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PATIENT GUIDE TO SURGICAL & MEDICAL HAIR
RESTORATION
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Following the Example of Nature |
| Only in the early 1980’s was it been
recognized that hair grows not singly, but in specific anatomic units that are
called follicular units (FU’s) (see figure 1). These consist of one, two, three,
four, or rarely five terminal (mature) hairs, one or two vellus (fine) hairs, a
discrete nerve and blood vessel supply, a connective tissue sheath, sebaceous
glands, and a tiny muscle known as the erector pili. These FU’s are the natural
groupings of the hair, the way it normally grows. It seems intuitively obvious
that a natural transplant would follow the form of nature and use strictly FU’s.
This has, unfortunately, not been the case. |
Figure
1
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| It would be expected that using this
method would allow us to create the most undetectable result, and also allow us
ease in following the natural angles of emergence from the scalp. These angles
at which the hairs exit the skin are quite important, as they vary widely
depending upon the area of the scalp we are observing. Also, improved survival
may result from this technique. Consider the old, large plug techniques. The
recipient site was actually created using the same type punch that was used to
harvest the graft. In other words, tissue was removed. This not only created the
potential for scarring and "cobblestoning", it could compromise the blood flow
beneath the scalp as well. In addition, the size of the grafts themselves could
limit the flow of blood and oxygen to the hairs in the center of the graft,
leading to "donutting". On the other hand, using FU’s requires only a tiny
recipient site in the scalp; we often use only a hypodermic needle to make these
miniscule slits! Thus, healing is much quicker, there is less post-operative
evidence of the procedure (even the next day), and there is minimal excess
tissue subject to scarring and other complications. |
Minimizing Donor Hair Wastage: Mathematical Planning |
Research has shown us that for Asians and
Caucasians, the density of follicular units, regardless of the number of hairs
they contain, is about one per square millimeter (1FU/mm2). For African type
hair it is less, approximately 0.6FU/mm2, although this is more than made up for
by the preponderance of three hair FU’s, versus two hair FU’s in Asians and
Caucasians.
We can directly measure not only the FU density, but the hair
density as well, by using a tool called a densitometer. With small areas of hair
clipped short, a fixed area is observed under bright light and magnification.
Then, we can calculate the appropriate numbers, for example: we can look at the
density of FU’s and hair in the center of the back of the head, over the ear,
and halfway in between. If the numbers average 1FU/mm2, and 2 hairs/FU, and the
patient will be receiving 1500 grafts, then we can calculate that we will need
to harvest about 15 square centimeters (cm2) from the back and side of the head
to give us our required grafts. We can also assume that, given a 20% occurrence
of single hair grafts in those with average density, our 20cm2 donor strip will
provide us with about 300 single hair grafts, which should be enough for our
hairline transition zone.
Moreover, we can use calculations to plan for the
future. The average, non-balding person has about 100,000 hairs on the scalp.
This would translate to 50,000 follicular units (FU’s). The "permanent zone"
comprises about 25% of the total scalp; therefore, there would be one-fourth, or
25% of these total 50,000 FU’s in the permanent zone, which would equal 12,500
FU’s. We know that about half of the hairs in an area must be lost before there
is any appearance of balding, so we could safely harvest up to half of the
permanent zone FU’s, or 6,250 FU’s. This gives us an idea of the viable,
reasonable donor reserves that a given patient has for current and future
transplantation.
It is important to realize that the amount of coverage and
density that a given person achieves with FU transplantation will vary not only
according to their donor density and scalp laxity, but also according to their
hair characteristics. This is another point where art meets science in the field
of hair transplant surgery. |
Hair Characteristics in Follicular Unit Transplantation |
The characteristics that are most cosmetically
important are: hair color (especially relative to the underlying skin color),
hair curl (or lack thereof), and hair caliber, or cross-sectional area (in other
words, is the hair shaft itself fine, or coarse). The artful hair restoration
surgeon will take all these factors into consideration when planning a
procedure, in order to give the greatest aesthetic benefit to the patient, with
the minimal use of the limited donor hair.
Hair caliber, or cross-sectional
area is actually more significant than density in its ability to "cover" bald
scalp. Remember that the appearance of baldness is actually due to light
penetrating past sparse or absent hair, and then being reflected off the shiny
scalp. The more hair that is in place to block the light, the less the
appearance of baldness will be. It can be mathematically shown that doubling the
caliber of hair would do more to block light than doubling the density. However,
there are other important factors.
One of these is the degree of curl.
