Hair transplantation surgery has evolved radically since its introduction in the German literature by Dieffenbach in the early nineteenth century. Since that time, from the first report of successful punch graft transplantation for alopecia by Okuda in the 1930s, to Norman Orentreich's use of larger 6–8 mm punch grafts and his description of the concept of donor site dominance in the 1950s, to the definition of the follicular unit by Headington and the development of follicular unit transplantation by Limmer and its subsequent championing by Bernstein and Rassman in the 1990s, the field has trended towards developing techniques that achieve more natural-appearing and esthetic end-results [1–5]. Alternate techniques such as scalp reduction and scalp flaps have been described but they have become largely obsolete because outcomes that were too frequently esthetically unpleasing. Developing an evidence-based approach to hair restoration surgery is difficult, however, because most hair restoration techniques have been described in case series, anecdotal reports, position papers, and colloquium guidelines, and have not been compared in large, prospective, randomized controlled trials .
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