Chapter 8 – Follicular Unit Transplantation
Follicular Unit Transplantation is the technique that has revolutionized modern hair restoration surgery. It has given hair transplant surgeons the ability to restore a person’s hair in just one or two sessions and to produce results that, when done properly, can look completely natural. This procedure, first described by Bernstein and Rassman in their 1995 paper “Follicular Transplantation” and detailed in over 50 subsequent publications, is now used by virtually every physician performing hair transplants today.
The idea of Follicular Unit Transplantation (FUT) is simple. Since hair grows in small groups of 1-4 hairs per group, in Follicular Unit Transplantation, hair is transplanted exactly this way. By mimicking the way hair grows in nature, the surgeon has the ability to produce results that will look totally natural. This “ability” to produce great results, however, is no guarantee that these results will be achieved and in Follicular Unit Transplantation, the artistry of the surgeon and the skill of the surgical team are critical to realizing the procedure’s full potential. When poorly executed, FUT offers little advantage over older hair restoration techniques.
The conceptual simplicity of FUT belies the many important benefits of this procedure. Other advantages of the technique include; the ability to safely perform large hair transplant procedures involving thousands of grafts, the potential to complete the restoration in just a few sessions, very rapid healing, and the maximum utilization of a patient’s donor hair supply. This chapter will explain the basic ideas behind Follicular Unit Transplantation and how they benefit patients undergoing hair restoration procedures. It will also describe some of the import aspects of this procedure, so that patient’s will know what to expect (and demand) when considering this type of surgery.
What Exactly are Follicular Units?
Follicular Units are the functional hair bearing structures of the skin. On the surface of the scalp they are seen as tiny groups of hair that appear to be growing together. Viewed under a microscope, they are seen as well-demarcated structures. Although follicular units had been described by the histologist Headington in 1984, their existence had gone unrecognized by hair restoration surgeons. (See chapter 7, Hair Transplant Basics)
In the human scalp, follicular units are comprised of individual groups of 1-4 terminal hairs. In addition to the normally thick, terminal hairs, follicular units also contain 1-2 tiny vellus hairs, sebaceous (oil) glands, a small muscle, small nerves, blood vessels, and a thin band of collagen that surrounds the unit called the perifolliculum.
The follicular unit determines most of the important characteristics of one’s hair including hair thickness, color, texture, curl, orientation on the scalp, growth rate and susceptibility to DHT. In areas of the scalp affected by androgenetic balding, the effects of DHT cause healthy, thick, terminal hairs that comprise follicular units, to gradually be replaced by hairs of shorter length and smaller diameter in a process called “miniaturization”. Over time the effects of DHT will cause follicular units susceptible to this hormone to disappear. (See Chapter 4, Hereditary Baldness.)
What is Follicular Unit Transplantation?
In Follicular Unit Transplantation, hair is removed from the permanent zone in the back and sides of a person’s scalp, dissected into naturally occurring, individual follicular units and then transplanted into the areas affected by the balding process. In contrast to other forms of hair transplantation, where grafts may contain varying numbers of hairs depending upon the whim of the surgeon, in FUT, the graft is the follicular unit. Therefore, a follicular unit graft contains exactly the number of hairs that the follicular unit contained and it is exactly the same size.
In order to remove follicular units from the back of the scalp without damaging them, the donor tissue must be removed in one piece. This technique called, “single strip harvesting,” is an essential component of Follicular Unit Transplantation as it not only preserves the follicular units, but also prevents damage (transection) to the individual hair follicles. It is a significant advance over the older minigrafting and micrografting techniques that used multiple bladed knives to remove the donor tissue, as these instruments broke up follicular units and caused unacceptable degrees of damage to hair follicles.
Another essential component of Follicular Unit Transplantation is “stereo-microscopic dissection.” In this technique, the follicular units are removed from the donor tissue under microscopic control to avoid damage. Complete stereo-microscopic dissection techniques have been shown to produce an increased hair yield as high as 30% over other methods of graft production. Since all patients have donor supplies that are limited, the preservation of every follicle is a critical aspect of the technique.
