Follicular Transportation (part 2)
THE DONOR BANK
There are two processes that occur simultaneously in the balding individual. One is androgenetic alopecia, i.e. the patterned hair loss programmed to affect only certain hair follicles in susceptible individuals, and hair loss due to aging itself, which to some degree affects all hair in everyone. The donor region in the back of the scalp where hair is traditionally harvested from has been optimistically called the “permanent zone”; however, this zone is far from permanent. It may be spared from the process of genetic balding, but it is surely affected by the aging process itself. It seems that on the average the donor site thins at least 30% over one?s lifetime due to simple aging. In some men with extensive balding, the permanent hair seems to be affected by the genetic process as well, and when these two processes occur together, the decrease in donor density can be marked with counts occasionally falling below one hair/mm2. This process is probably analogous to the extensive diffuse thinning seen occasionally in women. The continued loss of hair in the permanent zone over time must, of course, be accounted for in the planning of the hair transplant and in giving a realistic prediction to the patient of the long-term stability of the transplanted hair.
Two major factors determine the amount of hair that can be safely removed from the donor area. The first is donor density, and the second is scalp laxity. The importance of accurately assessing donor density cannot be over emphasized. At the initial consultation, density determinations are made from a representative area in the permanent zone where the donor strip might be harvested. If there is significant clinical variability in the donor density or scarring due to prior surgery, then multiple measurements are taken. These numbers are used in the initial planning of the procedure. At the time of surgery, the density is measured again, calculations are taken to determine the length and width of the donor strip, and the area is then prepped and shaved. The shaved donor site is then inspected for irregularities of density due to natural variability and those resulting from scarring due to past procedures. Multiple determinations are made again and averaged to accurately assess the density. Our experience has shown that the gross visual impression of density is often at variance from the true density by a factor of up to 35% and is far too imprecise to be useful in surgical planning.
Scalp laxity is a more subjective measurement, but with experience can be estimated with a reasonably high degree of accuracy. Judging scalp mobility by simply moving the scalp up and down with the hand or tenting of the skin between the fingers are the two obvious means of assessing laxity. Also useful is noting the thickness of the scalp (an abundance of subcutaneous fat makes for a mobile scalp) and observing the configuration (contour) of the cranial bones. Prominent mastoid processes and occipital notches decrease the ability to easily close a horizontal incision. We use a Rassman knife that when fully loaded with 8 blades produces a strip 21mm in width. By removing blades, one can harvest strips of 18mm, 15mm, 12mm, 9mm and so on. Generally, the widest strip that can be harvested without producing undue tension during closure should be used. If a strip is too narrow, then its length must be increased to yield the same amount of hair and a longer incision produces more donor site scarring and distortion. If a strip is too wide, then tension on the wound edge may result in dehiscence, infection, excessive post-operative discomfort, prolonged wound healing or a hypertrophic or spread scar. In general, the greatest degree of tension occurs over the mastoid processes, and great care should be taken when estimating scalp mobility in this location. If it is anticipated that this area will be a limiting factor in the harvest, then it is best to use a more conservative width and excise a longer strip. In patients having a very prominent occipital protuberance, the greatest tension may be at the midline. In this situation one may either remove a blade to narrow the width as one extends medially or to harvest an additional strip on one or both sides freehand. On occasion, when a patient with a prominent ridge has had multiple previous surgeries, the strip is harvested in two separate pieces neither extending to the midline.
The plane of dissection should be just below the hair follicles in the superficial fat to avoid damaging the larger nerves and blood vessels which lie deep in the subcutaneous layer, just above the galea apounurotica. If possible, the galea should not be violated as this fibrous band serves as the structural support of the wound closure and prevents its spread. Suturing a transected galea will never approach the strength of the membrane left intact. In addition, dissection in the subcutaneous layer avoids the necessity of a layered closure and its associated foreign body reaction. In very large sessions where up to 50 square centimeters of scalp may be removed and the incision length can be 30 cm, the importance of superficial dissection and leaving the galea intact cannot be over emphasized. In addition, we never undermine. In the rare instance where the wound edges cannot be approximated, it is better left to heal by secondary intention rather than to risk damaging hair follicles, blood vessels or nerves. Any cosmetically unacceptable scar can easily be removed in the future after the scalp tension has decreased. We also do not electrodessicate. Bleeding generally occurs at the wound edges and is controlled with a running cutaneous suture. On rare occasion, a larger vessel is ligated using 4-0 Vicryl, if it would not be incorporated easily in the closure.
