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Hair Transplant

Follicular Unit Hair Transplantation

Robert M Bernstein MD, New York, NY

PUBLISHERS NOTE: Single copies of this article can be downloaded and printed only for the reader’s personal research and study.

In: Robinson JK, Hanke CW, Siegel DM, Sengelmann RD, editors: Surgery of the Skin, Chapter 34. Elsevier Mosby Inc., London UK. 2005: 549-574.

Summary Box

• Follicular Unit Transplantation (FUT) is a method of hair restoration surgery that relocates hair in follicular units, its naturally occurring groupings. The small size of the units allows for tremendous versatility in their placement, the creation of hair patterns closely mimicking nature and transplant procedures large enough that a full restoration can often be achieved in just two sessions.

• Since FUT requires large numbers of grafts, it is important to accurately assess patients’ donor reserves in the initial planning. Densitometry enables the hair transplant surgeon to estimate the total number of movable hairs, the size of the individual follicular units and the degree of miniaturization in both the donor and recipient areas. Scalp laxity assessment is also crucial to the surgical planning.

• Great care should be taken to screen for surgical hair restoration patients who are too young or whose hair loss may be diffuse and involve the donor area.

• Identifying androgenetic alopecia often proves more difficult in women as other medical conditions must be considered. Options for medical treatment options are more limited in female patients and many experience diffuse hair loss, a relative contra-indication to hair transplant surgery.

• Determining the right size and location of the donor strip prevents problems such as widened and/or visible scars. The follicular units obtained from donor strips are delicate structures. Careful dissection, gentle handling and adequate hydration are essential to their survival.

• In order to dissect and place the thousands of grafts often required in FUT, the surgical hair restoration team must be proficient in stereo-microscopic dissection and inserting techniques – skills that can take a year or more to develop.

• Follicular Unit Transplantation requires an astute aesthetic sense for optimal hairline design, correct angling and distribution of grafts and the establishment of a master plan that anticipates further hair loss and is consistent with the long-term goals of the patient.


Within the past decade, Follicular Unit Transplantation (FUT) has transformed hair transplantation from a cosmetically unpredictable procedure to one that can produce consistently natural results. The key to its effectiveness lies in the fact that scalp hair tends to grow in tiny bundles, called “follicular units,” rather than individually.1 By working with these naturally occurring units, instead of larger or smaller grafts, FUT creates as natural a look as possible while minimizing the transplant wound size and accelerating post-operative healing. A recently developed refinement, Follicular Unit Extraction, promises to eliminate, for select candidates, the procedure’s most invasive aspect: the surgical removal of a strip of tissue from which the units are harvested.2

Follicular units are made up of one to four terminal hairs, one to two vellus hairs, their associated sebaceous glands, neurovascular plexus, an erector pilorum muscle, and a circumferential band of adventitial collagen, the perifolliculum.3 The tendency of scalp hair to grow in this way, rather than in single hairs, can be most easily demonstrated by clipping the hair to approximately 1 mm in length and then viewing it with a densitometer at x 30 magnification in a 10-mm field.4 What this also reveals is that these compact units are surrounded by significant amounts of non-hair-bearing scalp.5 Including this extra skin in the dissection — as do hair transplants with larger grafts, such as plugs and minigrafts — requires a larger recipient wound, as well as risking visible scarring in the skin around the grafts and distortions of the growing hair.

In FUT, these naturally occurring units are used exclusively. The FUT procedure takes advantage of the anatomic proximity of the hairs within each unit to: 1) keep the recipient site wound size to a minimum, 2) virtually eliminate any skin surface change in the recipient area, 3) facilitate post-op healing, 4) enable grafts to be placed very close together and 5) permit large numbers of grafts to be safely transplanted in a single session (because of the small recipient wound size).1,6 The ability to insert up to four hairs in a tiny recipient site is especially valuable cosmetically and has been instrumental in eliminating the see-through quality of micrografting. In the end, what this means is that the transplanted hair will look natural, as long as the hair transplant surgeon makes the right aesthetic decisions about graft placement, angling and distribution.7,8

The higher precision of FUT as compared to mini-micrografting is especially obvious when methods of harvesting the grafts are compared. In FUT, once a strip of donor tissue has been removed, follicular units are taken out intact through careful stereo-microscopic dissection, avoiding injury to the follicles.9,10,11 The grafts in mini-micrografting, on the other hand, may or may not correspond to individual follicular units. They are cut from the donor strip according to the number of hairs they contain (optimally one to six, but often more) and/or the size of tissue required to fit into a given recipient site, a process known as ‘grafts cut-to-size’. Often the dissection is performed without magnification, and it is also common for the donor tissue to be removed with a multi-bladed knife, rather than as a single strip, causing significant destruction of follicles. Because the grafts may be too large to fit into a slit incision, an excision (where recipient tissue is removed, such as with a small punch) is sometimes needed. In contrast, the recipient sites used for FUT always consist of small incisional slits.

In a new hair restoration procedure called Follicular Unit Extraction (FUE)2 the need for a donor strip is eliminated entirely. In this procedure, individual follicular units are removed (extracted) directly from the donor area through a small circular incision with, or without, micro-dissection. Although this procedure obviates the need for a linear strip, it has limitations, particularly in the inability to efficiently utilize all the tissue in the mid-portion of the permanent zone. As of this writing, most hair transplant surgeons performing FUE have used it for select patients only. A brief description of this procedure will be included in the section on the donor harvest under Techniques [cross ref].

