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Hair Transplantation


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Planning  |   The Procedure  |  Aftercare  |  FAQs
Donor Harvesting Techniques:  Unified Donor Harvesting vs. Follicular Unit Extraction


General Principles

Individuals have a permanent rim of hair that runs along the sides and back of their scalp. This rim has less exposure and sensitivity to the hormones that cause hair loss. With few exceptions, hairs contained in this rim are permanent and can be used as donor hairs. Hair restoration surgery relies on the principle of donor dominance, namely that donor hairs continue to grow when they are transplanted to balding scalp. Thus, in hair restoration surgery, we simply move permanent hairs from donor areas to balding areas.

dr mark unger toronto hair transplantation

Planning for the Procedure

Planning is the most important element to successful hair transplantation.

It begins with an understanding that the size of a donor area decreases with time, while the size of a recipient area increases. Consequently, one should make conservative estimates of the size of the permanent donor rim, so as to reduce the likelihood of transplanting impermanent hairs. Similarly, one should transplant into evolving areas of hair loss in the recipient area, in addition to areas of more immediate concern. Equally important, it requires an understanding that good cosmetic results should not draw undue attention.


The Procedure

  • First:

    On the morning of the procedure, the treatment plan is reviewed. Thereafter, patients are given medications to help them relax, such that the majority of patients sleep or drowse throughout the procedure.

  • Second:

    In the first step of the procedure, the scalp is numbed. Donor tissue is removed by Unified Tissue Harvesting (UTH) or Follicular Unit Extraction (FUE), with the former technique used more frequently than the latter.

  • Third:

    Follicular Unit Grafts (FUG), consisting of single or multiple hairs, are then prepared from harvested donor tissue. A pattern of small sites is made to fit these grafts. These are made at the same angle and direction as existing hairs in order to create a natural appearance. This is the most challenging technical element of the procedure and the key artistic step.

  • Fourth:

    After the recipient pattern has been created, hairs are placed in the sites. The finest, single hair grafts are used at the periphery of the transplanted area to create a natural appearance, while grafts with multiple hairs are used more centrally to improve density.


Aftercare (Post-op)

Initial Care

Patients return the morning after the operation for an initial visit. They return 7-10 days later for a final visit, and if they had unified tissue harvesting, to have their sutures removed.

Post-operative discomfort is minimal and noticeability is rarely a problem since neither the donor nor recipient area is shaved. In the donor area, nothing is visible after the operation, as the area is well camouflaged by hair. In the recipient area, small crusts can form around grafts shortly after implantation. These may or may not be noticeable, depending how much existing hair is present at the time of the operation. There can be swelling after the operation, and the degree of swelling is often the determining factor in whether there is any post-procedural noticeability. For that reason, we suggest that patients take 7-10 days off of work and social engagements if they wish to avoid questions.

Hair Growth

Short, transplanted hairs are visible immediately after the operation. These hairs occasionally grow, but more commonly fall out four weeks after the operation. Hairs begin regrowing four months after the procedure. Noticeable cosmetic changes are evident six months after the operation, but there is continuing new growth for up to one year after the operation, at which time the final result can be assessed.



dr mark unger hairline example
dr mark unger hairline example
dr mark unger hairline example

Donor Harvesting Techniques:

Unified Donor Harvesting

Unified donor harvesting (UDH) is a method of donor hair harvesting wherein donor tissue is removed as a single piece of tissue containing multiple follicular units. A team of experienced staff then isolate individual follicular unit grafts (FUG) from this tissue. After healing, patients have a thin, linear scar that is undetectable unless the scalp is shaved. With future surgeries, the existing donor scar is excised as part of any new tissue harvesting, such that patients only have a single scar, even after multiple operations. 

Our ability to obtain minimal scarring is related to our conservative treatment philosophy. We are willing to accept a lower number of grafts in exchange for less wound tension, which is the major determinant of healthy wound healing.

We use unified donor harvesting for the majority of patients, since in contrast to follicular unit extraction there is less visibility during the perioperative period, less tissue trauma (UDH with a 24 cm long incision creates 48 cm of incisional length, whereas the FUE of 2000 follicular units with a 0.9 mm punch creates 565 cm of incisional length), less scar tissue (UDH with a 24 cm long incision creates 2.4 cm2 of scar tissue, whereas the FUE of 2000 grafts with a 0.9 mm punch creates 12.72 cm2 of scar tissue), better graft survival (medium trimmed grafts have reported survival rates 80-98%, whereas skeletonized grafts have survival rates of 48-69%), and most importantly an ability to confine donor harvesting to the safe donor zone.


Donor harvesting is confined to the safe donor are even as the area of balding expands


Donor Scars Post-Procedure:

Donor scar area post-procedure

Donor scar area post-procedure

Donor scar area post-procedure

Donor scar area post-procedure


Follicular Unit Extraction

Follicular Unit Extraction (FUE) is a method of donor harvesting, where follicular units are removed individually from the scalp in a single step procedure. In contrast, unified donor harvesting (UDH) is a two step procedure with a large piece of tissue containing many follicular units is removed from the scalp in the first step, and individual follicular units are isolated from the tissue in the second step. After healing, patients have small circular scars in the donor area, but in contrast to UDH the hair can be clipped somewhat shorter.

follicular-unit-extraction dr mark unger hair transplantation toronto

In our practice, FUE is used for patients who are treating isolated scars on their scalp (from trauma or previous hair transplantation surgery) or for patients who do not have enough scalp elasticity to permit unified donor extraction.