We use a single running suture of 2-0 polypropylene. The sutures are generally left in place for two weeks. However, if there is significant tension during the closure then these sutures may be left in place for three or more weeks as polypropylene produces little tissue reactivity. The entire length of the suture line is kept covered continually with a topical antibiotic in an ointment base (Bacitracin). At the time of suture removal, the sutures should protrude slightly above the scalp surface which indicates that edema and inflammation have significantly subsided. This is in sharp contrast to sutures left in glaborous skin, which become progressively more embedded the longer they are left in place. In patients without penicillin sensitivity, we pre-medicate with Dicloxacillin 1gm PO, 1 hour prior to surgery, and then a second dose of 500mg PO 6 hours later if there was excessive bleeding, or wound tension.4
In determining the position of the donor incision, it is best to assume that the patient may become a Norwood Class 7; therefore, the hair transplant surgeon should place the upper blade of the rake at least 1cm below the lowest point of possible hair loss. This will allow for coverage of the scar in the worst case scenario. As the incision extends laterally, it should be at least 1 cm superior to the top of the ear. It is important to stay very superficial in this area, especially as one extends the incision towards the temples, as the parietal branch of the superficial temporal artery and vein as well as branches of the auriculotemporal nerve lie very close to the undersurface of the dermis in this location.5 The excision should not extend anteriorly to a position closer than 3 cm from the hairline. Some patients may have extensive bitemporal recession, and this should be anticipated by carefully assessing the extent of the patient?s current recession, the degree of miniaturization at the free edge, and the family history.
Traditional surgical techniques have often left a “step-ladder” pattern of scarring in the donor area. When there is a preexisting horizontal linear scar (or scars), the scar may be totally avoided, totally incorporated into the new strip, or incorporated into one edge of the new incision. If the scar is in a position where it is already placed too high and may possibly be exposed with further balding, it is best avoided. If the scar had been placed too low, it is also best avoided to reduce the chance of hypertrophic scarring. Also if the donor area is relatively tight from prior surgery and if the scar is not visible, it may be left in place, as removing it will only increase wound tension. Avoiding the scar will maximize the yield of hair for that particular procedure. One may totally incorporate the scar if it is clinically visible and if there is enough laxity to remove it and still obtain the desired amount of hair. It is critically important to ascertain why the patient scarred in the first place. If the scar was a result of poor surgical technique and the problem can be identified and corrected, then excising it may be appropriate. If the scar (either stretched or hypertrophic) was due to the intrinsic healing properties of the individual (as seen in Ehlers-Danlos syndrome), then the scar is best avoided, because removing it will further increase wound tension, and the problem will most likely reoccur. It is important to assess the impact of the scarring on the average donor density as small amounts of scarring can significantly decrease hair yield due to distortion of follicles in the surrounding area. In the majority of instances, we opt for the third choice i.e., using the previous scar as the upper or lower boarder of the new excision. We will remove all but approximately 1.5 mm of the width of the scar to allow the suturing to be limited to the scarred area and not to extend into viable hair bearing scalp. In this way the amount of distortion and possible damage to existing hair is limited to only one free edge.
Strip Length
Accurately estimating the size of the donor strip and the amount of hair that it will contain is more difficult in follicular transplantation but also more important because of the large tissue requirements. We find that precise measurements are essential in this regard. As in the assessment of density, a clinical “feeling” about the size of the strip needed is far too imprecise to be relied upon to guide the surgery. To calculate the length of the donor strip we use the following equation (A), or its derivative (B):
(A) Strip Leangth(cm) = # of Hairs Transplanted/(Donon Density/mm2)(1-DS)(1-CF)(# of Strips X 0.3cm) X 100
Density and Donor Supply
An accurate assessment of the total moveable donor reservoir of hair is critical for long-term planing. In our experience, the average donor density for all patients (both bald and non -bald) seeking a consultation for hair restoration surgery have an average donor density of 2 hairs/mm2. In general, for individuals with straight hair of average diameter, the donor density must be at least 1 hair/mm2 in order to adequately cover the donor area and not have it appear too thin. A density of 1 hair/mm2 is also the minimal density needed to hide an average donor scar. If a patient has wavy or thick hair the minimum density may be slightly less and in patients with very fine, straight hair the minimum density will be more.
The limitations placed upon the amount of harvestable donor hair due to these minimal density requirements needed to cover the donor area, create a relationship between donor density and donor reservoir that is not one to one. A unit change in donor density away from the norm will produce a two-fold change in the availability of transplantable hair. For example, compared to the average person (with a donor density of 2.0), a balding individual with a donor density of 2.7 (which is a 35% increase) will have 70% more hair available to transplant. Conversely, a person with a donor density of 1.3 will have 70% less transplantable hair, and may not be a candidate for surgery regardless of his Norwood classification. If he were to bald extensively, almost any type of surgical hair restoration would leave him desperately short of hair and short on coverage in the donor area. Unless the hair restoration surgeon is aware of this relationship, miscalculations will be made when relying on absolute donor density in assessing total donor supply.
