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STATE OF THE ART SURGICAL TECHNIQUE: FOLLICULAR UNIT HAIR GRAFTING

Author: Jeffrey S. Epstein, M.D., F.A.C.S.
Clinical Professor, University of Miami
Private Practice, Miami, FL
305.666.1774
305.666.6708 (fax)
[email protected]
Send all reprint requests to Dr. Epstein: 6280 Sunset Drive, Suite 504, Miami, FL 33143
Presented at the AAFPRS International Meeting, New York, NY, May, 2002

Word count: 2,884

INTRODUCTION:
The goal in hair restoration is natural appearing results. Improvements in the field of hair transplantation have developed with this goal in mind. The most recent development is the follicular unit grafting technique, which relies upon microscopic dissection to produce grafts each containing a follicular unit, the natural bundling of 1 to 4 hairs, with a minimal amount of non-hair-bearing surrounding skin. For patients desiring surgical hair restoration, proponents of follicular unit grafting advocate the technique's superior results. Detractors point to the technical challenges of performing the procedure, with the need for a staff of trained assistants for the microscopic dissection. What is clear is that this demanding procedure is taking the field of hair restoration the closest to its ultimate goal- undetectability.

TEXT:
The earliest techniques of hair transplantation, as developed half a century ago, utilized unaesthetic plug grafts, 4 mm circles of hair-bearing scalp containing as many as 20 hairs. (1,2) Over the latter half of the 20th century, the size of the grafts became smaller and smaller, in an attempt to approximate the way hair grows naturally on the scalp. Thus, the large plug graft became the hemi-dissected semicircle graft, then onto the quarter graft, and continued to be made smaller and smaller.(3-6)

Unlike those that preceded it, the micro/minigrafting technique, popularized in the early 1990s, has come close to accomplishing the goal of undetectability.(7,8) With this technique, currently utilized by the majority of hair transplant surgeons, micrografts containing 1 or 2 hairs are placed along the hairline, while the remaining areas are transplanted with minigrafts containing 3 to 5 hairs.

Over the past several years, follicular unit grafting has emerged as the most reliable technique for natural appearing results.(9,10) The follicular unit graft consists of a single follicular unit, the way hair grows in the scalp- in tiny bundles of 1 to 4, most commonly 2 and 3 hairs. First described histologically by Headington in 1984, the follicular unit consists of these terminal hairs, surrounded by an adventitial sheath, in which is also contained the sebaceous gland elements and other supporting tissue.(11) The dissection of these individual grafts is performed under a microscope, permitting the excision of all excess non-hair bearing tissue.(12,13)

Transplanting exclusively with these follicular unit grafts theoretically creates the most natural appearing hair restoration. Of course, the follicular unit is merely the building block; a natural appearing result is attained through proper hairline design and other aesthetic considerations.

The dissection and subsequent placement of as many as 3,000 follicular units is a demanding process, utilizing a team of experienced assistants. Proponents of this procedure feel that the extra time and expense required is justified by the improved results and other several significant advantages. Microscopic dissection results in grafts that are smaller, containing a minimum of scalp skin. These grafts can be placed into smaller recipient sites, theoretically allowing for greater hair density, faster healing, and less trauma to already existing hairs in the recipient area. In addition, transplanting grafts with a smaller "cuff" of skin minimizes changes in pigmentation and texture of the recipient scalp. Microscopic dissection of the donor hairs minimizes accidental transection and subsequent demise, with studies confirming as much as a 20% increase in hair yield.(14) Finally, another advantage of microscopic visualization is the ability to accurately identify and separate grafts according to the number of hairs each one contains. Thus, when a 1 hair graft is placed along the anterior-most hairline, only 1 hair, not 2 or even 3 hairs, will grow.

SURGICAL TECHNIQUE
Pre-operative consultation is critical for educating the patient about the progressive nature of male pattern baldness, and for establishing a treatment plan. The number of grafts to be transplanted in a procedure typically ranges from 1600 to 2200, but can go higher or lower, depending upon the demand (amount of bald or thinning scalp that the patient desires to be filled) and the supply of available donor hairs. Patients are advised that, while an acceptable density can be achieved with just 1 procedure for the majority of patients, with progression of hair loss it is likely that a second procedure will be desired in the future.

Most procedures are performed under oral sedation. Hairline design, while beyond the scope of this discussion, is critical for achieving a natural result. With the patient's feedback, the future hairline is marked out; this line will serve as a template for what will be the location of the hairline, which is not a line but rather a broken, irregular transition zone. The administration of local anesthetic to the donor and recipient sites is currently facilitated by the use of The Wand®. This computer-controlled anesthetic injection system permits the administration of anesthetic agent at a slow, controlled rate that is at or just below the threshold level of sensation.

Under sterile conditions, the fusiform-shaped single donor strip is excised from the occipital scalp in the subcutaneous plane just deep to the follicles. The size of the strip is determined by the number of grafts to be transplanted. The density of hairs in the donor region of the scalp typically ranges from 70 to 120 follicular units per cm2, with a median of 80. Therefore, in the typical patient, a 20 cm2 (20 cm in length by 1 cm in width) sized donor strip would be required for a 1600 graft procedure. The donor site defect is closed primarily with a single running 3-0 Prolene suture (Ethicon, New Jersey).

A team of highly trained assistants dissects the grafts from the donor strip. Using the binocular microscope, the single strip is subdivided into thin slivers 2 to 3 follicular units wide. These individual slivers are then further dissected into individual follicular units, excising all surrounding non-hair bearing scalp tissue (see Figure 1 for illustration). The grafts are kept in chilled saline until the time of implantation, separated by hair number. The mean number of hairs per graft is 2.2 to 2.3, with most grafts containing 2 or 3 hairs.

The making of recipient sites is probably the single most important step in assuring a natural result. Critical factors include proper direction of growth, varying density of graft placement, and the irregularity of hair placement along the hairline. The surgeon must make the recipient sites keeping these variables in mind, while minimizing the transection of any existing hairs in the area. For making the recipient sites, a variety of instruments are available; the author prefers the Sharp Point® blades (Ellis Instruments, New Jersey) for their sharpness and size. The 15 degree, 22.5 degree, 30 degree, and occasionally the 45 degree Sharp Point are used for recipient sites for 1 and small 2 hair grafts, larger 2 hair grafts, 3 and small 4 hair grafts, and 4 hair grafts, respectively.

The placement of the grafts into the recipient sites is performed as atraumatically as possible. Jeweler's forceps are the ideal instrument for this purpose. Attention to details, such as using the finest single hair grafts along the front of the hairline, and inserting each graft such that any natural curvature of growth of its hair(s) complements the surgically created recipient site angle, reinforces a natural appearing result. Graft placement is the final step in the hair transplant procedure.

A procedure typically takes 4 to 6 hours to perform, depending upon the number of grafts transplanted. The patient leaves the office bandage-free, and usually returns the next day to have the hair washed. Light exercise and careful hair washing can be resumed on the third day, with full resumption of physical activity permitted at one week. Typically the tiny crusts around the grafts fall off by 7 days, and the donor site sutures are removed at 8 to 10 days.

Like with other forms of hair grafting, the transplanted hairs go through a telogen effluvium stage, falling out by the 3 weeks. As soon as 8 to 10 weeks later (if the patient applies minoxidil to the scalp post procedure), and continuing for the next 4 months, the hairs start to regrow, then continue to do so as hair does elsewhere in the scalp. If desired, a subsequent procedure can be performed as soon as 3 to 4 months later.

Results

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