The Donor Area

The objective in all patients is obviously to use only donor hair that would have been permanent in its original site. What is less obvious is how one can be certain of this likelihood. Alt, in the second edition of this textbook, suggested that a line drawn perpendicularly from the external auditory canal should define the anterior border of this "safe" area. .¹ The superior border was a more complicated affair, however. In most patients, his safe donor area began on the anterior border where it was 6.5 - 7.0 cm wide and steadily narrowed as one moved posteriorly. In the midline of the occipital area, he stated that the ultimate donor area is substantially narrower than it is superior to the external ear. (This is contrary to Unger’s study that will be discussed later.) Alt suggested that a horizontal line be drawn from a point 2 cm superior to the reflection of the skin of the external ear and the scalp. The point at which this horizontal line intersects the midline of the occiput was to be the superior border of the safe donor area at that location (Fig.1a). He noted that, obviously, in some individuals, the donor area might be wider or narrower at various points, but believed the foregoing perimeters would be valid for most individuals. In addition, he counseled – and we agree – that at least 2.5 cm of unharvested permanent hair be left superior to the most superior donor areas to provide adequate long-term camouflage of scar lines.

When deciding on the inferior border in the donor area, it is wise to remember that male pattern baldness (MPB) also affects the inferior aspects of the rim hair; therefore, one should leave an unharvested margin of safety at this level, as well as superiorly. Thinning inferiorly occurs later and less markedly than thinning elsewhere, but it is generally accepted that it usually does not occur to a cosmetically significant degree inferior to a line drawn horizontally from the inferior reflection of the skin of the external ear and the scalp to the midline of the occipital area. The inferior border, of course, should be decided upon after taking into account the patient’s age, family history, and findings on physical examination (see below), but if one accepts Alt’s superior border for the "safe" donor area, one would in many cases be left with only a 20 mm width of usable donor tissue as the ultimate in safety.

There are no substitutes for taking a careful history of the extent of baldness in family members and for carefully examining a prospective patient’s scalp for evidence of areas of future thinning. Wetting the hair is especially useful in delineating areas that, in the future, may be affected by MPB. The younger the patient is, the wiser it would be to keep within the borders suggested by Alt. As we shall see below, however, such a course may represent ultimate safety but is overcautious to a substantial degree in a large majority of patients. In particular, for at least the last 33 years, Unger has often gone further anteriorly in the temporal area than Alt’s safe anterior margin.¹ Age is an important factor in deciding how much of the temporal area (or other areas) can be used. The older the patient, the more confident one can be. However, Unger and others are grateful that many other surgeons appear to have agreed with Alt’s advice. The temporal areas are often a largely untouched reserve of donor tissue in patients seen for repair of transplanting done by others.

In 1994, Unger et al reported on a study on 328 men aged 65 years or older. ¹ The patients were subdivided into the following age groups: 65-69 years, 70-74 years, 75-79 years, and older than 80 years. The degree of alopecia (class I – VII Hamilton/Norwood) was noted for each. "Acceptable" donor sites in these individuals included only areas containing eight hairs or more per 4 mm diameter circle. The widest inferior-to-superior measurements of zones containing this hair density were recorded in temporal and parietal areas, as well as in the midline of the occipital area. In individuals with type I and II alopecia, the height of the donor area was arbitrarily limited to that of the individual with the greatest height in type III MPB. In addition, the distance anterior or posterior to Alt’s safe anterior border, where acceptable density was found, was noted and is recorded under the title "anterior". (Table 1).

One can view the findings from two vantage points: (a) all men in the sample and (b) the majority of men in the sample that a transplant surgeon would most likely treat. The latter group might reasonably exclude those with types I and II MPB (although there are occasional exceptions), and to produce results that would be meaningful for most patients might exclude all type VII also. Why? If one analyzes Table 1 and excludes patients with types I and II from the sample, one would find that (a) in the age group 70-74, 57 of the remaining 69 patients (82.6%) have types III-VI MPB and (b) in the age group 75-79, 52 of the remaining 62 patients (83.9%) have types III-VI MPB.

It is worthwhile noting: (a) the average life span of a man in most parts of the world is less than 80 years of age; (b) more than 80% of the men between 70 and 79 who would likely be treated by transplant surgeons have types III-VI MPB (the percentage drops to 70.5% in the group 80 years or older but still represents a substantial majority); and (c) if one were to include patients with types I and II MPB, the percentage of patients with less than type VII MPB would be even higher. These figures should provide some comfort to many of us who have feared that a majority of our patients would progress to type VII MPB before they died. While there is no way of accurately predicting everyone who will fall into the latter group – no matter how small it is – it therefore appears it would be inaccurate to make this assumption for over 80% of our patients. If all of them were treated as if they were going to evolve into a type VII MPB, this would be patently unfair to them. There is no doubt that MPB is progressive for the lifetime of any patient. What should be reassuring is that only a smaller than expected minority live to the point where they reach class VII MPB.