The importance of using the densitometer in assessing donor supply cannot be overemphasized. With multiple procedures, each harvest decreases the remaining donor density, and this measurement, together with the decrease in scalp laxity, will give a good indication of what can be achieved in the subsequent surgery. Women with non-patterned diffuse alopecia often have donor densities in the range of 1.0 to 1.5, and for similar reasons are also not good candidates for transplantation.
PREPARATION, HANDLING, AND PROJECTION of THE FOLLICULAR IMPLANTS
The basic concept in dissection is to identify the patient?s natural hair groupings and to isolate individual follicular units. A delicate balance must be reached between the goal of having the implant purely follicular and leaving enough peri-adventitial stroma to ensure that the implant is not damaged and hair is not wasted. This balance is achieved through the extensive experience of a highly motivated staff that are trained specifically for this task. Because the implants are so small, they are more sensitive to desiccation and temperature change. Therefore, handling and quality control at every level of the procedure are crucial to obtaining good results.
The initial harvest scores the strip just below the level of the hair follicles into 0.3 cm wide longitudinal sections with each attached to the other by the loose connective tissue of the subcutaneous layer. The sections are cut into pieces 1 cm in length. Each piece is then further subdivided, and the follicular units are identified, under magnification, and dissected free of surrounding skin. We prefer a #10 Personna blade and cut on tongue depressors that have been soaked in sterile water (not saline) until they are ready to be used. Immediately before use the excess water is removed with a piece of gauze. The purpose of soaking is to help maintain the moisture of the implants and to prevent the tongue depressors from absorbing water from the saline soaked implants, thereby increasing the relative concentration of the saline.
Dissection of the follicular units is the most labor intensive and critical part of the follicular implantation process. We use up to 12 highly trained cutters to produce the implants for a single large case. Proper planning of the recipient area is absolutely dependent upon accurate information regarding the yield of the donor harvest. The dilemma in planning is that waiting until all the units are dissected before implanting extends the length of the surgery beyond medical feasibility and starting before the surgeon has information about the total number of 1, 2 and 3 hair units, limits the ability to make precise decisions regarding size, density and distribution of the recipient sites. Although it would seem that information gleaned from pre-operative densitometry measurements together with the patient?s hair characteristics and the calculations described above would be adequate for the creation of the recipient sites, in actuality, once the dissection begins, new crucial information is obtained. For example, patients with gray-white hair can have either dark or light roots. In the latter case, due to decreased visibility, the cutters must leave more stroma around the units, increasing the implant size. As a result, a two-hair implant might require the same size site as a three-hair unit. On the other hand, in patients with fine hair, two hair units may be placed in a site made to accommodate single hairs. In patients with kinky hair, the hair shaft is often so curved below the level of the skin that close dissection of the units is impossible… but sometimes it is not, and the kinky hair behaves during dissection as if it were straight. In all cases, the smallest possible site is used for the respective implant in order to minimize injury to the recipient site and to allow for the very close placement of the follicular units.
In order to take into account these variables, the staff is instructed to take random pieces from the cut strip, and representative units are matched with sample sites. Placing of sites is then limited to the frontal hairline until the first projection of the implants is made (Table 2). Accurate projections of the total number of units that will be obtained from the donor harvest are critical for the correct placement of the sites with respect to size, density and distribution, allowing the creation of sites to proceed while the cutting is still in progress.
Table 2. Projection Worksheet. A sample of the projection worksheet used by our staff. In the example that follows, a strip removed with an eight bladed scalpel measuring 2.1cm x 24.2cm was subdivided into 142 pieces prior to dissection.
PROJECTION WORKSHEET
Patient?s Name ___________________ Date _________ Suite #______
Case Organizer _________________
Count #: _____ CUT: ____ corners _____ pieces TOTAL: _____ corners ______ pieces
Cutters: 1?s 2?s 3?s 4?s TFU?s
1 ____ ____ ____ ____
2 ____ ____ ____ ____
3 ____ ____ ____ ____
4 ____ ____ ____ ____
5 ____ ____ ____ ____
6 ____ ____ ____ ____
7 ____ ____ ____ ____
8 ____ ____ ____ ____
9 ____ ____ ____ ____
10 ____ ____ ____ ____
11 ____ ____ ____ ____
12 ____ ____ ____ ____
sum of cut pieces: ____ ____ ____ ____ = ______
number of cut pieces: ____
average units per piece: ____ ____ ____ ____ = ______
average x total pieces ____ ____ ____ ____ = ______
corners (2) ____ ____ ____ ____ = ______
Total Projected ____ ____ ____ ____ = ______
Instructions
To project the number of follicular units (FU?s):
1. Cut both corners and then begin to cut pieces.
2. Take an estimate after both corners and approximately 20% of the pieces have been cut and subsequent counts as
required by the size of the case.