However, the procedure of Follicular Unit Transplantation, as detailed in Bernstein and Rassman’s landmark publications on the subject, is more than just a refined technique of graft harvesting and dissection. It is a philosophy of hair transplantation that directs the surgeon to carefully consider the needs of the patient and then, within the constraints of the patient’s actual donor supply, to devise a realistic, long-term plan that can best meet his or her goals.
The ambitious nature of this procedure is stated in the introduction to the authors’ original publication on Follicular Unit Transplantation. It reads:
Follicular Transplantation is the logical end point of over 30 years of evolution in hair restoration surgery, beginning with the traditional large plugs and culminating in the movement of one, two and three hair units, which mirror the way hair grows in nature. The key to follicular transplantation is to identify the patient’s natural hair groupings, dissect the follicular units from the surrounding skin, and place these units in the recipient site in a density and distribution appropriate for a mature individual.
The critical elements of follicular transplantation are an accurate estimation of the donor supply of hair, meticulous dissection of the follicular units, careful design of the recipient area to maximize the cosmetic impact of the hair transplant, the use of large numbers of implants in fewer rather than more sessions, a long-term master plan that accounts for the progression of the male pattern alopecia, and realistic expectations on the part of the patient.
Bernstein and Rassman, 1995
All of these elements need to be considered by the physician if the patient is to have the maximum benefit of the FUT procedure. The physician’s medical judgment, his artistic sense, his surgical skills and the experience and abilities of the entire surgical team are important in making this very labor-intensive hair restoration procedure a success.
The Reasons for Transplanting Follicular Units
The main reason for transplanting follicular units is to be able to produce completely natural results. This is possible because the follicular unit grafts themselves represent the way hair grows in nature – in tiny groups of 1 to 4 hairs each. If grafts smaller than follicular units are used, the results will look too thin. If one transplants groups larger than follicular units, the hair will look clumpy and uneven. When the doctor uses follicular units exclusively in the hair restoration, the hair transplant can be undetectable.
Just the use of follicular units, however, does not ensure that the hair transplant will look natural. Other aspects of the procedure must still be done properly; such as meticulous graft dissection, making the recipient sites the right depth, placing the grafts in the appropriate distribution, angling them in the right direction, as well as a host of important nuances in technique.
The follicular unit is a physiologic entity, rather than just an anatomic one. It is more than a tiny bundle of hair. It is a living structure, complete with nerves, blood vessels and a protective collagen sheath. When follicular units are transplanted intact, the surrounding tissue serves to protect them from drying and from mechanical injury during the placing process. It has been observed that when hair grafts were obtained by breaking up the naturally occurring follicular units, their growth was less than when the follicular units were kept intact. Keeping the structure whole, will increase the chance that all of the hair in the follicular unit will grow.
As we discussed, when individual follicles are cut (transected), their survival decreases dramatically. Besides, keeping the follicular units intact, the stereo-microscopic technique of follicular unit transplantation insures that the individual hairs that comprise each unit will be preserved during the process of graft dissection. Therefore, using FUT techniques serves to protect both the follicular unit and the hair follicles that comprise them – insuring maximum growth of the transplanted grafts.
Creating Small Wounds
Using follicular units is the best way to get the most hair into the smallest possible recipient sites (the holes in the skin that the grafts are placed into). Small recipient sites are important for a number of reasons; First, the small wounds facilitate rapid healing; second, the small wounds cause less damage to skin in the recipient area, so that graft growth will be maximized; third, if the recipient sites are small, they can be placed closer together, allowing the grafts to be packed more densely; fourth, small wounds create a snug fit for the grafts; fifth, small wounds cause less interference with the underling blood supply, which in turn allows more grafts to be transplanted in one session.
The above diagram illustrates why follicular units allow the surgeon to place the most hair in the smallest possible recipient sites and still look natural. On the left is a 3-hair graft that was made using the old mini-micrograft technique that literally cut up the donor strip into small pieces, ignoring the fact that hair grew in natural groups. Note that the graft on the left is comprised of a 2-hair group and a single-hair, separated by a bit of bald scalp. Because it contains extra tissue, this 3-hair graft measures 1.5mm and, therefore, must be placed in a recipient site at least this wide.
