Practical Hair Density possible in Hair Transplantation

On an average, an adult human scalp contains 100,000 follicular units in total.  In baldness, there is already 50% loss of follicular units in the bald looking area. On an average the density of a non bald scalp is 80-100 follicular units per square cm. This density varies from person to person.

Hair transplantation can hide the baldness in single sitting, but it cannot provide the natural density in one session. In hair transplantation, doctors can plant 25-35 follicular units (FU) per square cm, which is much less than the normal density, though this much density can hide the baldness with artistic planning of the grafting. For normal density, a second sitting of 25-35 follicular units (FU) per square cm is required. Sometimes, a third sitting may be required for natural density.

In the front hairline, usually single FUs are grafted for natural look. In this area, 35-45 FUs can be planted in 1 square cm. In the crown and vertex area, the double and triple FUs are planted.

With over enthusiasm if more than 40-50 FUs are planted in 1 square cm then the chances of growth will be less because there will be competition between the grafts for blood supply.  This competition among FUs will result in death of a lot of hair follicles as well as necrosis of skin. That means permanent loss of follicle and permanent scar on head. This can be better understood with an example: In plantation in our garden, we are always advised to keep a minimum distance in between the plants for optimum growth; else most of the plants die.

For doctors, dense packing is an ongoing learning process; the goal is to achieve density while staying within the scalp’s safe limit of vascular damage.