FUE Hair Transplantation: A Minimally Invasive Approach

© Springer International Publishing AG, part of Springer Nature 2019

Reza P. AzarFUE Hair Transplantationhttps://doi.org/10.1007/978-3-319-75901-2_1

1. History of Autologous Hair Transplantation

Reza P. Azar¹ 

(1)

Zentrum für Moderne Haartransplantation, Berlin, Germany

The first experiments with hair transplantation were performed in Würzburg, Germany, in the early nineteenth century. However, all the conventional procedures, the strip method, punch method, and FUE method, originated in Japan.

In the 1930s the Japanese physicians Okuda and Tamura began to perform autologous hair transplants. Okuda initially harvested the transplants using a classic biopsy punch and transplanted the hair-bearing skin islands into the recipient region and thus laid the groundwork for the punch method [1].

Tamura, however, employed a different procedure. He harvested transplants by excising skin which he later divided into small pieces and transplanted. In this way he became a forerunner of the strip method , also known as the FUT method [2].

The harvesting of individual follicular units (FUs) using a 1 mm cannulated needle was first described by the Japanese practitioner Masumi Inaba in 1988. This tissue-sparing procedure, described as follicular unit extraction (FUE) , remains to this day the only minimally invasive harvesting method in hair transplantation (Table 1.1).

Table 1.1

History of hair transplantation

The method described by Okuda for harvesting autologous grafts using a skin biopsy punch was adopted by the American physician Orentreich in the late 1950s. This is how autologous hair transplantation was first introduced into the Western world. Orentreich published his clinical results in connection with the treatment of patients with androgenetic hair loss and introduced the term donor dominance [3]. The term first described that the autologous hair follicle retains its healthy characteristics, namely, its insensitivity to dihydrotestosterone (DHT), after being transplanted to bald areas of the scalp affected by androgenetic alopecia. This means that the transplanted hair follicle will produce healthy hair even in a new location as its insensitivity to DHT is unaffected by androgenetic alopecia and will remain so in the future.

The cosmetically unsatisfactory and unnatural results of direct transplantation of hair-bearing skin islands 3.5–4 mm in size led to the development of new methods. Initially relatively large, the skin islands were dissected to ever smaller grafts. This division was performed without regard to the anatomy of the hair follicles growing in groups as follicular units. These hair groups were referred to as micrografts with 1–2 hairs and as minigrafts with 3–6 hairs.

Later the hair-bearing skin islands or skin strips were divided into differentiated anatomic units, follicular units, which increasingly led to superior clinical results compared with the earlier micrografts and minigrafts.

The cosmetically unnatural results of the punch method coupled with the relatively difficult procedure of dividing the harvested tissue into smaller grafts led many physicians to prefer the strip method of hair transplantation. Yet because of its traumatic nature and the resulting scarring, this method cannot represent a sustainable solution for androgenetic hair loss, a progressive condition.

From the mid-1990s on, the tissue-sparing technique of harvesting individual follicular units increasingly gained acceptance among physicians and especially among patients. This method of minimally invasive hair transplantation minimizes traumatization of the patient while maximizing cosmetic results by achieving a natural appearance. It may thus be regarded as the most promising method for the future.

References

1.

Okuda S. Clinical and experimental studies on transplanting of living hair (in Japanese) Jpn. J Dermatol. 1939;46:135–8.

2.

Tamura H. Pubic hair transplantation. Jpn J Dermatol. 1943;53:76.

3.

Orentreich N. Autografts in alopecias and other selected dermatologic conditions. Ann N Y Acad Sci. 1959;83:463–79.Crossref

4.

Headington JT. Microscopic anatomy of the human scalp. Arch Dermatol. 1984;120:449–56.Crossref

© Springer International Publishing AG, part of Springer Nature 2019

Reza P. AzarFUE Hair Transplantationhttps://doi.org/10.1007/978-3-319-75901-2_2

2. Fundamentals

Reza P. Azar¹ 

(1)

Zentrum für Moderne Haartransplantation, Berlin, Germany

2.1 Hair Restoration Surgery Terms

Understanding relationships in hair restoration surgery requires familiarity with a number of hair restoration surgery concepts which are explained in the following section.

For example, the anatomic distinction between a hair follicle and a follicular unit (FU) is of great significance in hair restoration surgery from the standpoint of surgical technique.