In contrast, the graft on the right consists of a 3-hair follicular unit measuring only 1mm in diameter and allowing it to fit into a much smaller hole (while still containing the same amount of hair). This may not seem like a big difference, but when multiplied over thousands of grafts (and their corresponding smaller sites) the effects on the rapidity of healing, graft growth, and maintaining the scalp’s normal blood flow is substantial. In addition, whereas a wound of 1.5mm may leave a permanent mark on the surface of the scalp, a wound of 1-mm never does (a 1mm incision is about the width of the needle used to draw blood from your arm).
Once a doctor tries to use grafts that are larger than a person’s naturally occurring follicular units, the extra tissue contained in the grafts will necessarily increase the size of the wounds, impede healing and risk looking unnatural. This unnatural look is due to the fact that hair may look tufted and uneven when it grows and may produce pigmentation changes and scarring on the skin’s surface. In addition, when larger grafts are used, the grafts may either elevate or heal with a slight depression, further altering the surface of the skin. The key to a natural appearing hair transplant is always to have the hair emerge from perfectly normal looking scalp. The only way to ensure this is to keep the recipient wounds small.
If the surgeon goes in the other direction and divides up follicular units (either through poor dissection techniques or by design) he is not increasing the total amount of hair transplanted; he is just unnecessarily increasing the number of grafts and the number of recipient sites that are needed to hold them. This increases the amount of wounding to the scalp, risks injury to the grafts from the splitting of follicular units and, of course, increases the cost of the procedure, when doctors charge by the graft. In fact, splitting up follicular units allows fewer hairs to be placed in a defined area of the scalp and results in a thinner look.
Using follicular units, therefore, allows the surgeon to transplant the greatest amount of hair with the smallest wounds and with the least trauma to the scalp. This maximizes healing and facilitates growth. It also creates the fullest look to the restoration while insuring the naturalness of the hair transplant.
A final important advantage of the small wound is a factor that can be referred to as the “snug fit.” In order to place a large graft into a recipient site, when using older techniques, a small amount of tissue needed to be removed so that the graft could fit. This was typically accomplished with a small instrument called a “punch” that, in the process of cutting out tissue, destroyed the local elasticity of the skin and loosened the scalp’s hold on the graft. In contrast, a follicular unit graft is so small that it can always fit into a very small wound, without having to remove tissue. A small incision, made with a needle, retains the basic elasticity (recoil) of the recipient site. When a properly fitted follicular unit is inserted into the scalp, the recipient site will hold it snugly in place.
This “snug fit” has several advantages. During surgery, it minimizes graft elevation (popping) and the need for the sometimes traumatic re-insertion or re-positioning of grafts. After the procedure, it ensures maximum contact of the graft with the surrounding tissue, so that oxygenation can be quickly re-established. This facilitates healing and graft growth. In addition, by allowing the tissue to hold the graft firmly in place the “snug-fit” enables the patient to shower and gently shampoo the scalp the day after the hair transplant. This allows the person to resume his daily routine as quickly as possible, without the procedure being detectable.
Large Hair Transplant Sessions
An important consequence of the follicular unit’s ability to be inserted into very small recipient sites, and to thus minimize wounding to the scalp, is to give the surgeon the ability to be able to safely transplant large numbers of grafts in a single hair transplant session. This, in turn, allows the hair transplant process to be completed as quickly as possible. Of course, we do not mean rushing the patient to surgery, but rather completing the transplant in as few sessions as possible, so that there is less interference with a person’s lifestyle.
The Advantage of Performing Large Sessions
Although large hair transplant sessions are made possible by the ability of follicular units to fit into very small recipient sites and to minimize wounding, one might ask what the actual advantage is for doing this. It is an important question, since large sessions are time consuming, require a larger surgical team, and are more costly for the patient (at least per procedure). There are a number of very important reasons.
