Much of the talk when someone is enquiring about a hair transplant revolves around the topic of density, how many FU per cm2 will be placed in the hair line and behind, will it be natural, and will it be thick. Of course this is a relevant question but possibly too much emphasis is placed on this and other factors that make up the result are forgotten about; such as hair characteristics and one rarely discussed; the number of hairs per follicular unit. There is always a mean number and some say there are more hairs per FU with FUE or Strip/FUT but the fact remains if an intact is removed it will average whatever the person has, and generally it works to approx. 2.2/3 hairs per FU. This is not necessarily the natural average but normally the extracted average, hence being able to easily calculate it. And this can vary dependent on the procedure and the placement, hair line requiring more single hairs so the number drops whereas if the placement was behind a hair line with mainly multiple hairs the number increases.
FUE and FUT/Strip both rely on the number of grafts placed to give a result, but more importantly is the number of hairs per follicular unit because this can make a large difference in the result; this is the distribution of hair. The placement of the FU in a skilled and artistic manner will get the most thickness and coverage to assimilate a head of hair.
Depending how the FU are extracted with FUE will determine whether a “true” FU is removed and this will be a large factor in the result. For example if an FU is removed intact be it one hair or a multiple FU up to 4 hairs then the hairs per graft will reflect this in the % split. A number of factors can attribute to the number of hairs per graft, for example incorrect extraction could lead to removing more than one FU or transecting an FU; this can either mean larger grafts or if transacted could mean more grafts are created accidentally but the hair count is greatly reduced per graft.
This is important to understand as the distribution of FU decides the result; as most realise, a hair line will typically take 600-800 SINGLE hair FU and if there is temple point rebuild this can be over 1000. Behind the hair line a gradual increase needs to be created from 2 to 3 to 4 hair FU. BUT if a greater number of single hairs are placed then this will impair the distribution, so a larger number with lower “thickness” in a smaller area. You may be able to place a density of single hairs at 90 FUcm2 behind a hair line, but the actual THICKNESS will be less than three hair FU placed with a low density of 35 FUcm2; almost a third density placed but more hairs and more importantly more thickness.
DISTIBUTION of intact FU= results, the number of grafts is relative to the number of hairs, if there is not a balanced distribution of hairs the appropriate placement will not equal the thickness required and coverage to achieve what probably everyone would aspires to in a hair transplant.
Here is a working example:
Take a case of approximately 2500 grafts or follicular units with a hair count and split of
Follicular Unit Numbers: 1 hair 704; 2 hair 765; 3 hair 689 & 4 hair 358
A total of just over 6000 hairs, all in their natural groupings allowing for the educated distribution to gain a solid result. Then take a 4000 case with an almost even split of single and two hair follicular units with a few three’s; reaching approx. 6700 actual hairs. 1500 more grafts but only 700 more hairs.
Naturally some people have smaller hair numbers (groupings) per FU and in some cases this may render them not suitable for a hair transplant; or possibly transection when punching may cause the FU to be split into a smaller hair group, either way it must be recognised that graft numbers are only relative to the hair count and the distribution of the FU when being placed. Either way, be it natural small groups or transacted it can lead to a sub standard result and so when calculating density for example in the donor area the hair count should also be considered as a major factor.