Follicular Unit Extraction (2002): Summary

Follicular Unit Extraction: Summary

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Minimally Invasive Surgery for Hair Transplantation

William R. Rassman, MD*, Robert M. Bernstein, MD*,**, Robert McClellan, MD*, Roy Jones, MD*, Eugene Worton, MD*, Hendrik Uyttendaele, MD, PHD**

Dermatologic Surgery 2002; 28: 720-728.

*New Hair Institute Medical Group, A Professional Corporation, Los Angeles, California and **Department of Dermatology, Columbia University, College of Physicians and Surgeons, New York, New York


Follicular Unit Transplantation (FUT) is performed using large numbers of naturally occurring, individual follicular units obtained by single-strip harvesting and stereo-microscopic dissection. Donor wound scarring from strip excision, although an infrequent complication still concerns enough patients that an alternative solution is warranted.


The purpose of this paper is to introduce Follicular Unit Extraction (The FOX Procedure) in which individual follicular units are removed directly from the donor region through very small punch excisions, and to describe a test (The FOX Test) that determines which patients are candidates for this procedure. This paper explores the nuances, limitations and practical aspects of Follicular Unit Extraction.


Follicular Unit Extraction was performed using 1mm punches to separate follicular units from the surrounding tissue down to the level of the mid dermis. This was followed by extraction of the follicular units with forceps. The FOX test was developed to determine which patients would be good candidates for the procedure. The test was performed on 200 patients. Representative patients who were FOX positive and FOX negative were studied histologically.


The FOX Test can determine which patients are suitable candidates for Follicular Unit Extraction. Approximately 25% of the patients biopsied were ideal candidates for FUE and 35% of the patients biopsied were good candidates for extraction.


Follicular Unit Extraction is a minimally invasive approach to hair transplantation that obviates the need for a linear donor incision. This technique can serve as an important alternative to traditional hair transplantation in certain patients.

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