Robert M. Bernstein, MD, William R. Rassman, MD, Wojciech Szaniawski, MD,
Alan J. Halperin, MD
SUMMARY of Follicular Transplantation. International Journal of Aesthetic and Restorative Surgery 1995; 3(2):119-132.
Follicular Transplantation culminates more than 30 years of hair transplant evolution – from large plugs to the much smaller mini-micrografts. Its development, however, stems from a very simple insight: that hair does not grow singly, but rather in clusters made up of several hairs called follicular units. As with earlier procedures, the transplanted hair is taken from the “donor area” of the scalp, or the portion on the back of the head, to be transplanted into bald areas. But where the earlier surgical hair restoration procedures transplant “plugs” or “grafts” containing multiple follicular units along with their surrounding skin tissue, in follicular hair transplantation, the physician transplants only the follicular units, which have been dissected from the surrounding skin. The result is a less intrusive hair transplant procedure that promises far more natural-looking results. How? That’s what this paper will explore.
All the advantages of follicular transplantation stem from the fact that it is a hair restoration surgery procedure that moves hair just as it grows – in compact, naturally occurring groups of 1 to 4 hairs. Since there is a significant amount of bald scalp between follicular units, using only the natural units allows one to keep both the grafts and the sites that they are placed into as small as possible. The tiny wounds facilitate healing and insure that the recipient skin will continue to look normal.
Hair transplant surgery procedures that involve the transplantation of several follicular units at once – such as grafts and plugs – end up moving too much bald skin along with the follicles. Therefore, not only do the grafts look pluggy, but the underlying wounds are unnecessarily large and this leads to scarred skin, characteristically seen as coblestonning or bumpiness.
Plugs and large grafts can also lead to a noticeable contrast between the color of the transplanted hair and surrounding skin, due to the fact that these grafts produce scar tissue. At the same time, the excess tissue transplanted in plugs and grafts — tissue that tends to be much thicker and richer in sebaceous glands than tissue in bald scalp — often produces an abnormal-looking ridge underneath the transplanted hair. Another problem introduced by grafts and plugs is the interference with normal oxygenation and blood flow, threatening the hair implants long-term viability.
Follicular transplantation avoids these problems by minimizing the amount of tissue transplanted. The smaller the tissue mass of the graft, the easier it is for oxygen to reach the graft’s center and the better the growth. The tiny graft slits, meanwhile, are made with a needle-like instrument, keeping trauma at the site to a minimum. Just as importantly, because there is less accompanying tissue to transplant, hair restoration surgeons performing follicular transplantation have much more flexibility in placing the transplanted hair, allowing for remarkable cosmetic advantages. Hair units can be transplanted extremely close together, for instance, and placed in a natural pattern.
Follicular transplantation limits the size of the wound where the hair implants are inserted to just a slit, about 1-mm wide, much smaller than with the earlier procedures. The day after surgery, patients are able to shower and shampoo the transplanted area to remove any crusting.
In Follicular Unit Hair Transplantation, far more grafts can be placed per session, which is beneficial not only for surgical reasons, but also for the convenience of the hair transplant patient. Medically, it makes sense for the surgeon to transplant as much hair as possible in the first session in order to take advantage of the normal blood flow and collagen in a “virgin” scalp. It is also easier for the surgeon to plan the larger-scale patterning and positioning of the grafts without worrying about constraints arising from previous hair implants. Another consideration is that, each time the donor area is harvested, a small number of follicles lying along the edge of the wound are destroyed.
With respect to the patient, smaller sessions simply drag out the hair restoration process. More than an inconvenience, enduring multiple sessions can become extremely discouraging to those anxious for results.
The Procedure – Harvesting the Hair
In hair transplantation, the hair to be transplanted comes from the region in the back of the scalp known as the “permanent zone,” where balding rarely takes place. There are several factors that the hair transplant surgeon must consider when determining how much hair can be harvested. The surgeon must determine the density of the hair in the donor area as well as the patient’s scalp laxity. Scalp laxity is very important to note, as overlooking this point can leave the scalp too tight after closing the wound.
The density should be measured with a magnifying instrument called a densitometer during the patient’s initial consultation and again just before the procedure. A hair restoration doctor can get a good sense of scalp laxity just by moving the scalp in the permanent zone and noting the contour of the underlying cranial bones. The mid-portion of the donor incision should lie approximately over the occipital protuberance – the prominent bony ridge in the back of the head where the donor hair is most dense and most stable.
Measurements of donor density, miniaturization, and scalp laxity are essential not just for optimal planning of the procedure about to take place, but also for projecting patients’ long-term surgical hair restoration needs.