Generally speaking, the more curl or wave the hair possesses, the more coverage
it will grant the scalp. An excellent example of this phenomenon is found in
African-type hair. This hair tends to be tightly wound or kinky, which may be an
evolutionary adaptation to protect the scalp in hot climates. Although African
follicular unit density tends to be lower than that of Caucasians or Asians,
(0.6 FU/mm2 vs. 1 FU/mm2), the curl characteristics lend this type of hair
wonderful coverage properties, as it tends to stand thick and mat-like above the
scalp, thus blocking much light. Also, an added advantage is that African hair
tends to occur predominantly as three hair units, rather than the two hair units
characteristic of Caucasians/Asians with average density.
Hair color,
especially as it relates to underlying skin color, is also of great importance.
The less contrast there is between hair and scalp, the better the potential for
coverage. A blond person with light skin, like someone of Scandinavian origin,
appears bald only after significant hair loss has occurred. This is because the
observing eye sees a high contrast as standing out in stark relief, and areas of
low contrast blend together. So even though many Asians have good density and
excellent hair caliber (coarseness), they may be challenging hair transplants.
Imagine dark, straight, coarse Asian hair contrasted against relatively light
scalp skin; the eye notes the contrast, and sees the light that has been
transmitted. The eye follows the straight hair shaft right down to the scalp,
and it appears balder than in someone with more favorable hair characteristics.
We can see, therefore, that a combination of many factors play a part in
determining who will be a poor, good or excellent candidate for hair transplant
surgery with follicular units. High density is great, but unfavorable hair
characteristics may attenuate some of the benefits of this density. On the other
hand, someone with curly, coarse, salt-and-pepper hair (very good
characteristics), but with poor donor density and a tight scalp, may also not be
the ideal candidate. This is where the artistic, knowledgeable hair restoration
surgeon really shines: knowing how to work with the positive resources the
patient does have, to insure the best possible outcome for the present and the
future. |
The Recipient Incisions |
It is without question that, of all
current graft types, follicular units can be placed into the smallest incisions;
consequently, they can be placed in closer proximity in the scalp. Although it
is not necessary to come close to the patient’s original density when
transplanting, there is a certain minimum required to obtain coverage; also, the
hairline especially needs closely, although somewhat randomly, placed single
hair grafts to give the illusion of graded density.
Small incisions,
moreover, simply heal more quickly than larger ones, and the grafts placed are
less likely to suffer from blood-flow and oxygen deprivation. Any incision can
damage the circulation of the scalp, cause scarring, and effect wound healing,
hair growth, and even the potential for subsequent transplantation. In addition,
small recipient sites, made with needles or micro blades, conserve the normal
matrix structure of the scalp’s connective tissue. This allows the FU’s to fit
snugly within the created sites, avoiding dislodgement, and promoting quicker
healing and immediate nourishment of the grafts from local blood supply. We
discussed earlier the slow and repetitive process of using large, standard
grafts; only so many could be placed at one time. With follicular unit
transplantation, however, sessions placing as many as 2000 to 3000 grafts at
once, and more, have become routine for us. For many patients, this may be the
only procedure they ever need! |
Large Sessions: The Rationale |
Let’s talk for a moment about large
sessions. As it has become apparent that excellent growth can be realized with
large FU sessions, other benefits have become manifest. For one thing, it
advances the hair restoration process expediently. Most patients have no desire
to get ensnared in a lengthy, repetitive series of treatments that they might
even have to terminate prior to completion. A large session of FU’s, in some
patients, can create a natural, undetectable result; this transplant can stand
on its own, and continue to look natural even in the face of further hair loss,
and without the necessary need for further work. In short, the process is just
plain expedient and efficient.
Also, every time a procedure is done, the
donor area is "violated". One large, single strip harvested from the donor area
will, by definition, create significantly less scarring, hair loss, and
distortion of remaining hairs than will multiple, small strips, or, even worse,
punch grafts. Minimizing the number of harvests, careful suturing and closure of
the donor site, and close attention to harvesting technique can be invaluable in
preserving precious donor resources; this is important not only in the event
that further transplantation is desired, but also in preserving the cosmetic
integrity of the donor area. We will discuss the often forgotten and
underappreciated donor area at length in a subsequent section.
The
possibility of telogen effluvium must also be considered with any hair
restoration surgery. This is a rapid loss of hair that occurs in the area of the
surgery, among hairs that are in the telogen, or resting stage. These hairs will
generally grow back, unless they are severely miniaturized hairs that would be
naturally lost within a short time anyway. Since it is not uncommon to be
placing incisions and FU’s between and around miniaturized hairs like these,
there can be significant loss. If large numbers of FU’s are placed during a
session, then at least the patient can know that the hairs that will grow in a
few months later will be strong, solid terminal hairs, and will compensate for
the effluvium loss.
