Limitations of Donor Hair That Can Be Used in Hair Transplants

Transplants

Donor supply is critical in performing hair restoration procedures and repairing bad hair transplants. It is true that many of the cosmetic defects created by poor techniques can be partially or completely reversed by meticulously removing and re-implanting unsightly grafts. However, the main factor that generally prevents the surgeon from achieving all of the patient’s restoration goals is a limited donor supply. A depleted donor supply can be the result of wasted hair during a bad hair transplant procedure, or due to the patient’s own genetic limitations.

Hair wastage due to poor surgical techniques, as discussed above, is usually the main cause of donor supply depletion. The early telltale signs of hair wastage may be a transplant that appears too thin for the number of grafts used, poor growth manifested as gaps at the hairline, or uneven density in areas where the coverage should be uniform. The fact that donor hair was wasted might be surmised from a donor incision that was longer than expected for a given number of grafts, or an abnormally low density in the donor area near the donor scar. Unfortunately, it is very difficult to ascertain the exact underlying causes after the fact and, by the time surgeon is aware that he has run out of usable donor hair, the damage to the patient has been done Hair Transplant Miami.

Because an adequate donor supply is so critical to a successful repair, accurately assessing the amount of hair available becomes paramount. When performing a hair transplant procedure on a virgin scalp, quantifying the donor supply is rather straightforward, as density and scalp laxity are relatively uniform in the donor area. In repairs, however, additional factors come into play. Even though there may appear to be enough hair in the donor area, it may not be surgically accessible. Factors that limit the available donor hair include:

> Low donor density
> Fine hair caliber
> Poor scalp mobility
> Scarring

Low Donor Density –
Donor hair density (donor density) can be measured using a simple hand-held device called a Densitometer. This instrument is invaluable for the assessment of donor density, follicular unit composition, and miniaturization. Patients with high hair density have more hairs per follicular unit, rather than having follicular units spaced more closely together. The converse is also true. A person with naturally low hair density would have fewer hairs per follicular unit, but with the same spacing between the units (i.e., 1 follicular unit/mm2). At very low densities, this rule is less applicable.

The scarring produced by the traditional punch-graft method, that used the open-donor technique to harvest the hair, is a visible marker of the amount of surgery performed. One can easily estimate the amount of donor hair used by comparing the area of open-donor scarring to the remaining virgin donor scalp. In strip-harvesting, however, the linear scar gives little indication of the strip’s original size, since it only reflects the length of the excised skin and not the width. With this method, the actual amount of tissue removed cannot be easily ascertained.

The percent decrease in follicular unit density will provide an indication of how much tissue was removed and more important, how much remains to harvest. In general, a person’s follicular unit density can be decreased to approximately 0.5 units/cm2, before the donor area will become too thin and no more hair should be harvested. Therefore, if the follicular unit density in the area of previous donor harvests measures 0.75/mm2, approximately half of the potential donor hair has been used and approximately half of the usable hair remains. In the example given above, a 12.5% decrease in follicular unit density means that 25% of the available donor hair in that area was used in the prior procedure.

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