Follicular Unit Grafting
To appreciate today’s hair transplant, one must realize how far we have traveled over the past 50 years:
When Dr. Norman Orentreich first introduced hair transplantation in the 1950s he was more interested in getting the hair to grow in its new site rather than concerned with the cosmetic appearance. The first hair transplants utilized a 4mm round punch which removed the hair and the surrounding tissue. This small piece of skin called a “plug” was then placed back into the scalp after a 3.5mm punch removed the bald skin. The bald skin was discarded and the “plug” was inserted in the new recipient site. The typical “plug” measured 4mm in diameter and had approximately 15-25 permanent hairs. To accommodate the blood supply in the recipient region, the “plugs” needed to be spaced one “plug” apart. This created the checkerboard effect which required 4 surgeries to fill in the entire transplanted area.
In 1984, Dr. Wayne Bradshaw, a hair transplant surgeon from Australia described a new approach to hair transplantation whereby a 4mm “plug” is either bisected (cut in half) or quadrisected (cut in quarters). Instead of removing bald tissue in the recipient region, a blade is used to incise or create a paper cut within the tissue. This new type of “plug” is called a minigraft. The term “plug” was then abandoned in hair transplant circles.
Dr. Emanuel Marritt advanced Bradshaw’s technique by cutting one hair or two hairs from the minigraft and coined the term micrograft. The micrograft was inserted into the skin after piercing the skin with a large bore needle (18 gauge needle).
As time went on, the harvesting of grafts with punches gave way to cutting an elliptical strip of skin which was closed by suturing the wound.
In the 1990s Dr. Bobby Limmer advanced the field of hair transplantation by acknowledging that hairs grow in discrete groupings of 1-4 hairs, and rarely 5 hairs. The term follicular unit was used to describe one, two, three, four and occasionally five terminal or mature hairs in addition to a discrete nerve and blood vessel supply, a connective tissue sheath, sebaceous gland, and an erector pili muscle. Dr. Limmer used a high powered binocular microscope to dissect the donor tissue into the natural hair grouping follicular units with the least follicular loss possible. Dr. Limmer believed that a natural hair transplant could be achieved by duplicating nature’s follicular units, rather than separating the units or bundling the units into groups. Follicular groups are composed of at least two or more follicular units.
Today, the donor hair is harvested by excising a narrow strip of tissue in the form of an ellipse from the back of the scalp where the follicles are resistant to hair loss.
The donor strip is then slivered or divided into very fine scalp sections measuring approximately 2mm in thickness utilizing stereoscopic dissecting microscopes.
A close look at these graft slivers demonstrate the natural grouping of follicular units.
The slivers are then dissected into individual follicular units using the stereoscopic microscope.
The microscope compared to magnifying loupes has been found to be more efficient in keeping the follicular units intact and resulting in less follicular transection. This process yields a higher number of intact follicular unit grafts from the available limited donor hair.
Once the follicular unit grafts have been meticulously prepared, a micrometer is used to measure the width of the hair shaft’s diameter. The length of the follicular unit graft is also measured in order to allow us to determine how deep the recipient site should be made to accommodate the graft.
After determining the width of the graft, custom made chisel blades are cut to perfectly match their size.
The length of the graft is then measured and carefully placed in a blade holder to match the length exactly. Since every person’s grafts measure a different length, we are duplicating nature and assuring the best cosmetic outcome.
By making recipient sites with custom blades, we are able to place the grafts closer together and reduce the possibility of vascular injury or trauma. In comparison to the 4mm “punch”, the typical chisel blade for a one hair follicular unit measures 0.7mm in diameter. The two hair and three hair follicular unit grafts usually measure 0.9mm-1.1mm in diameter.
We choose to produce custom-made chisel blades rather than the alternative sharp or spear point blades. The chisel blade produces a linear incision on the skin surface and a rectangular-shape beneath the skin surface. This allows an incision at right angles to the direction of hair growth. The spear point blades result in deeper incisions which could compromise or traumatize the vascular blood supply to the recipient region. The chisel blade allows us to dense pack the follicular unit grafts and achieves more optical density.
Once the donor tissue has been removed, the skin is sutured closed using a technique called the Trichophytic Closure. The trichophytic closure involves trimming the upper edge of the incision and then closing the wound so the hair near the edge that was trimmed can grow through the scar. This technique has been found to reduce the visibility of the scar and better camouflage the donor region.
The Lateral Slit or Coronal Angled Grafting:
Since the advent of minigrafts, hair transplant surgeons have made recipient slit sites parallel to the direction of hair growth.
Hairs in the donor region are naturally arranged next to each other in a plane perpendicular to the direction of hair growth. Placing the follicular unit grafts in a parallel or sagittal position creates unnaturalness and reduces optical density. By duplicating nature, making the recipient slits perpendicular to the direction of hair growth, we are returning the hair to the same distribution and alignment as in the donor region. This process is called the Lateral Slit Technique.
Advantages to the Lateral Slit Technique include:
- More precise angulation of the slits especially over the sideburns, posterior scalp and the lateral fringes.
- Reduced injury to the scalp blood vessels due to a shallower recipient site.
- Less graft popping since the force of incision is downward and upward, allowing free transmission of pressure to the outer surface of the scalp. This results in no pressure being applied to adjacent grafts.
- More optical density since the follicles lie side by side, rather than lined up behind one another. This results in the hair giving a thicker more natural appearance. The same number of grafts placed in a lateral or coronal angled slit visually makes the transplanted hair appear more dense and thicker than the parallel or sagittal angled slits.