2.1.1 Hair Follicle (HF)

A hair follicle (HF) refers to one of the anatomically smallest and most complex human organs which is able to produce a single hair throughout life.

2.1.2 Follicular Unit (FU)

To avoid any terminological confusion, I would first like to point out that in this book I often abbreviate the anatomically correct term follicular unit as FU.

In contrast to the hair follicle (HF), the follicular unit is a functional unit that includes from one to four (rarely five) individual hair follicles and in this aggregate produces a corresponding number of hairs. Accordingly, a follicular unit (FU) can occur as a single unit comprising one hair follicle with one hair (1-hair FU) or in the form of a multiple unit combining two hair follicles with two hairs (2-hair FU) or three hair follicles with three hairs (3-hair FU) or four hair follicles with four hairs (4-hair FU). Very rarely it may also occur as an aggregate of five hair follicles with five hairs (5-hair FU) (Figs. 2.1 and 2.2).

Fig. 2.1

Occipital view of the hair fringe consisting of numerous follicular units (FU)

Fig. 2.2

View of the trimmed hairs in the occipital region of the hair fringe. 1 denotes a single unit (1-hair FU). 2 denotes a multiple unit (2-hair FU). 3 denotes a multiple unit (3-hair FU). 4 denotes a multiple unit (4-hair FU).

The FUs can be regarded as the building blocks of hair transplantation, which can be placed together in different combinations or placed individually to create a composition with a natural appearance.

2.1.3 Graft

This term comes from a time when hair surgeons did not yet have a deeper understanding of the structure of functional anatomic units. The term graft says nothing about the number of hair follicles included and as such is confusing and can also be used deceptively.

This is one example of deceptive use: A physician plans on using 1000 grafts for a hair transplant. To do this, he harvests 500 2-hair follicular units (2-hair FUs) and splits these functional units into 1000 grafts. Consequently, while the physician does indeed transplant the 1000 grafts promised, this is only half of the hair he would have transplanted had he transplanted 1000 2-hair FUs. As the patient is usually unaware of the distinction between graft and follicular unit, the term graft can be used in a confusing and deceptive manner. Therefore, the term follicular unit should be used instead of graft.

2.1.4 Minigraft and Micrograft

A micrograft contains 1–2 hairs.

A minigraft contains 3–6 hairs.

2.1.5 Hair Density (HD)

The hair density is specified as the number of hairs per cm².

2.1.6 Follicular Density (FD)

Follicular density (FD) is understood as the number of follicular units (FUs) per cm².

2.1.7 Hairs per Follicular Unit or Hair Count per Follicular Unit (HFU)

The number of hairs per follicular unit (HFU) specifies the average number of hairs per follicular unit.

2.1.8 Transplanted Follicular Density (TFD)

Transplanted follicular density (TFD) is understood as the number FUs per cm² after transplantation.

2.1.9 Extraction Quotient

The extraction quotient is the number of extracted FUs per cm².

2.1.10 Survival Rate

The survival rate provides information about the proportion of hairs that have survived after transplantation relative to the total number of hairs transplanted.

2.1.11 Donor Hairs

Occasionally the term donor hair is used. Depending on the context, it can refer to a hair follicle, a follicular unit, or all of the donor grafts considered as a whole (Figs. 2.3, 2.4, 2.5, 2.6, 2.7, 2.8, 2.9, and 2.10; Table 2.1).

Fig. 2.3

Follicular units after extraction from the occipital hair fringe

Fig. 2.4

Follicular units after extraction . From left to right: 1-hair, 2-hair, 3-hair, and 4-hair follicular units

Fig. 2.5

Microscopic view. Left: Individual extracted hair follicles. Right: Extracted follicular unit consisting of two hair follicles or two hairs

Fig. 2.6

Left: Microscopic image of a follicular unit with two hair follicles . Right: Longitudinal section through a hair follicle

Fig. 2.7

Histologic representation of the infundibulum of a hair follicle , defined as the section between the follicular opening on the surface of the skin and the opening of the sebaceous duct into the hair canal

Fig. 2.8

Histologic representation of the isthmus, defined as the section between the opening of the sebaceous duct into the hair canal and the insertion of the arrector pili muscle

Fig. 2.9

Histologic representation of the arrector pili in the isthmus and the hair bulb with the dermal papilla

Fig. 2.10

Hamilton-Norwood classification system for androgenetic hair loss in men

Table 2.1

Overview of important terms in hair restoration surgery

2.2 Hair Transplantation as a Surgical Procedure to Redistribute Healthy Hair Follicles

Hair transplantation is also referred to as hair restoration or hair grafting. To understand the procedure of hair transplantation, it is important to note that hair transplantation can only produce new hairs indirectly. Thus, hair transplantation is actually a redistribution of the healthy hair-producing follicles responsible for hair production.