Having determined the donor supply, the hair transplant surgeon then has to appropriately size the donor strip and estimate the amount of hair it will yield. Factors to be considered – in addition to donor supply, density and laxity – include how many grafts are needed for different regions of the scalp, the estimated number of hairs in each follicular unit and the effects of any previous transplant incisions. The incision is made at least 1 cm below the lowest possible line of potential hair loss, which ensures that the scar will be covered. On each end, the incision should also stay at least 1 cm above the top of the ear, while the surgeon should account for the possibility of recession along the temples as well. Scars from earlier hair implants can be incorporated within the new donor strip if they are noticeable or if the strip will yield sufficient hair and there is sufficient laxity in the area to remove it. But if the previous scar is considered to be either too high or too low, or if there is too little laxity, the hair transplant surgeon will generally leave it be. Most often, surgeons will choose to run the top or bottom incision of their new strip alongside the old scar, thereby limiting the unavoidable follicle damage to only one edge of the incision. The donor strips can be excised at varying widths and lengths, but the depth should be just slightly deeper than the follicles, to avoid damaging the root of the follicles and the larger nerves and blood vessels below. The wound is then sewn up with sutures that are usually left in place for two weeks.
Next, the strip must be dissected. In short, this means the follicular units have to be identified and then removed intact from the donor tissue with just enough surrounding tissue to make sure they are not damaged in the process. They must be handled with utmost care to protect against their warming and drying. In light of such challenges, there is no substitute for a highly experienced and motivated staff.
The hair restoration doctor must know precisely how many 1-, 2- 3- and 4-hair units the strip will yield in order to place the grafts optimally in the recipient area, and yet the surgeon cannot wait until all the dissections are finished because such a delay would endanger the follicular units dissected first. The dissecting team is, therefore, instructed to project the harvest on the basis of random samples of the dissected strip, so that transplanting the hair can begin while the dissection is still in progress.
Placing the Grafts
At no stage in the hair transplantation is the surgeon’s skill and experience more essential than in deciding where exactly to place the grafts and how to angle them. A number of considerations should guide these determinations, chief among them the importance of replicating the pattern of hair growth set by nature and of plotting a natural distribution of follicular units. But the surgeon should also concentrate on “framing the face” and creating a natural hairline. Adding coverage to the crown is generally a secondary goal during the surgical hair restoration procedure. It is also important to avoid contrast between areas of the scalp as much as possible and to ensure that the transplanted hair will grow at natural angles. None of this can be accomplished without an accurate assessment of the hair transplant patients’ pattern of hair loss and prospects for eventual balding, along with an understanding of their donor supply and specific hair characteristics, such as the degree of wave, hair-shaft thickness and the contrast between the skin and hair color.
With knowledge of each patient’s hair demand and supply, the surgeon can replicate the best hair-growth pattern possible – given the demand and supply – as it appears in nature. While adhering to these patterns, however, it is possible to place the grafts in a way that creates a fuller look by striving to frame the face, or bring the patient’s facial features back in proportion. This can be achieved by locating the frontal hairline about one fingerbreadth – approx. 2 cm – above the uppermost brow wrinkle. Placing the hairline lower, i.e. trying to restore the patient’s adolescent hairline, not only demands more follicular units but also risks creating an unbalanced look as the patient matures.
The judicious hair restoration doctor will often choose not to fill in the crown area, or allot just a small share of the grafts for this purpose, since the back of the scalp generally affects the patient’s overall appearance the least. This allows more density to be added to areas considered more important cosmetically. Because the crown tends to be the largest balding area, transplanting it can use up large amounts of the donor supply and reduce the availability of hair for hair implants. Moreover, it is the least stable of the balding areas. As the hair loss radiates outward, it is especially challenging to keep up with this hair loss while conserving hair for future balding in other more cosmetically important areas of the scalp.
At the same time hair transplant surgeons need to take care to avoid any contrast between different parts of the scalp and to make sure to angle the grafts to grow in a natural direction. Typically, balding patterns with the greatest contrast between hair-bearing and bald scalp cause the greatest distress in patients. Lessening this contrast diminishes the appearance of baldness. It is also helpful in creating a natural look to have the grafts evenly spaced in a random pattern, rather than a uniform grid. With regard to angling the grafts, surgeons often can rely on vestigial hairs in the recipient area for a model, but this can be deceptive since the fine vellus hair is often oriented radially.
In general, the hair on the top of the head points forward, not upward, though the angle becomes more radial at the temples. With follicular transplantation, the hair transplant surgeon is able to precisely control the angle of the grafts.
What Happens Next
Though follicular transplantation represents the state of the art in hair transplantation at this point in time, there are certainly more advances to be expected. A number of innovations still under development hold promise for fine-tuning pre- and post-op assessments, streamlining the procedure and reducing the need for a linear incision.
High-resolution video-imaging, for instance, should allow surgeons to take far more accurate hair counts, assess hair implants for physical damage and better understand graft survival and yield. And ultra-pulsed CO2 laser systems could prove a valuable tool for rapidly applying a large number of uniform graft slits, though as they function today they suffer from the drawbacks of causing too much scarring and sealing off blood flow to the graft.
One of the most hotly anticipated advances in surgical hair restoration has to be the prospect of cloning hair follicles, which would create an unlimited supply of grafts – from a relatively small donor supply. For all its promise, however, the technology of cloning remains in its infancy. An advance far more likely to bear fruit in the short term is the development of automated instrumentation. As practiced today, follicular transplantation is a meticulous, extremely labor-intensive procedure, both for the surgeon and the staff. But instruments now under development seem certain to lessen this burden by simplifying everything from the harvesting of the donor strip to the placing of the grafts.