures to reconstruct eyebrows were among the first hair transplantation techniques to be described and this area of the face continues to gain popularity (approximately two-thirds female and one-third male).32 The authors encourage patients to try treatment with topical bimatoprost ophthalmic solution 0.03% prior to considering hair transplantation, provided the hair loss is not cicatricial in nature. Most patients know the shape of the eyebrow they desire and can outline the design themselves. The eyebrow is divided into the head (medial one-fifth), the tail (lateral one-third), and the body (connecting the head and tail). The medial most aspect of the eyebrow head should have FU directed somewhat vertically while the direction gradually becomes more horizontal while proceeding laterally as the head transitions into the body (Figure 52.12). Angles should be as acute as possible, which may be facilitated by using counter-traction adjacent to the area where the recipient site is being created. The best donor harvest location (either via FUT or FUE) of the requisite 400 to 450 FU is an area of the scalp that most closely resembles the existing hair in the region. Often these are found in the mid-occipital region in which the necessarily fine hairs are also the least likely to be or become gray and have the best texture and curl. Although both eyebrow and eyelash transplantation can be used for cosmetic enhancement as well as reconstruction, patients must be well informed regarding the long-term need for routine trimming and curling of transplanted lashes. Scalp-to-beard and pubic hair transplantation also provide marked cosmetic improvement but that discussion is beyond the scope of this chapter.
In addition to designing the appropriate surgical pattern, a critical aspect of recipient site creation is minimizing trauma to both the scalp vasculature and the preexisting hair follicles within the area of transplantation. By minimizing underlying vascular trauma, the newly introduced follicles gain improved oxygenation, increased viability, and accelerated healing.31 Ultimately, what is most important is not how many hairs are transplanted but how many hairs grow (and of course in the natural angle and direction of preexisting hair). The most common causes of inadequate density after hair transplantation include 1) excessive injury to the blood supply; 2) insufficient number of grafts transplanted in the recipient area; 3) poor growth of transplanted follicles due to injury sustained out of the body (during dissection, storage, or implantation); and 4) inappropriate selection of donor hair from a region peripheral to the SDA.
A recipient site can vary in size, shape, depth, width, angle, and direction. Angle and direction are distinct entities. Angle refers to the degree of hair elevation as it exits the scalp. Direction refers to which way the hair points when leaving the scalp. Hair direction emanates from a whorl in the vertex, it is mainly posteriorly or anteriorly oriented within the caudal scalp, and it is inferiorly and often inferoposteriorly directed in the temporal and parietal regions. Although it has been demonstrated that more acute angles appear to increase perceived scalp coverage, it cannot be overemphasized that both the direction and the angle of the recipient site incisions should mimic the preexisting hair within the region of the scalp that is being treated.33 Traditionally, surgeons have oriented recipient sites parallel to the direction of hair growth (sagittally when within the caudal scalp). However, various surgeons advocate for orienting multi-hair FU incisions perpendicular to the direction of growth (coronally when within the caudal scalp). The surgeons who favor perpendicularly oriented sites believe that this results in a superior appearance of density, while those favoring parallel sites feel that the increased vascular damage outweighs any benefits.34
Multi-unit grafts (MUGs) may be utilized to create the illusion of increased recipient area density. These grafts incorporate 2 FUs that are chosen because their FUs are closer together than most FUs are. Their benefit of providing increased density is tempered by the increased challenge of ensuring their natural appearance. Therefore, they are only employed when hair characteristics and donor/recipient zone features favorable for MUG use in transplantation are present: 1) low hair-to-scalp color contrast; 2) fine diameter and wavy or curly hair (increases the shingling effect); 3) transplantation in the central forelock, midscalp, or anterior crown (zones where the hair can be acutely angled to produce a shingling effect); and 4) the presence of surrounding hair (either existing or transplanted) so as not to expose the MUGs over time.35
FIGURE 52.12. A. The eyebrow is divided into the head, body, and tail. It is slightly arched in females. The direction of hairs (white broken lines) in the head is more vertical, while hairs in body cross hatch (cephalic hairs angle slightly down and caudal hairs angle slightly up). (a) Peak of arch, finer hairs are chosen for the top border. (b) Slight narrowing on bottom aspect of body that helps creates the arch effect. (c) Medial border of head, which is rounded or square. (B) Before and after at 8 months, after 250 grafts to each eyebrow of a 38-year-old Caucasian female whose eyebrow loss was due to over-plucking as a teen: (B) before and (C) after. (Courtesy of J. Epstein, M.D. From Unger WP, Shapiro R, Unger R, Unger M, eds. Hair Transplantation 5E. London and New York: Informa Healthcare; 2011.)