Table 2 outlines the findings from the vantage point of all 328 subjects in the study: 55 aged 65-69 years; 81 aged 70-74 years; 73 aged 75-79 years, and 119 aged 80 years or more. Table 3 outlines the findings from the vantage point of those approximately 80% of patients with types III-VI MPB. There were a total of 216 patients in these categories: 33 aged 65-69 years, 57 aged 70-74 years, 52 aged 75-79 years, and 74 aged 80 years or more.

There are many ways one could use the figures shown in the tables to delineate a "safe" donor area. For example, one could take the lowest numbers for each parameter regardless of the age group in which it occurred. This, of course, would be the safest "safe" donor area but would also almost certainly be far more restrictive than a large majority of patients would require. One could also average the findings in patients 65-79 years of age (Table 3). This would also be an extremely safe donor area for over 80% of patients (under the age of 80). Such an area would consist of more or less a parallelogram in the parietal-occipital area whose inferior border would be chosen by the surgeon on the basis of, for example, 10 or more hairs per

4 mm diameter circle, the patient’s age, and the family history. The number "10" would provide a "cushion", allowing for a subsequent decrease in density with aging to eight hairs to 4 mm diameter circle. The number of hairs per 4 mm diameter circle could be increased if one wanted to approach the donor area in an even more conservative fashion. The superior border of the parallelogram would similarly contain at least 10 hairs per 4 mm diameter circle and would angle somewhat inferiorly, parallel to the post-auricular superior hair margin, as one moved from its anterior to mid-occipital borders. As I will show later in this chapter, this area alone is more than sufficient to provide for as many as six sessions. A narrower more or less parallelogram would sit on the inferior one, with its posterior border beginning in the mid-parietal area. Its anterior border could be 28.6 mm anterior to a line drawn vertically from the tragus and would be parallel to the anterior temporal hairline unless there were good reasons to suspect the area anterior to the tragus would not remain sufficiently dense over the long term. This superior parallelogram would be 10 mm high – again subject to clinical findings and family history. Its superior border would drop somewhat inferiorly as it progressed posteriorly to meet the midline point of the safe occipital donor area (Fig.1b). Lastly, in the mid-temporal area, the "safe" donor area could extend 55 mm superior to the superior parallelogram and then descend to meet the safe donor area in the mid-parietal area. A third way of using Table 3 would be to use the figures for patients 75-79 years of age and the dimensions shown in Fig.1b. This is, in fact, the "safe" donor area the authors prefer, as it seems to be a good compromise between caution and over caution. Each reader, however, is free to choose one’s own balance and one’s own "safe" donor area.

It is important to point out that this design incorporates permanent hair whose long-term density would be eight or more hairs per 4 mm diameter circle, but that according to this study, less dense permanent hair would persist superior and inferior to these boundaries in virtually all patients. Some of this less dense hair, in some patients, could be used as additional donor material if it were necessary. While eight hairs per 4 mm diameter circle might be a wise minimum if standard grafts were being harvested, transplanting with standard grafts has essentially ceased to exist. A minimum requirement of eight hairs per 4 mm diameter circle is probably too high a minimum density if one is using strip harvesting for follicular unit transplanting (FUT) and micro-minigrafting. In such cases, one is usually looking for grafts containing only one to six hairs, and the physician can simply increase the width of the strips to produce the desired number of FU or minigrafts. Thus, the acceptable donor area for strip harvesting for FUT and micro-minigrafting is almost always larger than that suggested by the above figures.

Unger believes that if one combines a) Alopecia Reductions (AR) or scalp extensions, b) total excision techniques in donor area harvesting as described in this chapter, and c) FUT or micro-minigrafting (to produce less dense coverage that still looks natural), with appropriate planning one can now reasonably expect to satisfactorily treat the entire area of MPB in a majority of patients. This is a remarkable advance from 10 years ago! His position is intentionally provocative and no doubt will lead to much debate. Key requirements are reasonable patient density objectives, a well-experienced surgeon, and a staged treatment of the recipient area using no more donor tissue than is absolutely necessary in any region.

It is important to emphasize, again, that a family history and clinical examination are necessary to confirm that the boundaries of the proposed "safe" donor area would be likely to apply to the individual being treated. One should always err on the side of caution. For example, 14 of Unger et al’s study patients did not have acceptable donor area density anterior to the tragus. In a very few cases, narrower parallelograms would be more appropriate or no acceptable donor area might be present. On the other hand, in many more patients, wider parallelograms would be warranted. The above-noted boundaries are not suggested as perfectly safe for all patients but represent the implications of the only objective scientific evaluation of this area ever done. Based on that investigation, they would be very safe in approximately 80% of patients under the age of 80 years. More restrictive areas can be chosen, for example, if one prefers to plan for patients who might live to 80 or more years or if the patient has a father or maternal grandfather with type VII MPB. Obviously, it bears repeating that the older the patient, the more certain one can be of the "safe" donor area.