Dear Gerard, Thank you. I will give a somewhat longer answer than I usually do in this informal chat because the issues you raise are important. I will answer all of your questions specifically, but first let me give you a little background. The importance of minimizing follicular transection was first scientifically addressed by Dr. Bobby Limmer in Texas, who began using a stereomicroscope in 1988. With the microscope, he was able to see significant amounts of dissection caused by punches and multi-bladed knives, damage that was unnoticed by gross visualization or with ordinary loop magnification. To solve this problem he developed the technique of single-strip harvesting, followed by stereo-microscopically controlled slivering, followed by stereo-microscopic controlled dissection of small mini-micrografts. When we published Follicular Transplantation in 1995, we were mainly concerned with keeping follicular units intact. The first thing we did was to greatly increasing the spacing of the blades on the multi bladed knife, the next was to use loop magnification for all aspects of the dissection, and the third was to build backlighting tables at all of our work stations to provide trans-illumination of the grafts, in order to increase visibility during dissection (This was the idea of Dr. Paul Rose). Unfortunately, none of these procedures were effective in keeping the units entirely intact. When we first heard of Dr. Limmer’s techniques (actually through the work of Dr. David Seager) it seemed obvious that this was the solution for both keeping follicular units intact, as well as avoiding follicular transection. We published a bilateral controlled study in Derm Surg the following year comparing the techniques and showed this indeed to be the case. The reason why single strip harvesting and stereo-microscopic dissection are more effective than other techniques in preventing follicular transection and keeping follicular units intact can best be understood if one divides all harvesting and dissection into two types of procedure, one that is performed “blind” and another performed under “direct visualization.” Blind harvesting and dissection would include situations where one is unable to see the entire length of the follicular structure during harvesting or dissection and/or when one is unable to surgically adjust for what is seen. Direct visualization would be defined as the situation in which the entire follicular structure can be seen and, equally important, when the technique allows the operator to adjust surgically to these visual cues to avoid follicular and follicular unit damage.

A goal of Follicular Unit Hair Tranplantation (FUT) is to minimize blind harvesting and perform as many parts of the harvesting and dissection under direct visualization. Whenever the initial incision into the donor area is made, it is a form of blind harvesting. Even when one removes a single ellipse, and the surgeon carefully (under magnification) observes the wound edge as he cuts, in order to follow the exact angle of the hair, there is some transection and splitting of follicular units. Fortunately it is extremely small. This has actually been measured by Dr. Limmer using stereo microscopy and is consistently around 1% (I think that this answers one of your questions). The idea behind single strip harvesting is that it keeps the area of tissue that is cut “blind” to an absolute minimum. To illustrate this point, lets take a typical 1,000-graft procedure. The strip would measure 1cm x 11cm. (The additional 1cm is to account for the fact that the ends are tapered into an ellipse). The 10cm2 would yield 1,000 follicular units, as there is 1 follicular unit per mm2 of donor tissue in the average Caucasian. The linear cut would thus be 22cm. There would be 1% damage in this “blind” part of the procedure, but then the strip is placed under a stereomicroscope and divided, via slivering, into large sections and placed in chilled Ringers Lactate. The “slivering” enables the dissector to go around follicular units with no transection. Once thin slivers are generated from the slivered sections, individual follicular unit dissection can proceed. With the donor tissue viewed under the stereomicroscope in vitro (out of the body), the strip literally becomes transparent and the structures of the unit stand out. With the microscope, a skilled dissector can readily avoid any follicular damage and keep follicular units intact. We have carefully studied (and published data on) the ability of our own staff to do this. To answer the concern about the donor strip drying. The donor strip is a large mass of tissue compared to an individual graft. Although a single graft may dry out in 2-5 minutes, the donor strip will not be impacted at all during this time period. Once the donor strip is removed, it is immediately placed in chilled Ringers lactate and only the section that is being dissected is kept out of the bath, not the whole strip. In addition, as we dissect, we have syringes of chilled Ringers that are used to keep the tissues constantly hydrated. The tissue is never allowed to dry. In our practice, donor wounds are sutured with Monocryl, a suture of low tissue reactivity that is absorbed by the hydrolysis (slowly broken down by the action of water). The sutures are placed within 1.5mm of the wound edge and spaced ½ cm apart so there is very minimal encroachment upon follicular units. We have recently published this technique. Contrast this to using a small 1.25mm punch (cylinder). For the same 1000 graft procedure, if one removed every other follicular unit, 20 sq cm of tissue would be involved (rather than the 10 cm with single strip harvesting). The length of the incision would be 1.25mm x 3.14 (pi) x 1000 grafts = 40 cm (rather than the 22cm with single strip harvesting). In addition, there would be 1000 wounds, albeit small, to heal by secondary intention (i.e. fill in with scar tissue) in contrast to almost none with the primary intention closure of single strip harvesting.

The issues regarding the use of small punches are not as simple as one would think. First, is the problem of blind harvesting that I mentioned. But, a much more important fact is that, although follicles are grouped in the upper portion of the skin (the dermis) into discrete follicular units, the bulbs of each follicle are random in the fat. This means that each follicle takes a curved, rather than straight, path through tissue. If one looks at this in three dimensions, the follicular unit looks much like a broom that is gathered at the top and splayed towards the end. Since the curves go in opposite directions, we (and others) have found it impossible to remove follicular units with small punches, and also capture all of the bulbs. (This is what I had alluded to in my first comments with the fiber optic technique we were using.) As a result, the transection rate with small punches exceeded 30% in our hands and we thus abandoned the technique. An additional problem is that the removal of one graft, and subsequent healing, distorts the adjacent grafts, making subsequent procedures more difficult. As a result, the person using a punch technique must extend well beyond the mid-portion of the donor zone for tissue. Even from the example I gave above, where every other follicular unit is removed, the donor width must be double what one needs with single strip harvesting. In repair cases with severe donor scarring, when a very tight scalp precludes a strip excision, small punch excisions have been used by a number of us to remove small amounts of donor hair. The risk of follicular transection is sometimes warranted in these cases, since the patient is left with few other surgical options. We all welcome solutions to the problems discussed above, but are not terribly impressed by unsubstantiated claims. The testimonials of patients, although very important, does not give real insight into a technique. Wasting of donor hair is rarely appreciated by the patient, especially early on, or when the balding is limited. The observation of doctors working under magnification gives little information about the ability to solve some of the problems I have mentioned. Speaking on behalf of Physicians in the ISHRS, and as a Contributing Editor of Dermatologic Surgery, I welcome any physician possessing special skills or techniques to share them with the scientific community at large, so every patient may benefit from this knowledge. Sincerely, Dr. Bernstein