When higher density is required and these four criteria are not met, high-density FUT or “dense packing” in targeted zones (defined as implantation of >30 FU/cm2) may be considered. When performed successfully, high-density FUT most closely resembles natural hair distribution, increases patient satisfaction, and minimizes the likelihood that patients will require a follow-up transplant to the same area.36 Disadvantages of this approach, in addition to increased vascular compromise, include the prolonged out-of-body period due to increased time for denser recipient site creation, production of more “skeletonized” grafts, and more challenging graft insertion associated with a greater potential for preexisting follicle transection, graft desiccation, and traumatic graft insertion, respectively.37 Using the “stick-and-place” method of implantation in which the physician makes an incision and immediately places a graft into the site can minimize some of these hazards.38 Benefits of this technique include minimal bleeding, decreased likelihood of empty sites or of those inadvertently filled by more than 1 FU (i.e., “piggy backing”), smaller incisions due to a shortened time for scalp recoil prior to graft insertion (resulting in less vascular trauma), the ability to adjust the incision size based on the fit of the grafts, and a simpler procedure for the assistant due to the ease of identifying the exact angle and direction of each recipient site. However, the greater demand for the physician’s time coupled with the limitations of only one pair being able to plant simultaneously discourage many practitioners from using this method.
Once the transplanted FUs have all been placed, many physicians place a postoperative bandage for one night over the patients’ scalp. Despite the additional public attention it may draw to the patient’s appearance, the postoperative bandage may promote wound healing by maintaining an appropriate moisture balance and prevent infection by providing a physical barrier to microbial invasion.39
Soaking the scalp after the bandage has been removed facilitates crust dissolution and helps prevent further crust formation. Since it may cause inadvertent graft dislodgement, patients are generally discouraged from shampooing their scalp for the initial 48-hours postoperatively, but are then encouraged to shampoo gently. For the same cautionary reasons, showering the recipient area is also reserved until after 5 to 7 days postoperatively. After moistening the scalp, ointments, or gels are applied twice daily along the donor incision and over the recipient area. The authors’ practice also encourages topical minoxidil application (3.5%) not only for its vasodilatory effects that may enhance wound healing but also because limited data suggest that minoxidil decreases postoperative effluvium.40 Continued minoxidil use is encouraged for 5 to 12 weeks postoperatively unless the patient develops scalp irritation, in which case it should be discontinued.
Postoperative pain is usually minimal and is limited to a feeling of tension along the donor wound. In addition to analgesic use (acetaminophen or narcotics), patients should ice a few times a day for 10- to 15-minute intervals along the nape of the neck (only inferior to the wound) to help minimize localized edema, which may cause increased tension in the donor area. Tissue edema in the forehead and temporal areas usually becomes most evident 3 to 5 days postoperatively. Rarely, this edema can descend into the periorbital tissue. To minimize the possibility of these sequelae, patients are also encouraged to ice their forehead and temples bilaterally and lie in a supine position as much as possible for the initial 72-hour postoperative period. The authors generally remove sutures between 8 and 10 days after surgery. However, sutures should be left in place for 10 to 14 days in patients with donor wound closing tension at either extreme (increased tension or excessive scalp laxity).