3. Count 1, 2, 3, 4 and Total FU?s of corners and keep these numbers separate.
4. Count 1, 2, 3, 4 and Total FU?s, of the cut pieces, divide by the number of pieces cut to find the average number
of units per piece. Then multiply the average of each piece by the total number of pieces.
3. Add 1, 2, 3, 4 and Total FU?s of corners + projected 1, 2, 3, 4 and total FU?s of pieces = PROJECTION.
Both the cut pieces and individual implants are held in 0.9% Saline chilled to 59of. They are never out of chilled solution longer than 3-5 minutes. The placers rest a small amount of follicular units on back of the opposite hand used to hold the forceps. The placers wear powder-free gloves and place gauze under the glove beneath the area where the moistened implants will lie to prevent heat transfer from the hand into the implants. Implants are inserted with curved jewelers forceps. At the beginning of the placing, each assistant will determine his placing speed, which depends upon their skill and the patient?s specific hair and scalp characteristics. Once they have determined their speed for the specific case, it is easy for them to determine the amount of grafts that can be safely handled at any one time.
Hydrogen peroxide is very effective in removing residual blood from the scalp and acting as a mild hemostatic agent through a variety of possible mechanisms,7 and although it seems to produce little significant toxicity in normal usage, we exercise great caution during follicular transplantation and avoid its direct use on viable tissue. Fortunately, hydrogen peroxide is rapidly broken down to oxygen and water. In order to minimize its contact with the implants or with open wounds, we never spray or apply peroxide directly to the scalp. We use a 3% hydrogen peroxide solution diluted to 1 part hydrogen peroxide to 4 parts water, making an effective concentration of hydrogen peroxide of 0.6%. Any bleeding in the recipient area is stopped by applying direct pressure with dry gauze, not with peroxide. After the bleeding has subsided, 3×3 gauze is sprayed with the diluted peroxide and then applied to the skin to remove residual blood.
DESIGN of THE RECIPIENT AREA
In Follicular Implantation, we use five major elements to guide the creation of the recipient sites:
1) produce a natural pattern 2) frame the face and spare the crown 3) eliminate contrast 4) have the hair emerge at natural angles 5) and have a natural distribution of follicular units. Although an in-depth discussion on design is beyond the scope of this article, we would like to briefly explain the importance of these elements.
Natural Pattern
To a large extent, the correct template for hairline placement, hair distribution, and density has already been supplied by nature. The closer one follows the pattern set by nature, the more natural the hair restoration will appear. A hair transplant no matter how dense or how perfectly executed will look artificial unless it produces a look that others can recognize as one they had seen before. Just as the follicular implant attempts to mimic the way hair grows in nature on a microscopic level, the overall design of the follicular implantation should strive to mimic nature on a gross level.
The power of “The Isolated Frontal Forelock” recently described by Marritt and Dzubow8 lies in the fact that they identified a pattern seen in nature that was reproducible within the limits of the patient?s donor supply. However, the use of larger grafts for the dense posterior component limits the amount of available donor hair, and creates a natural look only when disguised by the anterior component. The main limitation of flaps and scalp reductions (even in the best of circumstances where there are no complications) are that although they achieve high density, there is no natural counterpart to the distribution they produce. Flaps bring the patient?s donor density to the frontal hairline, with a sharp demarcation anteriorly and posteriorly, a pattern never seen in nature. This area of high density must then be supported by a similar density around it to look natural and, of course, if the patient had enough hair to accomplish this, he wouldn?t have needed hair restoration in the first place. The scalp reduction, although appealing on a superficial level (“remove the bald area so there will be less area to transplant”), violates the same rules of nature as does the flap. A scar is placed in an area that should have light coverage (if any), the direction of hair is changed, the pattern of future balding of that crown will be altered, and donor density is decreased. In effect, scalp reductions are a “crown transplant” and thereby reduce the hair available for the cosmetically more important front.
