Evidence-Based Hair Transplantation

Abstract

Hair transplantation is a permanent treatment option for androgenetic alopecia in suitable male and female patients. The best long-term outcome is achieved in medically or spontaneously stabilized hair loss. In these cases, the redistributed hair increases density and scalp coverage. Realistic expectations, a good donor-to-recipient area ratio, careful personal planning, and a skillful surgical team are essential. Follicular unit transplantation is the standard, involving dense placement of very large numbers of natural bundles of 1–4 hairs into recipient sites of appropriate size, angle, distribution, and direction. These transplanted hairs are virtually undetectable from the original hair. Thus, progressive alopecia is no longer a contraindication per se, if sufficient donor hair is available. The grafts are harvested with local anesthesia through strip excision with trichophytic closure to keep the scar minimal and/or by follicular unit extraction. Both harvesting methods have individual indications. Stereomicroscopic dissection with backlighting and the use of loupes for recipient site creation greatly reduce transection rates and temporary effluvium of preexisting hair. The hairline is created based on individual characteristics with micro- and macroirregularities, including a frontal transition zone of single hair units. More quantitative evidence from controlled trials is necessary to evaluate special techniques for each component of the procedure.