The size of punches is an important subject in follicular unit extraction and follicular isolation techniques. It is also a strong marketing tool for some groups who attempt to mislead patients into believing that they can always use a small punch and they always get a high yield with little destruction to the follicles and follicular units. We are perhaps the most experienced in follicular unit extraction at this time with more than 300,000 grafts removed by our patented follicular isolation technique of extraction. We rely on this vast amount of experience to help guide us in the art of follicular unit extraction.
Patients generally believe that a smaller punch results in a smaller scar. We believe this is not always the case. It definitely has not been studied. The general rule in skin surgery is that an incision smaller than 1.5 mm in size will heal without a visible scar to the naked eye. Therefore, in theory there should be no cosmetic advantage to a smaller incision than 1.25 mm in diameter or 1 mm in diameter and there could be disastrous results from smaller incisions in regard to hair shaft damage. Furthermore, the total number of hairs transferred by using smaller punches can be significantly less.
One must remember that individuals who have hair loss want hair on the areas where they do not have hair. The advantage of FUE is that it allows us to leave an imperceptible scar in addition to adding hair to the areas of loss. Adding hair can be efficient or inefficient. In other words, for every 100 hairs you attempt to move, you may move 92 to 97 intact hairs or you may move only 62 intact hairs. The ones you do not move are damaged in the removal process. If the damage ratio exceeds 8%, the process becomes very inefficient. You will not get as much hair from every graft as you desire. Your resulting coverage will be less. Furthermore, you will pay more for less hair. In general punches smaller than 1.0 mm are good for two hair or one hair grafts. If you attempt to move larger grafts than two hairs, your injury rate will increase and your efficiency will decrease significantly.
In our office we average 2.49 hairs per follicular unit in our method called follicular isolation. This is about 25% more hair per graft than you can expect from a the total use of a smaller punch. Furthermore, we are able to keep the transection rate at 8% or less. Often it is 3%, which is better than with most strip surgeries. We vary the punch size based on the size of the hair shafts and the number of hair per follicular unit (technically referred to as the calculated density).
The hairs exit from the scalp in natural clusters. They are very close to one another on the surface. On the surface the clusters of hairs are bound closely into one or sometimes more than one follicular canal. As they enter the skin, they begin to spread out. In hair surgery we call this hair splay. A useful analogy is a bundle of flowers that are in a vase. At the top of the vase, they are very close to one another. As the flowers enter the vase, they progressively deviate from one another. Some vases are narrower at the neck and some are wider. The wider ones will not gather the flowers as closely to one another at the neck. Some vases are wider at the base. In the wider ones the hairs will be farther apart; there will be more splay or distance between the individual flower stems. In more narrow bases the flowers will be much closer to one another. There will be less splay or distance between the individual stems. The same thing happens with the scalp’s donor area. In some individuals there will be a wide variety of narrow bundles. In other individuals there will be a preponderance of follicular units exhibiting splay. In other individuals there will be a variety of bundles. Some have more splay than others and some have very little splay.
Another concept to understand is the size of the hair follicles and their surrounding dermal sheath. The average scalp follicle is 0.42 mm wide from dermal sheath to dermal sheath. A two hair follicular unit averages 0.82 mm wide. This means you can use a 0.5 mm punch all you want, but the two hair follicular unit will not fit into it. In other words, you will need a little luck in your extraction process, a perfect incision, and no margin for error. You will have a lower yield and an inefficient procedure. A 0.75 mm punch will work, but the incision must be perfect. Humans are not always perfect. A 0.8 mm punch will work on the 2 hair follicular unit also, but the human must also be perfect. The 0.9 mm punch provides a larger cushion and we have used it quite often for 2 hair grafts, but it is not possible to use it on every patient or every 2 hair graft. The 1 mm punch provides a larger cushion for human error and a very high yield with most grafts and in most individuals.
As the size of the follicular unit increases, the width also increases. This can present an increasing problem for the hair restoration surgeon. In our office the average follicular unit has 2.49 hairs. Therefore, we must tailor the punch to the patient and to the follicular unit. In other words, if you want a more efficient procedure, the procedure must be customized to the patient and the follicular units. Otherwise, you will have a far lower efficiency ratio and a lower yield. You will pay more for less hair and you will unnecessarily put donor hairs at risk. The ideal donor result is important, but the yield should be a chief consideration to the hair restoration surgeon and the patient.
To date we have not noted an increase in scar formation from the use of larger punches. Larger punches have not shown more collateral damage or shock loss to surrounding hairs in the surrounding follicular units. This has not been studied yet, however. The main problem from follicular unit extraction remains the removal of a follicular unit from the natural follicular geometry of the donor area. This problem is the same regardless of punch size.