The specific reasons that a person with hair loss seeks treatment may vary, but the common denominator of those undergoing surgical hair restoration is the hope that enhancing their appearance will improve the quality of their life; be it personal, social or professional. There is probably no better way for a surgeon to undermine this goal than to subject an already self-conscious patient to a protracted course of small, incomplete procedures. The disruptions from the scheduling of multiple surgeries, the limitations in activity, and the concern about their discovery, can place a patient’s life “on hold.”
Until the restoration is finished, the patient will be conscious of the process and will find it difficult to move forward.
The physician should, therefore, try to accomplish the restoration as quickly, and in as few sessions, as possible. Even more important, is that each procedure should stand on its own, so that after one procedure the results will look natural and, if more than one procedure is planned, the patient can still continue with normal activities while awaiting the next session.
Account for Shedding
In genetic hair loss, full-thickness terminal hairs gradually decrease in length and diameter through a process called miniaturization. Miniaturization is a universal aspect of androgenetic alopecia and accounts for most of the early changes that we see. In other words, in the early stages of hair loss, the “thinning” that one notes is actually due to thinning (i.e. miniaturization) of the hair shafts, rather than the actual loss of hair itself.
Regardless of the surgeon’s technique, an inevitable aspect of hair transplant surgery is that the patient’s existing hair in, and around, the transplanted area has a chance of being shed as a result of the procedure. The hair that is at greatest risk of being lost is the hair that has already begun the process of miniaturization and, if this hair is at, or near the end of its normal life span, it may not return. The medical term for this shedding is telogen effluvium. It is also referred to as shock hair loss.
Often this shedding is mild and insignificant, but at times is can be substantial. The reason is that in some patients, especially those in active stages of hair loss, large amounts of hair can be undergoing this process of miniaturization. Thus, identifying those patients especially at risk, explaining to all patients that some shedding may occur and planning for it surgically, are import aspects of the hair restoration process.
The risk of shedding can be lessened by using small recipient sites and limiting their depth, reducing the amount of epinephrine (adrenaline) used in the anesthesia, and minimizing the tension on the donor closure. However, regardless of the “claims” of a particular surgeon, the process is a natural response of hair follicles and the risk can not be eliminated entirely.
To plan for a possible effluvium surgically, the physician should consider the following:
1. Defer surgery to those who are very early in the balding process, i.e. those who are content with the way they look now, but are more concerned about future hair loss. A good rule of thumb is to wait until the patient needs a minimum of approximately 800 follicular units before considering surgery. Often medical therapy, rather than surgery, would be appropriate for these patients.
2. When considering surgery, carefully define the boundaries to be transplanted by gross visual inspection, as well as with the densitometer (a more sensitive indicator of miniaturization).
3. Transplant through, rather than avoiding, an area that is highly miniaturized, since it is likely that this area will be lost by the time the transplant has grown in.
4. Plan to use enough follicular unit grafts so that, if possible, the volume of transplanted hair is greater than the volume of hair that might be lost from telogen effluvium. Remember, we are never replacing “hair for hair” in the surgery. We are replacing a large number of fine, miniaturized hairs, with a much smaller amount of permanent, full-thickness terminal hairs. In areas of extensive miniaturization, it may be appropriate to transplant follicular units in the same density as one would if the area was totally bald.
Economizing the Donor Supply
The finite nature of the donor supply is the ultimate limiting factor in all hair restoration surgery. As we have discussed, proper harvesting techniques and precise follicular unit graft dissection is critical to ensuring maximum donor yield. Using a smaller number of larger transplant sessions, rather than multiple, small sessions, will also help to maximize this supply.
Each time an incision is made in the donor area, and each time sutures are placed, hair follicles are damaged or destroyed. This damage can be minimized, by keeping the sutures close to the wound edges so that they don’t encompass much hair and/or removing them soon after the procedure in non-tension closures. Staples, in particular, may minimize damage to surrounding hair follicles and conserve donor hair. However, regardless of how impeccable the technique, each surgical procedure is associated with some degree of hair wastage.
