The Donor Site

• Definition of the Donor Site
• Donor Site Evaluation
• Effective Use of the Donor Site
• Donor Site Harvesting Techniques

When hair-bearing tissue is withdrawn from one area of the scalp for transplantation to an area that is hairless due to male-pattern hair loss (MPHL), the withdrawal is made from the donor site-an area unaffected by the genetics of MPHL. The donor site in the balding male is hair-bearing scalp tissue that runs from an inch or two above the ears and temples to the back of the head. This donor area might be called the savings-and-loan area: hair follicles in this area are saved from the effects of MPHL and are available for loan by transplantation to scalp areas that have lost hair due to MPHL. Transplanted hair follicles from the donor site retain their resistance to MPHL genes and continue to produce hair at the recipient site.

In planning a hair transplantation procedure, the physician hair restoration specialist will pay as much attention to the donor site as to the recipient site. Accurate assessment and effective use of hair-bearing tissue at the donor site are important factors in the eventual success of hair transplantation in any individual patient.

The potential “Permanent” donor zone as determined by an examination of hair density in the donor area in 328 randomly chosen men aged 65 years or older. Note that it is 69mm high in the midline of the occipital area and that hair with fewer than 8 hairs per 4mm circle is present superior, inferior, and anterior to the shaded “safe” donor area. (From unger W, ed, hair Transplantation, 3rd ed, New York: Marcel Dekker, 1995.)

Although the donor area exists in all male patients, it is not precisely the same and can vary considerably from patient to patient. The physician hair restoration specialist will want to identify the “safe” hair-bearing donor tissue that will permanently retain its resistance to MPHL genetic control. Making this identification requires careful evaluation by the means of the patient’s family history of hair loss and by scalp examination. Hair-bearing tissue that, at casual examination, may seem to be within the general area of a prospective donor site may eventually be lost to MPHL over succeeding months to years. Careful evaluation significantly reduces the possibility that the hair-bearing tissue chosen may eventually be lost to MPHL.

Careful evaluation of Donor area includes:

1. Family hair-loss history:
   A detailed look at a patient’s family history of hair loss can suggest a probable pattern of the patient’s future hair loss. A family pattern of severe hair loss may indicate that the “safe” area of a donor site is limited in size-that is, it is probable that the amount of hair-bearing tissue that will remain resistant to MPHL is limited, and this will limit the amount of donor tissue that is available for transplantation.
2. Scalp examination:
   In MPHL, careful scalp examination indicates to an experienced physician hair restoration specialist where future hair loss may occur within the prospective donor site.

   Evaluation of the prospective donor area by family hair-loss history and scalp examination provides information vital for planning the hair transplantation procedure. However, assessing the amount of hair-bearing tissue to be used for transplantation is considered in context with other important factors:

3. The age of the patient:
   Planning the use of donor hair may require different strategies for younger versus older men. Younger men with progressive MPHL may need several transplantation procedures over a number of years to keep pace with hair loss, while older men may need fewer. If the donor area is equated with a savings-and-loan, the strategy for younger men is to keep more donor hair in reserve for future use.
4. The type of hair loss:
   While MPHL is progressive for the lifetime of a man, not all MPHL progresses to its most severe form. (Click on Hair Loss-Why? and Norwood-Hamilton Scale for illustrations of types of hair loss). Treatment of a “high forehead” (Norwood-Hamilton Type I) type of hair loss may be all that is needed by some patients; for example, in an older man, “high forehead” hair loss is unlikely to progress to a almost total (Norwood-Hamilton Type VII) type of hair loss in the patient’s lifetime. In a younger man, “high forehead” hair loss may progress to a more severe form, but if family history and scalp examination suggests otherwise then planning for transplantation should be based upon the information derived from history and examination plus the wishes of the patient as discussed with the physician hair restoration specialist.

When MPHL hair loss is substantial and donor area is limited, hair restoration planning may also include a surgical procedure such as scalp reduction (Click on Surgical Treatments for information about scalp reduction) that will reduce the area of scalp that requires transplantation. The pros and cons of this procedure should be discussed with the physician hair restoration specialist. Assessment of the donor area for hair-bearing tissue to use in transplantation also includes assessment of hair characteristics:

1. Hair density:
   Hair occurs with different densities in different locations within the donor area. Hair density is defined as the number of hairs per square inch of scalp; density varies at different locations on the scalp. Harvesting of donor tissue for transplantation takes hair density in to account-for example, transplant grafts consisting of multiple hair follicles are best taken from areas of denser hair growth within the donor site.
2. Hair caliber:
   The caliber (cross-section) of individual donor hairs has implications for an appearance of “fullness” or “sparseness” of transplanted recipient areas. Hairs of heavier and finer caliber are frequently interspersed to create a more natural appearance in the recipient area.
3. Hair color:
   PThe most natural appearance in recipient areas is achieved by appropriate balance between the color of donor hair and the color of scalp skin in the recipient area.
4. Hair texture:
   Hair texture ranges from fine “stringiness” to “frizzy” fullness. Each texture has characteristics useful in achieving maximum naturalness of appearance in the individual patient. The effective use of hair texture is heavily dependent on the wishes of the patient as discussed with the physician hair restoration specialist.
5. Hair curl:
   As with hair texture, hair curl is a characteristic that can be used effectively to achieve the “look” the patient wishes to achieve. Markedly curled hair-as in men of African ancestry-usually grows from curved follicles.

   Walter Unger, MD, one of the “fathers” of modern hair transplantation, has observed that no donor hair characteristic is better than any other for achieving the optimum outcome for the individual patient. The best outcome is the one that achieves the wishes of the patient and the professional satisfaction of the physician hair restoration specialist.

Techniques for harvesting donor tissue have improved steadily over the years. Newer techniques may improve hair yield as much as 50% to 100% over older techniques. Newer techniques generally result in less donor-site scarring as compared to older techniques. The patient should ask for a description and explanation of donor-site harvesting as part of full preoperative discussion with the physician hair restoration specialist. Understanding of how the donor site is to be used is as important to the patient as understanding how donor tissue is to be used in the recipient site.