Regardless of the various methods, which will be discussed in greater detail in the following section, each hair transplantation includes the following steps:

Extraction of the FUs

Temporary storage and processing of the FUs in a storage medium

Placement of the FUs or grafts

The fragile hair follicles are harvested from areas with healthy hair coverage (such as the back of the head, chest, or back) and then placed in previously prepared recipient sites at the desired location, where they continue to grow throughout the patient’s life. Thus, hair transplantation makes it possible to implant healthy hairs even in regions of the body affected by hair loss, where the implanted hairs can exhibit healthy, long-term growth.

However, hair transplantation is only possible with the patient’s own hair. This means that hair can be harvested and transplanted in a different location only in one and the same individual as the body would reject hair from another donor.

2.3 Androgenetic Alopecia (AGA) , the Most Common Form of Hair Loss

Given the high prevalence of androgenetic hair loss, we will discuss the etiology and pathogenesis of this androgen-induced, genetically determined, and age-dependent process in greater detail in the following section.

About 95% of all patients suffer from the symptoms of AGA, which is characterized by an increasingly shortened hair growth cycle and simultaneous miniaturization of the hair follicles in certain regions of the scalp.

As the name suggests, androgens play a crucial role in the development of this disorder especially in men. Hamilton [1] defined three decisive factors that determine androgenetic hair loss:

Genetics, androgen dependency, and age

He was the one who introduced the term androgenetic alopecia [1].

This type of genetically induced hair loss affects both men and women although there are typical sex-specific differences in the severity and progression of the disorder, which we will discuss below.

AGA was long thought to be an autosomal dominant disorder in men and an autosomal recessive disorder in women [2]. Kuster and Happle disproved this assumption in 1984 and documented the polygenetic inheritance pattern of AGA [3].

The logical consequence of this is to assume AGA is a complex disorder caused by several different gene variations or genetic defects and possibly other factors as well.

2.3.1 Androgenetic Alopecia in Men

Randall et al. demonstrated increased intracellular formation of androgen receptors in the areas of the scalp affected by hair loss [4].

Such androgen receptors in men usually decisively influence the differentiation of epithelial cells and the formation of terminal hairs. However, the increased number and thus the heightened activity of the androgen receptors lead here to an opposing effect characterized by the following symptoms:

Miniaturization of the hair follicles: the follicles shrink and produce thinner and shorter hairs.

Change in the physiologic growth phases: the anagen phase (growth phase) shortens, whereas the telogen phase (resting phase) lengthens [5].

2.3.1.1 Classification of Male Hair Loss

With few exceptions, AGA in men progresses with a typical pattern of hair loss. The Hamilton-Norwood classification system was introduced to facilitate comparability with respect to the degree of hair loss in men affected by AGA. According to this system, androgenetic hair loss in men is divided into different stages which are assigned to seven hair loss patterns (I through VII).

Although this classification fails to take individual patterns of hair loss and certain mixed forms into consideration, it does clearly visualize the possible manifestations of hair loss and permits standardized medical documentation. This classification has become an integral part of the routine clinical practice of modern hair restoration surgery.

The classification system received its name from Hamilton, who diagrammed the classification of the progression of male hair loss in 1951, and from Norwood, who modified and further developed the scheme in 1975 [6]. For practical reasons, we will refer to this joint classification in this book as the Norwood classification system and abbreviate it as NW.

2.3.1.2 Clinical Course of Androgenetic Hair Loss in Men

With few exceptions, AGA in men progresses with a typical pattern of hair loss.

Hair loss begins with bilateral frontotemporal balding, accompanied by thinning and receding of the anterior hairline (NW I–III).

The hair loss then extends over the vertex region (NW IV) and can progress to complete vertex