There are other more subtle effects of the surgery. In the healing process, collagen is laid down and reorganized. This distorts the direction of the hair follicles and increases the risk of transection in subsequent procedures. As we will discuss, this is a very significant problem with Follicular Unit Extraction (FUE), but also had some relevance to Follicular Unit Transplantation. In addition, the fibrosis makes the scalp less mobile for subsequent surgeries, thus decreasing the amount of additional donor tissue that can be harvested. With each hair restoration these factors come into play, so that transplanting in large sessions, which minimizes the total number of individual procedures, will maximize the total amount of donor hair available.
Enhancement of Graft Sorting
A final advantage of using large numbers of follicular units in the hair transplant session is that it permits graft sorting, an important technique that can enhance the cosmetic benefit of the procedure.
Unlike, the older procedure of mini-micrografting, where the doctor cut grafts to what ever size he desired (much to the cosmetic determent of the patient), in follicular unit transplantation, the follicular unit is the graft. Therefore, in a person who has mainly 1- and 2- hair follicular units, the resulting dissection will yield mainly 1- and 2- hair grafts. In contrast, a person with higher density will have a greater population of 3- and 4-hair units and thus more of these grafts.
Although this anatomic characteristic of the patient can not be changed, different size units serve different purposes, and the surgeon musts have a sufficient number of each to maximize his craft.
The cardinal principle in designing a hair transplant is to duplicate natural hair patterns. In most adults, the frontal, forelock area has greater density than the hair adjacent to this. This central frontal density gives the person a masculine look and can easily be differentiated from the diffuse thinning seen in genetic hair loss or in disease. Two of the tools the surgeon can use to create this central density are to place grafts closer together in this central area and to use larger follicular units (graft sorting).
The limitation of transplanting grafts too close together is that, if placed too close, the wounds may impede the blood supply and graft growth. In fact, the dense packing technique used by most physicians with expertise in FUT, already maximizes the close graft placement of grafts, so that there is uniformly closely placed grafts over the entire area to be transplanted. This leaves graft sorting as the other means to create natural density gradients. Graft sorting is simply using follicular units of different sizes for different purposes, so in this case larger follicular units (those of 3- and 4-hairs) would be placed into the forelock area to create greater density in this area. It should be obvious that when performing transplant with a greater total number of follicular units, graft sorting becomes a more powerful technique.
Another critical aspect of the hair transplant is to make the fontal hairline soft and natural. To accomplish this, the surgeon needs a significant number of 1-hair grafts – generally on the order of 250. In small sessions, there may not be enough naturally occurring 1-hair follicular unit grafts obtained fro the donor strip to accomplish this goal, leaving the surgeon with the only choice of dividing up larger grafts. This will not only increased the risk of graft injury and poor growth but will compromise the other goal of the transplant, namely creating adequate density.
The following example illustrates how the use of larger numbers of grafts per session can increase the power of graft sorting. The table below shows the number of follicular unit grafts obtained from a person with an average of 2.3 hairs per follicular unit in his donor area. The person has a Norwood Class 4a pattern of hair loss, which means that he has lost his frontal hairline and most of the hair in the front part of his scalp. The chart compares the number of each type of follicular unit that would be obtained in a 1,000 graft hair transplant session with the number of follicular unit grafts in a 2,000 graft session.
With a 1,000 graft session, there are only 400 follicular units available to be used in the forelock area, too few grafts to create any significant density in a patient with Class 4a hair loss. A 2,000 graft session in this patient, however, would yield 800 3- and 4- hair grafts, a sufficient number to create a nice central forelock with the remaining 1200 grafts to create a hairline and fill in the remainder of the frontal area.
One could argue that you could perform a 1,000 graft procedure and then just repeat it a year later. However, you then encounter the inefficiencies and wastage of multiple sessions as described above and, of course, the inconvenience to the patient by postponing the completion of the restoration for an additional year.