Follicular Unit Extraction is not our preferred approach, since in contrast to unified donor harvesting, it is associated with more tissue trauma (FUE of 2000 follicular units with a 0.9 mm punch creates 565 cm of incisional length, whereas UDH with a 24 cm long incision creates 48 cm of incisional length), more scar tissue (FUE of 2000 grafts with a 0.9 mm punch creates 12.72 cm2 of scar tissue, whereas UDH with a 24 cm long incision creates 2.4 cm2 of scar tissue), and poorer graft survival (skeletonized have survival rates of 48-69%, whereas medium trimmed grafts have reported survival rates 80-98%).

Most importantly, in order to obtain a sufficient number of grafts, most practitioners usually harvest grafts outside of the safe donor zone. For that reason, FUE is most appropriate for patients who require a small number of grafts.

folliular extraction unit low donor harvesting area

Donor harvesting has a higher risk of exceeding the safe donor as the area of balding expands


Frequently Asked

+ Is it safe?

The procedure is extremely safe. In our practice there has never been a serious complication, either during the operation or following the operation.

+What hair loss conditions can be treated with hair transplantation?

The most commonly treated conditions are male and female patterned hair loss. However, hair transplantation can be used to treat other hair loss conditions, such as scarring hair loss, provided that patients have a suitable donor region.

+Do I need to be bald to have a hair transplant?

No. Our preference is to operate earlier, before individuals are profoundly unhappy with their hair loss, and at a time when the procedure can be easily camouflaged. It is possible to add hair to thinning regions of the scalp, without harming existing hair, if grafts are placed carefully at the same angle and direction of existing hair.

+Do I have to be a certain age in order to undergo hair transplantation?

No. Individuals should consider a transplant at any age if they are bothered by their appearance. Younger individuals often have a milder degree of thinning, but the impact of hair loss, although significant at any age, is potentially more emotionally taxing, and thus the need for treatment is proportionally more important. Although younger patients often want aggressive treatment with high density graft placement, paradoxically they need a more conservative surgical plan. Just as there is no minimum age for undergoing the procedure, there is also no maximum age limit. If you're bothered by balding, the problem can be corrected.

+Can women have hair transplantation?

Yes. A large percentage of women suffer from hair loss, and frequently they are excellent candidates for hair restoration surgery.

+Do you guarantee a certain number of grafts?

No. We can provide an estimate of how many grafts we expect to harvest, but surgical variables influence the final number of grafts that are harvested. Adhering to a precise number runs the risk that physicians alter their surgical plan based on an abstract number, rather than conditions on the day of surgery.

+How many grafts are transplanted during surgery?

In a single session, we typically transplant between 2000-2500 follicular unit grafts in males and 1000-1500 in females. This number of grafts produces a notable cosmetic improvement, while off-setting certain risks. Larger, so-called megasessions, permit treatment of an expanded area of hair loss in a single session, but increase the risk of potential complications in both the donor and recipient area.
In the donor area, harvesting a larger number of grafts is associated with different potential complications, depending on the harvesting technique. Using unified donor harvesting (UDH), physicians tend to excise wide sections of tissue in order to obtain a larger number of grafts. This increases the closing tension of wounds, thus increasing the likelihood of wide scarring or the wound reopening. In contrast, with follicular unit extraction (FUE), physicians tend to stray outside of the safe donor zone in order to obtain the required number of grafts, thus potentially transplanting impermanent hair.
In the recipient zone, larger sessions are similarly associated with a higher risk of complications. First, the cumulative incisional area of larger sessions can result in poorer graft survival. As an example, if 3000 FU are transplanted into a 1 mm long recipient-site incision, then the total recipient incisional area is 3 meters. In our experience, this large an incisional area results in poorer graft survival. Moreover, patients are at greater risk of developing the serious, but rare, complication of recipient area necrosis, wherein no grafts grow, or of severe hair shedding after the operation.

+How dense are grafts placed?

Grafts are usually transplanted at a density of 30-35 follicular units/cm2. This strikes a balance between providing cosmetic density, while preventing the use of excessive numbers of grafts in a finite region. Mathematically, it is impossible to restore full density to thinning scalp without compromising on the size of the treated area. In other words, there is no such thing as a free lunch. While older individuals with small areas of thinning are candidates for higher density planting, this should be avoided in younger individuals given the uncertainty surrounding the eventual size of their recipient and donor areas with the passage of time.

+Will I need to shave my head for the procedure?

No. While a longer hair length increases the time that it takes to perform the procedure, at the same time it makes it easier to follow existing hair patterns, and in that way helps produce a more natural result. Equally important, it provides camouflage for the procedure so that there is considerably less visibility in the post-operative period.

+Are transplanted grafts visible?

Hairs are implanted the same way they were removed, as individual follicular units, and thus the results always look natural. This is in contrast to older techniques, whereby larger grafts could be observed as unnatural clumps of hair.

+How many operations do I need?

Over a lifetime, most individuals require multiple sessions, but it depends on patient goals, the size of the initial surface area that needs to be treated, and the size of the progression of thinning over time. We often conceptualize the scalp as being composed of a "frontal" area extending from the hairline to a line drawn between the ears, a "midscalp" area extending from the frontal area to the point where the scalp changes from being parallel to the ground to sloping perpendicular to the ground, and a "vertex" area that extends from the midscalp to the hair fringe at the back of the head. Most individuals need treatments to the frontal and midscalp regions at minimum. In this way, they look as though they have a full head of hair from the front and the sides. However, if they want the crown treated as well, then additional transplantation is needed.