Rare donor area complications include temporary localized hyperesthesia, arteriovenous fistulas, and localized wound dehiscence, as well as aesthetic complications of visible scarring, keloid or hypertrophic scarring, or temporary donor hair effluvium.41,42 Within the recipient area, the extremely rare, but most serious complication of central recipient area necrosis results from vascular compromise and is more likely in smokers, diabetics, and patients who have undergone prior scalp surgeries.42 Ingrown hairs and folliculitis are a more common but less severe complication (2% to 10% of patients) that may be treated with either alcohol wipes or warm compresses three times per day or a course of a first-generation cephalosporin, such as Cephalexin, depending on the severity.
Although patients may vary considerably, substantial cosmetic improvement is present after 9 to 12 months, and the general timeline for hair growth after surgery is as follows: newly transplanted fine hairs begin to appear around the third or fourth postoperative month and the number and caliber of transplanted hairs continue to increase until full growth can be appreciated approximately 18 to 24 months after a session.
PERIOPERATIVE ADJUNCTIVE THERAPY
Finasteride 1 mg (a 5α reductase inhibitor) was approved for the treatment of AGA in 1997. Since the Food and Drug Administration (FDA) approval, 6.7 million patient years of exposure have resulted in a roughly 87% efficacy in slowing hair loss or increased hair counts, with a relative low adverse event profile ranging from 0.7% to 5.9% of patients.43,44 The degree of hair growth is most noticeable in the vertex and less dramatic in more anterior regions of the scalp. According to a 3,177 patient trial, the response rate improves during the initial 3 years of therapy before diminishing in approximately 14% of patients after a decade of therapy.45
Many surgeons encourage young patients to complete a trial of oral finasteride therapy prior to proceeding with surgery, especially in those who are destined to develop a severe pattern of MPB in the future and those in whom a thinning crown is of utmost concern. Alternatively, finasteride—as it is most effective in posterior scalp regions—may prove to be an ideal adjunctive therapy in a patient who opts for HRS in the frontal and midscalp areas.
This medication does not come without risk, however, and its image has recently been tarnished by accusations, including increasing incidences of high-grade prostate cancer (Gleason grades 7 to 10), depression, male breast cancer, and permanent sexual adverse effects.44 Although it has not been proven that these side effects are caused by finasteride, the FDA concluded that bias alone could not account for the trend of increased incidences of high-grade prostate cancer in patients taking finasteride 5 mg. Prescribing physicians should also inform their patients of finasteride’s influence on lowering prostate-specific antigen values. It has not been approved for use in women and should certainly not be taken by women who are pregnant. Topical minoxidil, with its beneficial effects of increasing the percentage of anagen hairs and enhancing local vascular perfusion, may be used alone or in combination with finasteride to slow the progression of AGA.
Autologous PRP administration is also an emerging adjunctive therapy requiring further investigation. In limited studies, it has been anecdotally reported that PRP injected directly into the scalp can increase overall hair counts and hair diameter while microscopic findings reveal thickened epithelium, proliferation of collagen fibers and fibroblasts, as well as greater numbers of blood vessels around hair follicles in areas that have been treated with PRP.46
TRANSPLANTING IN HAIR-BEARING AREAS
Young Male Patients
Young male patients in their mid-twenties or younger, who are frequently not yet completely alopecic but who request surgical intervention for their hair loss, represent the greatest challenge in terms of planning. This crucial time in a man’s life can be negatively impacted in a significant manner by the stigma of hair loss. The difficulty in planning is caused primarily by the uncertainty of the future pattern of MPB and is compounded by a young man’s expectation and desire often for a low, thick hairline. The surgeon should virtually never comply with such a request because the limited donor supply will not be sufficient to create appropriate density in a natural distribution behind such a hairline. A young man’s threshold for eligibility for HRS should remain high after a careful evaluation of their projected donor-to-recipient ratio. Medical adjuncts should then be presented in detail and strongly encouraged. The authors do believe, however, that—when performed prudently—young patients may benefit greatly from HRS and not be arbitrarily excluded by age alone (Figure 52.13).47