The other problem is that when the procedure is performed in two sessions, there would not be enough single hair grafts in a 1000 graft case to complete the frontal hairline. In our example patient, with a donor density of 2.3 hairs per follicular unit, only 200 1-hair grafts would be generated (approximately 50 to 150 grafts short of the 250-350 grafts normally needed to create a soft frontal hairline. The patient would than need to wait until the next procedure before the hairline was completed. The alternate strategy, dividing up 2-, 3-, or 4- hair units to generate the single-hair grafts, would risk injury to the follicles and would result in a decrease in the size and/or number of the remaining grafts.
In sum, when using larger sessions, the greater numbers of 3- and 4-hair units will provide the “natural resources” to create significant fullness in select areas and a sufficient number of 1-hair grafts will allow the creation of soft, natural hairlines. Therefore, another reason for using larger procedures is that they will offer the surgeon the greatest flexibility in designing the transplant, without having to combine or split follicular units.
How is Follicular Unit Transplantation Different from Mini-Micrografting?
This is one of the most commonly asked questions and it is a very important one for those deciding which hair restoration procedure to choose. In contrast to Follicular Unit Transplantation, where the graft sizes are determined by nature, in mini-micrografting, the combination of minigrafts and micrografts, (see Chapter 7, Hair Transplant Basics) the graft sizes are arbitrarily determined by the doctor who cuts the donor tissue into the size pieces that he wants. Another name for this technique is mini-micrografts “cut to size.”
In mini-micrografting, neither preserving follicular units, nor even keeping hair follicles intact, are felt to be that important. Rather, the speed and economics of the procedure are the deciding factors. Doctors performing mini-micrografting use a multi-bladed knife to quickly make thin strips of tissue and then use direct visualization (rather than microscopic control) to cut the tissue into grafts. The resulting grafts are generally larger than follicular units and, since the excess skin is not trimmed away, the donor sites (wounds) are larger as well.
It should be apparent from the comparison shown on the next page that Follicular Unit Transplantation is superior in producing a natural, undetectable result, in maximizing healing, and preserving precious donor hair. Mini-micrografting, however, requires a smaller staff and each procedure is cheaper and shorter (although in the end it takes more procedures and therefore may cost just as much for this technique).
The following table summarizes the major differences between Follicular Unit Transplantation and Mini-Micrografting:
|Follicular Unit Transplant||Mini-Micrografting|
|Follicular Units Only||Yes||No|
|Graft size||Uniformly small||Larger|
|Number of hairs per graft||1-4||1-6 (or more)|
|Hair/skin ratio in graft||High||Average|
|Extra skin transplanted||Yes||No|
|Wound size||Uniformly small||Variable|
|Harvesting type||Single-Strip||Multi-bladed knife|
|Follicular Units Preserved||Yes||No|
|Maximizes donor supply||Yes||No|
|Skin surface change||No||Yes|
|COST & CONVENIENCE|
|Duration of procedure||Long||Short|
|Time for full restoration||Short||Long|
|Cost per procedure||More||Less|
|Total cost for restoration||Similar||Similar|
Continue reading this hair transplant book:
Chapter 9 – Follicular Unit Extraction »»
Table of Contents
|Chapter 1||Brief History of Hair|
|Chapter 2||Hair and Its Functions|
|Chapter 3||Causes of Hair Loss|
|Chapter 4||Hereditary Baldness|
|Chapter 5||Psychology of Hair Loss|
|Chapter 6||Hair Loss Medications|
|Chapter 7||Hair Transplant Basics|
|Chapter 8||Follicular Unit Transplantation|
|Chapter 9||Follicular Unit Extraction|
|Chapter 10||Master Plan for Restoring Hair|
|Chapter 11||Goals and Expectations|
|Chapter 12||Numbers of Grafts Needed|
|Chapter 13||Hair Transplant Repair|
|Chapter 14||Hair Loss in Women|
|Chapter 15||Hair Systems and Camouflage|
|Chapter 16||Preparing for a Hair Transplant|
|Chapter 17||The Hair Restoration Procedure|
|Chapter 18||What to Expect Following Surgery|
|Chapter 19||Hair Transplant Fallacies|
|Chapter 20||Choosing Your Doctor|
|A Final Note|
|About the Author|