Hair transplantation: A review and technique presentation

Abstract

Androgenic alopecia is an aesthetic concern that affects a large percentage of the population. Recent refinements in hair transplantation have allowed for more natural and predictable results. In this article, a review of the topic is presented, and a technique for hair restoration is described. One of the most common cosmetic surgical procedures performed on the male patient is hair replacement. Because the frontal hairline serves to frame the face, its loss can have a dramatic effect on a patient’s appearance and self-image. Hair transplantation techniques are now able to predictably recreate the hairline and thinning scalp hair, thus restoring the vertical thirds required for aesthetic facial balance. However, to successfully achieve natural results in hair replacement surgery, one must fully understand the process, progression, and various patterns of alopecia. Only with this knowledge in hand is the surgeon able to accurately evaluate patient expectations and design a treatment plan to achieve satisfactory long-term results. Hair growth occurs in 3 phases. The anagen, or growth phase, involves active growth and elongation of the hair follicle and shaft. This is followed by the catagen phase, in which there is a cessation of cell division and involution of the follicle. Finally, the hair enters the telogen, or resting phase, in which the life cycle is completed as a new hair develops from an anagen follicle, dislodging the overlying telogen hair. In the unaffected person, this process continues throughout life, with the number of hairs shed essentially equaling the number of hairs formed. 1 However, in persons with androgenic alopecia (AGA), there is a progressive shortening of the anagen growth phase and a subsequent decrease in the number of actively growing hair follicles, and thus a more rapid progression to follicular miniaturization. 2 Both of these factors lead to an overall decrease in the actual and apparent scalp hair density. Although the exact mechanisms underlying AGA still have not been clearly delineated, various studies have pointed to the necessity for a genetic predisposition as well as the local presence of male steroid sex hormones (androgens). Hamilton 3 was one of the first to document the interplay of these 2 factors in the development of AGA. In observing castrated persons, he noted that after castration they did not suffer from further hair loss. When he subsequently administered exogenous testosterone to these patients, he found that some, but not all, experienced alopecia. The role of testosterone in AGA now appears to be only as a precursor for the more potent androgen dihydrotestosterone (DHT). DHT is converted from testosterone by 5a-reductase in various tissues throughout the body, including the hair shaft. The potency of this androgen