Commentary by Robert M. Bernstein, M.D., New York, NY
Dermatologic Surgery 1998; 24: 929-932.
After observing literally thousands of patient’s scalps through the densitometer (that was originally designed to simply measure hair density), Dr. Rassman and I came upon the idea of building the entire transplant around the exclusive use of individual follicular units. This was approximately the same time we were exploring transplanting in very large sessions. I thought that using individual follicular units seemed to be the ideal way to minimize total wounding in these larger procedures (initially performed, by the way, with a multi-bladed knife and loop magnification), and it would address the issue of the “thin look” seen with extensive micrografting, since each graft could contain more hair and still fit into a very small site. In addition, not only were these naturally occurring groups distinct, but their spacing in the scalp seemed to be relatively constant and practically independent of the density of the patient’s hair.
The idea of a follicular constant added simplicity to the surgical planning as pretty much the same number of grafts would be needed to cover a given area regardless of the patient’s hair density. The size of the donor harvest could simply be calculated, since the spacing of the follicular units was relatively constant (at 1 per mm2). In addition, follicular units could be “sorted” according to size in order to maximize the cosmetic impact of the transplant. For example, those containing 3 and 4 hairs might be placed in the forelock region for greater density and the smaller units in the transition zones. Most importantly, this sorting allowed us to increase hair density in certain areas without having to make the sites closer together. Sessions involving larger numbers of grafts had the additional benefit of generating more units of each size that could be used for these aesthetic decisions.
A more subtle revelation was that patients with only a few hairs per follicular unit would have a thinner look and this would be an essential characteristic of their transplant, since combining these units would not produce more hair, but only significantly increase wound size. At the other end of the spectrum, patients with greater numbers of hair per follicular unit could have dramatic results from a single session, given that their other hair characteristics were also favorable. These issues have the greatest significance in subsequent transplant sessions, and their understanding would be needed for setting realistic goals and for appropriate long-term planning.
We called this procedure, which involved the movement of large numbers of individual follicular units into very small recipient sites “Follicular Transplantation” and published it in 1995 in the Journal of Aesthetic and Restorative Surgery. The article, besides defining the follicular unit, and stressing the importance of very small wounding, discussed practical and aesthetic issues to be considered when these implants were transplanted in large sessions.
The following is the abstract of that original paper:
ABSTRACT: Follicular Transplantation is a method of hair restoration surgery which recognizes the follicular unit as the basic element of tissue to be moved in the transplant. The anatomic and physiologic basis of this procedure, as well as its potential advantages, is discussed. We then describe in detail how follicular implants may be used in extensive quantities for the treatment of androgenetic alopecia.
Bernstein RM, Rassman WR, Szaniawski W, Halperin A: Follicular Transplantation. International Journal of Aesthetic and Restorative Surgery 1995; 3:119-132.
Dr. Halperin mentioned that Dr. John Headington, a dermatopathologist at the University of Michigan had done extensive work with horizontal scalp sections. I spoke with Dr. Headington about our project and he sent me an article that he had written in 1984 entitled, “Transverse microscopic anatomy of the human scalp.” To my surprise, not only had Headington defined the follicular unit histologically, but noted the same follicular unit constant that we had observed clinically. Clearly, he is responsible for originating the term “follicular unit” back in 1984.
I first presented the 1995 “Follicular Transplantation” paper at the 1996 ISHRS in Nashville. At that same meeting, Dr. David Seager gave two pivotal presentations “Does the Size of the Graft Matter?” in which he showed that intact follicular units actually grew better than when they were split, and “Dissection with binocular stereoscopic dissecting microscope” in which he ran a video displaying, in vivid detail, the technique that he had learned from Dr. Limmer. As a result of this meeting the concept of follicular unit transplantation was launched, and the impressive nature of microscopic dissection was illustrated to hair transplant surgeons from around the world.
