The “Safe Donor Area” in Modern Hair Restoration

The guiding surgical principle and basic tenet of surgical hair restoration for decades has been the concept of “donor dominance,” which gave birth to the oft-quoted phrase: “borrowed hair never loses its passport.” For years this concept further led to the recognition and creation of the permanent donor area or safe donor area (SDA), a horseshoe-shaped band of hair-bearing scalp that runs around the back and sides of the head. The follicles in this SDA were believed to be genetically “programmed” to be immune from the attack of androgenetic alopecia (pattern hair loss) and thus, if moved to the balding scalp, this area will forever remain “safe” and provide a lifetime of natural looking, DHT-resistant hair. The SDA was (and still is for many) the North Star of the surgeon’s universe, the lodestar that guided every strip harvest, every follicular unit extraction (FUE). It has, however, become clear that in today’s practice this long-held sacred cow of hair restoration is being re-evaluated in a major and necessary way. Emerging from an unholy alliance of relentless patient demand for higher and higher hairlines, crown fills and density; younger and more aggressive hair loss patterns, along with a better appreciation for and evaluation of long-term surgical outcomes, the traditional donor zone’s size, and above all, its long-term stability are now being hotly debated in the lexicon of hair restoration philosophy and are rapidly changing it.

Defined in its most traditional form, the SDA is an area on the back and sides of the scalp that is usually 6-7 cm in height that extends from a point superior to the ear on one side (say 2-3 cm above the superior tragus) across the occipital protuberance in the back of the head to the same point on the other side. The reason it is called the SDA is based on the relative observation that even in advanced Norwood Class VI and VII patterns this area almost never exhibits androgenetic alopecia and remains full and DHT-resistant. The thinking of the early punch graft and the early plug transplant techniques was firmly within this belief. The more grafts taken from this safe zone and placed in the balding front and top the better. This simple paradigm still makes sense and is mostly safe for the patient with a mild to moderate loss and with stable, very robust donor characteristics. It is an easy concept to follow and when used as designed, should provide predictable results with very little risk of long-term “donor shortage.”

The reason why this dogma is now being vigorously re-examined is a multitude of related issues. First and foremost, the hair restoration patient in the 21st Century has changed and continues to change at an alarming rate. The patient in today’s society is often a lot younger, better informed and in general, has much higher expectations. He or she is armed with information gleaned from the internet message boards and social media and rather than walking into the office seeking help for a moderate hair loss, this patient wants to defy his or her genetics. Armed with the concept of donor dominance and its corollary, the safe donor area, the patient wants a full, dense head of hair that would put most 20-year-olds to shame. This maximalist trend, which goes hand in hand with almost all the other shifts in hair loss surgery we are seeing in modern times, has led the patient to demand a higher and higher density of follicles not only on the front but in a more pervasive fashion on the top and crown and in some cases to even completely rebuild the hairline to achieve “permanently” high density over the whole scalp. This need for ever-increasing follicular real estate has put an enormous strain on the donor supply that never existed to the same extent in the past. In order to provide the patient with as many grafts as he or she wants, surgeons are harvesting more and more grafts from these donor areas than ever before in an effort to reach what may seem like an unlimited volume of follicles. This they are doing both to and at the edge of the safe donor area and from a very high-risk patient population and in an effort to try and meet those ever-higher demands, the assumption that everything that is harvested is stable and long-term permanent is being severely tested.

