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The Science Behind Hair Transplant Surgery


Dr. Rawnsley’s mastery of the most precise hair transplant techniques including Follicular Unit Transplantation and Saline supertumescence, which he helped to pioneer, and his visual artistry, based in his experience as a facial plastic surgeon, place him at the leading edge of Hair Restoration surgeons.

Overview of Follicular Unit Transplantation

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Follicular Unit Transplantation (FUT) gives the fullest, most natural head of hair. In FUT, hair is harvested from a donor area at the back of the head where hair is generally unaffected by male pattern baldness. These donor grafts are dissected into individual follicular units, which are the smallest natural groupings of 1-4 hairs and their accompanying support system. The follicular units are precisely placed into tiny, closely packed recipient sites where hair is thinning. Done artfully, with attention paid to the angle, depth, and hair patterns, follicular unit transplantation is the most effective, natural appearing and undetectable hair restoration technique available.

The process begins by selecting the donor area. It’s exact location and size depend on the number of grafts necessary and the characteristics of the patient’s scalp, but can generally be thought of as a thin band at the back of the head. Using the Strip Method, a thin strip of hair is precisely removed from this area. This strip is processed by a team of dissectors using high magnification to remove all of the non-hair bearing tissue. From the one strip they will produce hundreds or a thousand or more individual follicular units. During the dissection the recipient sites in the balding area are being prepared. Super-fine slits are made in a specific pattern to mimic natural hair density and placement. Each follicular unit is placed one at a time into its recipient site with careful attention paid to its angle and depth.

There are many advantages to Follicular Unit Transplantation. The process has become so refined that there is minimal scaring in the donor area and no visible marks left in the recipient area after healing. It allows for the precise placing of individual follicular units and, in the hands of a skilled surgeon, results in the natural growth patterns that appear on our heads.

What about FUE or Follicular Unit Extraction?

FUE is the method of removing the individual follicular units from the donor area directly rather than removing a strip and then dissecting into follicular units. This technique is still in it’s early stages of development and is not recommended for most patients. FUE intrinsically damages a much higher percentage of hair follicles which means more must be harvested to achieve the same density. Additionally, and a factor important to patients who are eager to get back to work shortly after surgery, FUE requires the shaving of the whole head. With Strip Harvesting only the thin donor area is shaved and this can be easily camouflaged by the surrounding hair. Of course, Follicular Unit Extraction can be useful to some patients with specific requirements. During consultation, Dr. Rawnsley assesses each patient’s individual needs and selects a course accordingly.

Donor Area

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The donor area is a band at the back and sides of the scalp where the hair is genetically programmed not to fall out. This area lies above the occipital protuberance (the bump at the back of the head) and extends like a headband to either side.

Saline Tumescence

Dr Rawnsley is one the first surgeons in the U.S. to adopt the use of Saline Supertumescence (also known as scalp dilation) and has since become a pioneer of the procedure, achieving outstanding results for over a decade. After first being locally anesthetized, saline is injected between the layers of skin in the scalp causing it to gently expand. By separating the layer with the hair follicles from the the deeper tissue, Dr. Rawnsley is able to remove the donor strip using a very shallow incision. Additionally, scalp dilation helps reduce bleeding, as pressure is kept on the capillaries. After the surgery, the body naturally absorbs the saline.


The donor area is carefully closed using the trychophytic (“tricho”) method with absorbable sutures. Sutures offer the surgeon better control of the wound edges and are more comfortable for the patient.

In a Trichophytic closure, the initial incision is made parallel to the hair follicles and then the tissue is trimmed away 1 to 3 mm above or below the wound edge so that the top of the hair follicles can be removed. Then the trimmed wound edge is pulled towards the opposite edge to cause the bottom of the hair follicle to point towards the incision instead of parallel. This causes the hair to actually grow through the thin scar, further diminishing its visibility.

Dissection of Tissue

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A dedicated and highly trained team of dissectors, under Dr Rawnsley’s guidance, dissect the donor strip into the follicular units. The dissection team works in the procedure room, during the procedure, to ensure the highest level of results in the shortest amount of surgical time.

Dissection Process

The donor strip is first separated into sections by slicing through the non-hair bearing tissue around the hair follicles. This first step, known as “slivering,” creates rough sections 2 – 2.5mm wide.

The non-hair bearing tissue (made up of excess dermis and fat) is then trimmed away by the dissector to isolate the individual follicular units.

The follicular units are grouped according to number of hairs. Each will have 1 – 4, depending on the number hairs that naturally occur.

Once the follicular units have been isolated and organized into groups they are placed in a special solution and refrigerated. They are kept at 40 degrees Fahrenheit to keep the tissue healthy and ready for transplantation.

As the recipient sites are created, groups of follicular units are removed from refrigeration and are prepared for placement by increasing their temperature to 59 degrees until placement onto the scalp.

Recipient Sites

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The recipient sites are created by making very short, needle-thin slits in the recipient area. This method gives the surgeon the utmost aesthetic control over the direction and angle of the hair growth. This is particularly important in the highly visible areas of the temple, crown, sideburns and eye brows.

Using fine hypodermic needles the recipient sites are made as small and as close together as possible. This minimizes the chance of scarring and enhances the amount of oxygen going to the graft, which reduces the healing time. The incisions’ depth is calculated precisely in order to avoid damaging the deeper blood vessels of the scalp.

The density and spacing of the recipient sites depends on a number of factors, including: desired density of hair; area to be covered; amount of donor units; size of follicular units; and the ability of the scalp to support the grafts, which is dependent on health and skin quality factors.


Feathering is a follicular unit placement technique used by Dr. Rawnsley that mimics the natural density and placement of hair. In doing this, Dr. Rawnsley reproduces the microvariations of the native hairline, giving it a visually soft appearance, rather than a harsh rigid linear look that can occur with less focused restorations. Fine, single hair grafts are placed at the front of the hairline. 2- and 3-hair follicular units are inserted behind these fine hairs to give more density. Then a mix of follicular units is used throughout the rest of the area as needed to match the natural growth pattern. Generally, the grafts are placed more closely together towards the front of the scalp and farther apart moving backwards as naturally occurs.

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