Using the donor area wisely in hair transplantation: mathematics matters

Some men "destined" to develop with Hamilton Norwood class VI balding may only have 4000-5000 grafts available to move in their entire lifetime

Using the donor area wisely in hair transplantation

How valuable is a follicular unit nowadays?  What is the real cost of a transplant? 5 dollars per graft? 7 dollars per graft? 10 ? 3? Well, follicular units are still priceless because once they are gone the body can't regenerate them. 

Someday, scientific advances might allow us to have an infinite supply of donor hair. For now, however, it's finite. Because donor hair is finite we always need to keep in mind one important principle: to use it wisely.

One of my favourite hair transplant papers from 2013 was a study by Dr. Walter Unger and colleagues. They  published a nice study looking at how many grafts the 'average' person has in their donor area. For someone destined to be Hamilton Norwood scale V or VI it ranges from 4200 to 7900 grafts. These numbers are important to keep in mind for reasons I'll describe.

EXAMPLE 1:

Consider a 33 year old man with frontal hair loss. When he meets in the office, it's clear that he is at high risk for further hair loss. He does not want to consider any hair loss medications to stop or prevent hair loss out of fear of side effects. In the worse case scenario he's destined to be a Hamilton Norwood VI with low density donor when he's 55.  To bring his hair back to the original density he once had at 18 he would need 3000 grafts packed at high density (where the survival of the grafts is possibly 70%). However, to significantly improve his density, make him look and feel great about his hair, he needs 2400 grafts (where the survival of grafts is likely 95 %). 

Which of the following do we do?

SITUATION 1

Use 3000 x 70% survival  = 2100 growing grafts in final result; 900 wasted;

Total grafts 'left' in the donor bank for future transplants = 1000 grafts

SITUATION 2

Use 2400 x 95 % survival = 2280  growing grafts in final result;  120 wasted

Total grafts left in the donor area bank for future transplants = 1600 grafts

ANSWER:

Clearly, there is a slight preference for Situation 2. The reality is that with 2100 growing grafts or 2280 growing grafts that patient will have an improved look.  With situation 1 (and unrealistic expectations), the patient may feel that he didn't quite get the density he was hoping for but will still have a nice improvement. However, on account of the potentially poorer growth of densely packed grafts, he'll have unnecessarily used up or wasted many hundreds of grafts.  This won't make any difference to the patient unless he wants to have a second transplant down the road (see example 2).

EXAMPLE 2: 

The same man as in the above example returns to the office in the year 2030. He has hair loss in the crown and would like another transplant. You estimate he needs 2000 grafts for full dense coverage but 1500 grafts to give him a nice coverage so that the scalp can't be seen.

Which option (Situation 1 or Situation 2) was the best option for the original first transplant session at age 33 ?

ANSWER:

It comes as a surprise to many that the best option is situation 2. By using up fewer grafts, we actually have a better outcome for transplant session 1 at age 33 (because of the higher survival rate of grafts) and now in year 2030 we have more grafts available to take. Our patient not only looks better in his mid 30s with careful planning but he looks better in his mid 50s

Comment

In hair transplant surgery, mathematics matters. The density of the recipient area that we plan out matters. The predicted density and amount of donor area in the future matters. The type of hair, quality, calibre and curl matters. The decision on FUE vs strip matters. Careful planning can help a large proportion of patients maintain good scalp coverage throughout their life. The price of a follicular unit is priceless as they are limited and can't be replaced.