One other rationale for large sessions considers the
need for different types of FU’s (i.e., singles, doubles, etc.). As we pointed
out in the section on mathematical planning, only a certain percentage of FU’s
will be single hair FU’s. This is quite important in planning the hairline
reconstruction, which required relatively high numbers of singles. If too few
FU’s are harvested, then the number of singles, for example, might fall short.
In this case, the only options are an incomplete hairline, or "creating" singles
by dividing 2 or 3 hair FU’s, which is definitely less than an ideal technique.
Indeed, if we claim the primacy of the follicular unit, how can we then
rationalize breaking them up? |
Insuring the Integrity of Follicular Units |
Let’s consider for a moment the other
techniques that we think are integral to the follicular unit transplantation
process. One is single strip harvesting, and the other is stereo-microscopic
dissection. Without these companion techniques, the procedure may be called
follicular unit transplantation, but it is a pale, inefficient imitation.
As
its name implies, single strip harvesting is the method by which a single strip
of hair-bearing scalp is carefully, indeed, painstakingly, excised from the
donor area; the strip is then broken down into its smallest functional units, or
follicular units. Before single strip harvesting came to the fore in recent
years, older, infinitely more wasteful methods were employed. The first of these
was the circular, punch grafts of yore, which have little to recommend them save
their simplicity (they are essentially biopsy punches), and the ease with which
they were directly placed into correspondingly circular holes in the recipient
area. Next, ingenious surgeons devised multi-bladed scalpels; three or more
(sometimes many more) blades, attached to a handle, were oriented parallel to
one another, and many thin, narrow, long strips could be excised with one pass
of the scalpel. These strips could then be placed flat on their sides and sliced
into small mini- and micro-grafts, with little or no concern for follicular unit
integrity. This, however, was not the only drawback; transaction rates were
generally rather high, and were even higher when more blades were used. So time
was saved, but lots of valuable follicles were wasted.
What we know as
single strip harvesting overcomes many of these disadvantages. Using two passes
with a single blade, or a single pass with a double-bladed knife, an elongated
strip is excised. It is possible, with careful technique, to achieve transaction
rates of less than 2% (this means that fewer than two FU’s per 100 are sliced in
two). It is estimated that transaction rates as high as 30% occur with the use
of multi-bladed scalpels. Let’s do the math. If the patient needs 1000 grafts,
then an area containing 1300 grafts would need to be removed just to account for
wastage and still produce 1000 intact FU’s. If 2000 grafts were needed, 600
would need to be wasted! This is of serious import when we deal with a limited,
finite amount of donor hair.
This leads us to a discussion of graft
dissection. One of the reasons many surgeons have used multiple strip harvesting
with multi-bladed scalpels, is that an intact, single strip presents a number of
difficulties in dissection. It is too thick to place on its side or to shine
light through (transilluminate) in order to visualize the individual FU’s.
Therefore, thin, multiple strips lend themselves to rapid, albeit inefficient,
slicing of grafts. We feel, however, that the degree of wastage is unacceptably
high, both during the strip harvest, and during graft preparation.
To avoid
these problems, the techniques of stereo-microscopic "slivering" and dissection
are utilized. As soon as the donor strip is harvested, the slivering process
begins. This is extremely painstaking; the strip is divided into small
"slivers", each one FU wide. These are then laid flat on their sides, and, also
under the microscope, the individual FU’s are carefully sliced out and trimmed
of excess connective tissue and fat. During this process, the grafts are
suspended in a physiologic saline solution and kept chilled; this insures their
viability and health while they are "out of body". They are separated into one,
two, three and four hair FU’s, according to their natural occurrence, and then
carefully placed into the recipient sites.
We feel strongly that follicular
unit transplantation is the state of the art in hair restoration surgery. Older
techniques are easier and more lucrative for the surgeon, require a smaller
operative team, and may be easier to "sell" with the false promise of higher
density. Follicular unit transplantation, done with single strip harvesting and
stereo-microscopic slivering and dissection, requires patience, a large team,
and meticulous work by the surgeon and assistants. Despite these demanding
criteria, we are committed to using and refining this technique; in one or two
sessions, patients can achieve results that are natural, undetectable, and will
stand the dual tests of time and of advancing baldness. |
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