The best and most problematic challenge to the classic SDA comes from the strategic management of younger patients with aggressive pattern loss. The classic case is a 22-year-old patient who comes in with a Norwood Class III pattern with a very early bald vertex and a family history of a father and brother with severe Class VII balding. He is one of the most vexing types of patient because his donor area may look like a lush, mature beaver coat and be quite dense at the time of consultation but to do a transplant at this stage without any long-term plan is setting himself up for future disaster. For these young patients the safe zone at any given point in time is mostly just a theoretical concept and not something that is actually an absolute and guaranteed reality for a young man. The SDA in this case will change over time, over the course of the next 20 to 30 years. So, the 22-year-old at the age of 50 may well look like his dad or his brother and have a markedly higher SAD than the one that is being measured and used as the basis for a surgical plan right now. This process, when it occurs, has been termed “donor area miniaturization” or “donor area thinning.” While the deep and inner portions of the occipital scalp may never be at risk and may indeed remain dense for a lifetime, the superior and lateral border can and often does progressively thin out. The result of a surgeon who over-harvests from these marginal areas in a young patient is what we now know as the over-harvested “depleted” donor area, which becomes all too obvious once the patient ages and his/her own native hair in those marginal SDA zones continues to thin or disappear altogether.

This risk is further compounded by the wide-spread popularity of FUE. While there are many pluses to FVE in terms of better and more rapid scarring and a very quick recovery and return to work, there is an inherent danger in its very nature, and that is, if the individual follicles are harvested from a wide area around the donor supply, the end result can lead to something that we have termed a “diffuse donor depletion”. Unlike the strip harvest, which removes a long, defined ellipse with a clear scar, FUE can take out follicles in a very diffuse and wide donor zone and if not carefully and conservatively planned with future stability as the main consideration, can remove follicles from these outer fringe areas of donor that are at best only “temporarily” stable. The result is not a scar but a general decrease in overall density that may not be obvious to the naked eye initially but becomes glaringly obvious over time as the patient’s own donor hair continues to fall victim to his pattern balding and the surgeon has taken most of it out of him in an effort to just meet his current demand for grafts. In other words, in a rush to meet his patient’s current expectations and without thinking long-term, the surgeon will potentially plant the seeds for a real future cosmetic disaster.

In summary, the modern hair restoration surgeon must no longer view the scalp donor area as a static, one-dimensional, infinite bank of follicles. It must be viewed in a dynamic manner as a limited pool that needs to be managed with the precision and long-term vision of a prudent financial planner. The new SDA must move away from the older simplistic concept of a Safe Donor Area to the more fluid and patient-specific concept of a Safe Donor Area for that specific patient at that specific point in his or her life. This shift is paramount and the patient-specific assessment to determine long-term donor stability is key. In addition to a patient’s age, his or her present Norwood stage, detailed family history of balding on both the mother and father’s side, careful analysis for even early miniaturization of the donor scalp under magnification (trichoscopy) and an assessment of the patient’s innate donor characteristics of hair caliber, wave and color contrast to the skin color will lead to a much more individualized “Lifetime Plan”. This plan is not just to correct the loss of the day but rather to more strategically spend the patient’s finite donor over his or her life. In many ways this results in much more conservative approaches much earlier in these high-risk patient’s lives. In the young, at-risk patient this often translates to treating the frontal core very conservatively and sculpting a soft, natural age-appropriate hairline and very often leaving a very large, intact donor bank for future harvests as this young man’s balding inevitably progresses. It is the philosophy of doing less early on to preserve a healthy donor for the long term over the idea of doing more early to satisfy the patient’s current maximum demand for grafts and density. The new surgeon must take on the role of conservationist rather than maximalist and in an era of high patient demand to go “big” on day 1, must at times educate, but more importantly, just refuse, to perform a mega-session and exhaust the donor on the first procedure, leaving a scar that is a lifetime testament to the greed of both the surgeon and the patient and the patient will 10 years down the line end up with an unnatural frontal third of scalp that is full and dense, an almost completely bald crown and a thin, over-harvested donor area in the back and sides.

