Depth control in follicular unit excision: A new classification from a detailed analysis of 30 patients undergoing FUE technique for hair restoration.

Abstract

In follicular unit excision (FUE), the concept of depth control (DC) has been created to minimize the risk of hair follicle damage. To analyze DC variation in different parts of the safe donor area of scalp; to propose Boaventura's new DC classification for hair restoration surgery using the FUE technique. Thirty male patients underwent hair restoration surgery. The donor area was distributed into 14 zones, with the minimum depth required for at least three atraumatic extractions of the grafts. When the extraction was not successful, 0.5 mm was added until reaching three follicular units, determining the DC area. Approximately 2000 extractions were performed on each patient to determine DC. For some areas, greater depth (2.54 ± 0.10 mm) was necessary. Fifty-eight percent of follicular units were extracted with 2.0 mm DC, and 3.8% required 3.5 mm DC. Thus, according to Boaventura's new classification for DC, grade I ≥ 2.00 mm, grade II from 2.1 to 3 mm, and grade III > 3.0 mm. There is variability in the DC of follicular units within the different areas of the safe donor zone. Moreover, we have proposed a new DC classification, which would represent a valuable estimation of surgery demand.