FIGURE 52.13. A. A 19-year-old man with severe hair loss in the frontal and midscalp areas before treatment. B. The area has been prepared with betadine solution to reveal the true extent of hair loss in the frontal and midscalp areas. C. A photo taken 12 months after one session to the frontal area and one to the midscalp area (a total of 4,244 FU) at a density of approximately 25 FU/cm2. The hair has been parted through the frontal area for critical evaluation. D. A photo taken the same time as (C) but with the hair combed as normally worn. E.A photo taken 4 years after the photos in (C) and (D) with the hair parted for critical evaluation. F. A photo taken 4 years after the photos shown in (D) with the hair combed as normally worn. Note that the hair after 4 years is not quite as dense as in (C) and (D). This was because the donor area hair density had decreased over that period of time, so the number of hairs per transplanted FU had, as expected, also decreased proportionately.31
In addition to the caveats addressed in the section focused on hairline design, an ability to consistently produce high hair survival rates at 25 to 30 FU/cm2 is important in order to be able to cover larger areas than can be treated if the graft density is high (including areas of future loss). This density and extent of coverage will help establish a relatively permanent pattern that will remain natural appearing when it exists on its own after the preexisting hair is gone. Avoiding transection of preexisting hairs is essential and, as noted earlier, the risk of temporary effluvium should be minimized by creating the smallest recipient site incisions that will accept grafts without over-handling and at as superficial a depth as possible. An extreme example of utilizing fewer grafts in order to create a natural long-term pattern that is ideal for younger individuals with family histories of type VII MPB is a “Prospective” Isolated Frontal Forelock.48
As with the younger male population, surgical technique for female patients emphasizes avoidance of existing follicle transection and temporary effluvium within the recipient area. However, because the donor area is often far more limited in women than in men, it is wise to employ strategic transplantation into the most cosmetically important areas of hair loss. That approach, combined with more styling options than men have, will ultimately provide the greatest illusion of overall scalp coverage. It is important to note that while some HRS find 20% or fewer of the women they see in consultation to be candidates for hair transplanting, a majority of experts polled on this subject felt 50% or more of those they saw were candidates.49
Surgical patterns previously described by the authors can be selected for the aforementioned areas of strategic coverage based on the patient’s particular presentation of FPHL (Figure 52.14).50 In patterns focused along a “part” line, the patient must specify where she would like to ultimately part her hair so that the improved density along that channel will yield the greatest cosmetic impact.
FIGURE 52.14. A. Four general categories of design utilized for female patients, which are then modified to cater to the exact needs of the woman. B. The general designs address the various patterns of female pattern hair loss (FPHL) and (C) are ultimately applied to the individual female patient.
ADJUNCT TREATMENT FOR FACELIFTING
Face lifts may leave permanent signs, including discoloration of either the temporal or postauricular hairline. Even well-placed pretrichial incisions may widen or become hypochromic, revealing that a patient has undergone a cosmetic operation. Fortunately, HRS, when performed by an experienced surgical team, provides an excellent adjunct to conceal undesirable discoloration, scarring, or displaced hairlines secondary to these procedures.51
An exposed temporal or preauricular scar is effectively concealed by re-creating a “sideburn” with fine caliber hair grafts. Regions of cicatricial alopecia in the postauricular region can also be camouflaged by transplanting both within and around the scar (Figure 52.15). With all areas of cicatricial alopecia, whether the skin surface has been previously traumatized by a burn, reconstructed with a skin graft or flap, or rendered alopecic from mechanical trauma (such as trichotillomania, traction alopecia, and a dermatologic pathology), preserving the already-compromised underlying vascular perfusion is paramount. This may be aided by both avoidance of epinephrine use when anesthetizing the area and transplanting at a graft density that is not high enough to overwhelm the limited vascular supply. Repeatedly assessing variations in perfusion while making incisions can help determine if it is best to use either a 15 to 20 FU/cm2 density in an area of low perfusion or up to a 30 FU/cm2 pattern where blood supply is sufficient.52 As dermal recoil and laxity are often limited in recipient areas of cicatricial alopecia, it is critical to optimize recipient site size to allow a “snug” fit of the grafts to ensure minimal graft handling by prevention of repeated “popping” or slipping out of grafts above the surrounding epidermis.
