TLDR Only about 14% of hair follicles can be safely removed in hair transplants without affecting the surrounding area.
The 2016 research article by Paul T. Rose, MD, JD, FISHRS, discussed the effects of Follicular Unit Extraction (FUE) on the donor area in hair transplantation. The author challenged the common belief that 40-50% of the donor area follicular units (FUs) can be removed without significantly affecting hair density. Instead, he suggested that only about 14% of FUs can be harvested without affecting adjacent FUs, based on densitometry images. This would equate to 1,800-2,200 grafts for a person with an average FU density of 80 FUs/cm2. The author warned that harvesting adjacent FUs could result in visible areas of hairless skin of 6mm2 or more, contradicting the perceived benefit of FUE allowing patients to wear their hair short without evidence of surgery. He also noted that patients with finer hair, low hair density, and fewer 3- and 4-hair FUs are at higher risk of appearing to have thinning hair. The author recommended discussing the potential for thinning and scar creation with patients before performing FUE.
153 citations,
August 2002 in “Dermatologic Surgery” Follicular Unit Extraction (FUE) is a less invasive hair transplant method with minimal scarring, suitable for about 60% of patients, especially those needing fewer grafts and quicker recovery.
9 citations,
March 2020 in “Dermatologic Surgery” Both Follicular Unit Transplantation (FUT) and Follicular Unit Excision (FUE) are effective hair transplant methods; the best choice depends on the patient's needs and the surgeon's preference.
15 citations,
September 2016 in “Hair transplant forum international” The "open punch" technique for hair transplantation can help reduce damage to hair grafts and may be especially useful for beginners and in cases with curly hair.
9 citations,
January 2018 in “Hair transplant forum international” Researchers concluded that safe hair follicle extraction limits in FUE vary by individual characteristics and proposed a method to calculate these limits to maintain appearance.
13 citations,
March 2013 in “Dermatologic Surgery” The document concludes that hair restoration has advanced significantly, with FUE becoming more popular, and stresses the importance of physician training and ethical practices in the field.
April 2018 in “Dermatologic Surgery” A new surgical technique using vellus hair grafts effectively treated vitiligo without causing unwanted hair growth.
5 citations,
January 2019 in “International Journal of Dermatology” Hair transplantation effectively lowers high foreheads in Asian women, with high satisfaction and no major complications.