Another related technical implication is a re-evaluation of how we even define and then map out this new donor area on the scalp. It has been found that one can no longer view the donor zone as a static, homogeneous, safe area but is a more nuanced, multi-tiered risk structure. As a result, mapping the donor area is becoming a lot more advanced. The various regions of the donor are viewed now in many risk categories. The inner, central portion of the occipital scalp is always viewed as the most stable zone, the “fortress” if you will of the donor supply. The area superior to the occipital is now viewed as an area of either intermediate stability or completely variable stability. Extraction of hair from these latter areas in young or at-risk patients needs to be avoided. Examination of these more marginal and borderline areas, including trichoscopic or microscope-based examination to look for even subtle signs of miniaturization, is becoming standard practice in these at-risk patients. A follicle that is 20% miniaturized may not be a “safe” follicle in the long-term even if it looks perfectly healthy to the naked eye.

A final and very exciting consequence of this re-evaluation of the donor area is the physical expansion of the very concept of what constitutes a donor area. When the scalp donor is deemed high risk or simply not enough for the patient’s desired end result, a growing number of surgeons are expanding the safe zone to include alternative donor sites all over the body. Body hair transplantation (BHT), the use of hair from the beard, chest, arms and legs, was until quite recently a technique mostly relegated to high end aesthetic centers and borderline hair transplant candidates with very little or no scalp donor. This is now being used much more widely both as an adjunct to repair work and in cases of severely diminished scalp donor. Hair from these other areas can and often does have different characteristics of growth, texture and caliber from scalp hair and when used judiciously for filling-in the mid-scalp and crown areas of the scalp, these grafts can be a very valuable additional donor supply for the patient and surgeon. Similarly, the role of non-surgical medical therapies, principally topical minoxidil and oral finasteride/dutasteride, has a very important and active role to play in this newer donor area paradigm. While these medications in many ways are viewed almost exclusively as a treatment for the recipient or balding areas in the past, they can also in many cases be actively and aggressively used to try and stabilize or at least freeze the natural progression of pattern loss in the donor area as well. While no medication has ever been demonstrated or even been believed to improve or augment scalp donor, the use of these medicines to simply slow down or stop the progress of a pattern balding can effectively render the SDA to be “safe” in many patients for a lifetime and thus make long-term planning a lot more predictable and safeguard a surgical procedure and its results.

The ethical implications of all of these changes and new concepts are profound. The annals of hair restoration history are unfortunately full of patients who have suffered for decades from the consequences of this one-size-fits-all-outmoded paradigm. The ethical hair restoration surgeon of today has no choice but to not only be a technician but also an educator and in many cases, someone who needs to be prepared to turn away patients or refuse to perform a procedure that in his or her estimation, based on well-established objective criteria, is destined to result in a less than optimum or even poor long-term outcome. The conversation has to shift away from how many grafts can I get, how dense can we go? and focus on what is the best and most sustainable plan for me and my specific pattern of hair loss over the course of my entire lifetime. This will inevitably mean a lot more time and investment in patient education in general and a need to help the patient understand that his or her donor supply is not infinite and that the process of losing hair is a progressive genetic disorder and one that the surgeon and patient will have to live with for the rest of their lives.

In summary, the concept and application of the safe donor area is being rapidly and in many cases, dramatically re-written. It is moving from a simplistic and mostly static model to a more complex and very much dynamic concept of limited donor supply that must be viewed as a precious, finite resource that must be utilized with the long-term vision of a prudent, conservative financial planner. The stability of its current borders, especially in the young and at-risk patient population is now at best a relative certainty. The long-term boundary is becoming a relative not an absolute certainty. The resulting and on-going debate is not an academic exercise. It is a debate that has a very real impact on how the modern surgeon practices, plans and most importantly, counsels his or her patients. It has a direct and obvious influence on surgical decision-making but also has serious ethical ramifications for every hair transplant surgeon and clinic. The modern surgeon must now not only be a technician but also an educator and above all, an ethical counselor. The continued re-evaluation of the Safe Donor Area is part of the maturation process of our specialty and is a necessary one if hair restoration is to continue to evolve and meet the modern patient’s expectations and ever higher demand for follicles and density in a responsible, ethical and professional manner.