The purpose of this chapter is to elaborate on the basic technical skills and aesthetic judgments involved in FUT. It should be taken as a framework for physicians interested in learning the procedure, not an exhaustive review of the various surgical techniques used in FUT or of other surgical hair restoration methods. The chapter will not cover mini-micrografting, which is still widely practiced,12 the combining of large and small grafts,13 laser hair transplantation,14,15 scalp reductions,16,17 scalp lifts,18 or flaps.19 These procedures have been detailed in many excellent publications, as well as in two comprehensive textbooks.20,12

When learning FUT, the importance of hands-on experience and beginning with small sessions until ones’ skills develop cannot be overemphasized. Having a well-trained team of assistants is also important to a successful outcome, particularly for those procedures involving a large number of grafts.

Although simple in concept, FUT has many nuances and complexities. Those wishing to perform FUT in their clinical practice are encouraged to join the International Society of Hair Restoration Surgery (ISHRS) and attend its annual meeting, subscribe to Hair Transplant Forum International (the trade publication for hair transplant surgeons), and follow relevant medical literature (particularly Dermatologic Surgery). Although it is not an accredited board, certification by the American Board of Hair Restoration Surgery (ABHRS) indicates a basic competency in the field and requires three years of clinical experience and passing both oral and written examinations. The process of preparing for ABHRS certification is a worthwhile endeavor and recommended for those serious about surgical hair restoration.

Historical Vignette

Reports of successful hair transplants appeared as early as 1930 in Japanese literature, beginning with Sasagawa’s hair-shaft insertion procedure21 and then Okuda’s success in pioneering 2- to 4-mm punches for the treatment of various alopecias of the scalp, eyebrows and moustache. Okuda made the important observation that using smaller punches in the recipient area improved cosmetic results.22

By 1943, Tamura had treated 137 cases of non-androgenetic alopecia of various etiologies using techniques very similar to modern-day hair transplantation.23 For instance, he harvested donor grafts by making an elliptical incision that was sutured closed, prepared recipient sites with a thick needle, stored grafts in physiologic saline, and observed post-operative telogen effluvium. Most significantly, Tamura demonstrated that single-hair grafting resulted in growth practically indistinguishable from naturally grown hair–and much more natural-looking than hair transplants using larger grafts. But it took several decades before Western surgeons would apply Tamura’s insights to their hair restoration procedures.

The first hair transplant surgery in the United States was performed by Dr. Norman Orentreich in 1952 with grafts measuring 6 to 8 mm in diameter,24 significantly larger than those of either Tamura or Okuda. At first, incredulous editors rejected Orentreich’s work, not believing that hair transplantation was even possible. He finally found a publisher in 1959, in the Annals of the New York Academy of Science. The paper laid out the concept of “donor dominance”–the idea that grafts continue to show the characteristics of the donor site after they have been transplanted to a new site. This remains the basic tenet of all hair transplantation surgery. Yet while donor dominance insured that transplanted hair could grow, it did not guarantee that the results would look natural.

Not until 40 years later would hair transplants in the United States start to produce consistently natural-looking results and promise predictable cosmetic improvements in most patients. It was a slow evolution, but the large grafts used throughout the sixties and seventies eventually gave way to minigrafts in the eighties4 and mini-micrografting in the early nineties.25 The stage was then set for Follicular Unit Transplantation. First appearing in the medical literature in 19951 it quickly emerged as the standard in hair restoration–supplanting mini-micrografting in the treatment of androgenetic alopecia and rendering other well-established procedures such as scalp reductions, scalp lifts and flaps virtually obsolete.

So swift was FUT’s ascent that the two standard textbooks on surgical hair restoration, published in 199520 and 199612, as well as the most comprehensive text on trichology, published in 1997,26 make not one mention of the terms “follicular unit” or “Follicular Unit Transplantation.” At the 1996 meeting of the International Society of Hair Restoration Surgeons, three seven-minute presentations on the procedure were given; but at the 2002 meeting, FUT was the subject of entire seminars and workshops and suffused every aspect of the weeklong gathering.

The follicular unit was first defined by Headington in his landmark 1984 paper “Transverse Microscopic Anatomy of the Human Scalp.”3 Follicular Unit Transplantation had its origins in the microscopic dissection techniques of Dr. Limmer in 1988 that was described in his paper “Elliptical Donor Stereoscopically Assisted Micrografting as an Approach to Further Refinement in Hair Transplantation” in 1994.9 The term “follicular unit” was introduced into the hair transplant literature by Bernstein and Rassman in 1995. The conceptual framework for FUT was mapped out by these authors in the publication “Follicular Transplantation”1 and in the paired articles, “Follicular Transplantation: Patient Evaluation and Surgical Planning” and “The Aesthetics of Follicular Transplantation” (1997).7,8

The name “Follicular Unit Transplantation” was formalized by a group of hair restoration surgeons in a 1998 publication in Dermatologic Surgery.10 In this paper, the procedure was precisely defined and included the two basic techniques, single-strip harvesting and stereo-microscopic dissection, as integral parts of the procedure. However, since follicular units can now be harvested directly from the donor area without the necessity of a strip incision (using Follicular Unit Extraction2) the original definition has become too restrictive.

The term Follicular Unit Transplantation should now be used to encompass all hair restoration procedures that utilize naturally occurring, individual follicular units exclusively in the surgery, regardless of how these units are harvested. The caveat, of course, is that the harvesting technique must always maintain the follicular unit’s integrity.


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Follicular Unit Hair Transplantation
Follicular Unit Hair Transplantation
Surgery of the Skin; 1(Chapter 34) (2005) 549-574



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