We feel that the optimal way to plan a hair transplant procedure would be to first assess the patient?s present pattern of loss and to anticipate his possible future pattern (considering his present age and familial hair loss patterns) using the worst case scenario as a reference point. Next, determine a person?s total donor reservoir of hair (taking into account absolute donor density, degree of miniaturization, hair groupings and scalp mobility). Then, carefully analyze his specific hair characteristics which affect the appearance of fullness and naturalness (such as wave, hair shaft diameter and skin/hair color contrast). With this information in hand , one can realistically plan how far back in time one can go along his hair loss continuum, given the patient?s particular resources.
For example, a 55 year old Norwood Class 4 with a donor density of 2.3 and 20% miniaturization in the donor area and wavy hair, may be safely restored to a Class 3 using 1700 follicular units (Table 3). On the other hand, a 23 year old Class 5 patient with a donor density of 1.9 and 35% miniaturization in the donor site, with fine, straight hair should be restored to a Class 3 Vertex, rather than a regular Class 3. using 1500 follicular units. In this situation, we would use 1500 follicular units and leave the crown untreated. If he were to bald extensively, he might end up years later with an isolated tuft of hair in the crown, without enough donor reserves to complete the hair transplant.
Frame The Face and Spare The Crown
The patient judges the success of his hair restoration by its ability to enhance his appearance, which is in large part based upon the ability of keeping his facial features in proportion. In this regard, the second important element in proper planning is to make every effort to “frame the face”. Transplants which add density to a hairline placed too high (in the hope of conserving donor hair) only accentuate the patient?s baldness by elongating a bald forehead. It frames the forehead rather than the face. We generally place the frontal hairline one fingerbreadth (2cm) above the uppermost brow wrinkle (mature hairline). It is important to differentiate this from the patient?s original hairline which sits directly above the brow wrinkles, lacks bitemporal recession, and should not be used as a landmark for planning the hair transplant. When the donor supply is limited, it is much better to compromise towards the crown than to compromise the critically important position of the frontal hairline.
The decision to transplant the crown is an important one, because compared to other areas of balding, it is the least visible but occupies the greatest area. The progressively balding crown can produce huge demands upon the donor supply, and because this area is also the least stable, hair must always be reserved for this eventuality. Furthermore, the crown expands centrifugally, rather than in the predominantly anterior-posterior direction of the front and top, with the center of the crown always having the least amount of hair and being surrounded by areas of increasing densities. Because of this, any hair placed in the center of a balding crown can result in an island of hair surrounded by a moat of bald skin. To correct this, hair of increasing density must be added around it to be aesthetically balanced, consuming vast amounts of hair that could be better saved for the front. Because of these issues, we generally reserve treatment of the crown for older patients with above-average donor density and stable hair loss of Class 3 Vertex, Class 4, and Class 5, or patients of Norwood Class 6 with high donor density and good scalp mobility (Table 3). If extensive balding is a possibility, it is always best to treat the crown as an extension of the top, rather than as an isolated region to ensure that you will not be short of hair if the intervening region were to bald.
REFERENCES
1. Headington JT: Transverse Microscopic Anatomy of the Human Scalp. Arch Dermatol 1984; 120:450.
2. Rassman WR, Pomerantz MA: The Art and Science of Minigrafting. International Journal of Aesthetic and Restorative Surgery 1993; 1:28-29.
3. Stough, DB: International Society of Hair Restoration Surgery, Third Annual Meeting 1995; Verbal Communication.
4. Haas AF, Grekin RC: Antibiotic Prophylaxis in Dermatologic Surgery. JAAD 1995; 32:155-164.
5. Salasche SJ, Bernstein G, Senkarik M. Surgical Anatomy of the Skin. Norwalk, Connecticut: Appleton and Lange, 1988 pp 176-177.
6. Rassman WR, Carson S: Micrografting in Extensive Quantities, The Ideal Hair Restoration Procedure. Dermatologic Surgery 1995; 21:306-311
7. Larson PO: Topical Hemostatic Agents for Dermatologic Surgery. J Dermatolgic Surg. Oncol. 14:6 1988.
8. Marritt E, Dzubow L: The Isolated Frontal Forelock. Dermatologic Surgery 1995;21523-538.
9. Transplant Videografting System of the Professional Hair Institute; displayed at the International Society of Hair Restoration Surgery, Third Annual Meeting 1995.
About the Author
Dr. Bernstein is Clinical Professor of Dermatology at the College of Physicians and Surgeons of Columbia University in New York. He is recognized world wide for pioneering Follicular Unit Hair Transplantation. Dr. Bernstein’s hair restoration center in Manhattan is devoted to the treatment of hair loss using his state-of-the-art hair transplant techniques.
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