RECONSTRUCTIVE AND CORRECTIVE HAIR TRANSPLANTATION
The art of softening and camouflaging the “pluggy” appearance of a previous transplant involves not only the implantation of individual FU but also the removal of specific offending “plugs” (Figure 52.16). Partial excision of a plug using a 1.5- to 2-mm punch biopsy instrument removes a substantial amount of the plug hairs while leaving behind a crescent of a few remaining hairs that will appear softer and more natural, especially if surrounded by newly transplanted FU. Determining the proper angle and direction of extraction is facilitated by trimming the offending plug hair to 3 mm in length. This also gives a sense of the overall appearance once it is removed. Passing the punch deep enough to include 1 to 2 mm of subpapillary adipose tissue not only minimizes the likelihood of regrowth of the offending hair but also enhances viability of the excised portion of the plug as it is trimmed and recycled for subsequent transplantation into a more appropriate portion of the scalp. When individual FUs are transplanted around a plug reduction site smaller than 2 mm, the biopsied sites should not be sutured closed as this would reduce local blood flow and increase localized scalp tension—both variables detrimental to neighboring transplanted graft survival.53
FUTURE OF HAIR TRANSPLANTATION SURGERY
The advent of robotics in hair transplantation currently allows for automated harvesting of hair follicles using the FUE method. Ultimately, the day will come when robots will automate the entire hair restoration procedure, performing both retrieval and implantation. Even with robotic assistance, however, the drawbacks of FUE remain (potential decreased graft viability secondary to denuded grafts, and noticeable punctate scarring in the donor region if grafts are taken too closely together or with too large a punch) and the artistry of surgical pattern creation may be limited.
FIGURE 52.15. A. Browline and B. Postauricular regions of cicatricial alopecia of two different patients following a facelift procedure. These areas made it difficult for the patient to wear her hair in any up-swept hairstyle which she favored in the summers. C. Preauricular area also showing scars and regions of complete alopecia following the facelift. The patient wanted her hairline and “sideburn” re-created. D. Browline and E. postauricular area following one hair transplant surgery. The area of cicatricial alopecia has good camouflage and the only remaining scar, which is slightly visible is the hypo-pigmented incision scar. It is important to remind patients that although the hair will grow through the scar, any skin discoloration may still be detectable upon close inspection. F. Preauricular area postoperatively. A natural hairline has been re-created and the patient now can wear her hair tucked behind her ear as was her custom prior to the facelift procedure.
FIGURE 52.16. A. A patient before repair of transplanting done in another office. The areas to be treated are outlined in black grease pencil and the results after 1,973 FU can be viewed (B) 10 months later.
Cell therapy in HRS remains on the horizon. Stem cell–rich regions of the hair follicle are believed to be the mesenchymal cells located at both the bulb region (dermal papilla) and the bulge region. The concept of isolating hair follicle stem cells and propagating them in vitro to generate new hair follicles was proposed over two decades ago. It was believed that autologous implantation of these replicated hair follicles into the balding scalp would generate new hair follicles. The promise of overcoming the shortcomings of current transplantation methods (a limited donor supply and scarring from donor excisions) generated tremendous interest in cell therapy. Hair follicles have successfully been induced in rats and athymic mice using dermal papilla grown in culture media, and to a limited extent in their human donors.54,55 However, thus far, consistent growth of significant amounts of hair from such has not been accomplished in humans. Ultimately, tissue engineering of hair follicles must also comply with the rigorous standards set forth by the U.S. Food and Drug Administration.
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