Scalp hair grows in groups of hairs, typically these groups range from a single hair to a group of 5 hairs; these groups of hairs are known as follicular units (FU´s) and spawned the name of the two main hair transplant procedures. Follicular Unit Transplant “FUT” also known as Strip Technique and Follicular Unit Extraction, or “FUE” being the two recognised hair transplant techniques.
Dependent on the area of the scalp around the sides and back the FU´s differ in size; the sides more single and two hair units are found and the back more three and four hair units are found. The number of hairs is a vital factor when considering a hair transplant and having a blend of single and multiple follicular units. Once the FU´s are removed from the donor area they also become known as “grafts”.
It is important to ask what the definition of a graft is, is it a natural follicular unit or just a group of hairs. Having a variety of sizes is vital to attain a natural looking coverage and density, as it is impossible to replace like for like hair the multiple hair units allow for a higher distribution over the scalp.
Single hairs are important when placing along a hair line, the create a natural, soft look to the hair line with the number of hairs increasing per cm² behind the first few mm´s to increase density. If naturally the average number of hairs per FU is low then it can mean you make a poor hair transplant candidate, especially if the level of hair loss is high or potentially will be high in the future. The average number of hairs in a FU is approximately 2.20 hairs. When a hair transplant is performed the Doctor will separate the FU into their natural groups and can give you the number 1, 2, 3 and 4 hair units and from this you can determine the number of hairs.
1 Hair: 729 (729)
2 Hair: 758 (1.516)
3 Hair: 1.913 (5.739)
4 Hair: 877 (3.508)
Total: 4277 (11,492) 2.68 hairs per FU