Hair Transplantation Basics

Hair transplant is a surgery which relocates the permanent hair to the bald/thinning areas.
After the relocation of the grafts, the hair will keep growing. It will have the same characteristics as the hair from the donor site- size, quality, growth speed and the same lifespan. If you have hair from the donor area at the age of 90, the transplanted hair will keep growing into your 90’s too. That’s the beauty of hair transplant.
However, because it is relocation of hairs, it does have some limitations too.
It is a growth of one to one ratio-if we transplanted 1000 hairs, it will only grow 1000.
The total number of the hairs will not have any change. It will increase the number of hairs at recipient site but there will be the same number of hair lost from the donor site. The total number will not have any changes at all.
We are only able to guarantee that the transplanted hairs will be permanent, but any natural existing hair will not have any guarantees. It’s unrealistic to expect no further hair loss will occur, even after a procedure. A hair transplant cannot prevent future hair loss.
Finally, if you are young and have active hair loss, then prevention of further hair loss is very vital. A hair transplant can’t help this but medication can. Patients must seriously consider taking the medication after the surgery.

Hair Transplantation Basics FAQ

What is a modified follicular unit?

The picture above is an example of a donor strip taken from the back of the head. The red section outlines a modified follicular unit, while the blue section outlines a standard single follicular unit. As shown in the picture above, you can see that hairs tend to clump in areas of 1, 2, 3, or even up to 4 hairs. These clumps of hairs are called single follicular units. For hair transplantation, follicular units of hair are separated from the donor strip and divided into units of hairs called grafts.

At NHT Medical Center, we utitlize the combination of three different sized grafts– single hair follicular unit, single follciular unit, and the modified follicular unit. Modified follicular units are grafts the size of about two single follicular units combined. However, we do not make modified follicular units bigger than 4 hairs. Using modified follicular units can yield up to two times as many hairs than using normal single follicular units.

The purpose of using single follicular units is to obtain a natural look. For the hairline, we still use single follicular units and even single hair follicular units. We agree that those are the best options for the hairline. But for density purposes, we prefer to use modified follicular units for the coverage of the rest of the area. Modified follicular units provide a thicker, fuller appearance, and are more suited to the non-hairline regions of the scalp.

Are Single Follicular Units the Best Graft Size for You?

A. Hair transplantation has advanced due to the change in graft size. Since 1995, the New Hair Institute group introduced the concept of the follicular unit. Now when we discuss the size of a graft, follicular units are the most popular and prominent ideas. Almost everyone believes that follicular units are the best size grafts for hair transplantation, but are follicular units really the most suitable size graft for the patient?

Some people use follicular units as a means for comparison between different clinics. Now, 8 years after the concept of follicular units was introduced, a lot of clinics even have to claim that they only perform 100% follicular units to help persuade patients. The following information will take a closer look to see if it really is in the best interest of a patient to do a 100% follicular unit procedure. First, let’s take a look at claims some doctors use to convince patients that follicular units are the best choice.
Claim #1: The wound size of individual follicular units can be kept to a minimum because larger wounds can make the healing process slower and often causes irregularities to the skin surface.

Claim #2: Multiple follicular units require the recipient skin to be removed via punch or laser.

Claim #3: Non-hair bearing skin consists of about 50% of the donor site. Removing the non-hair bearing skin will have a substantial effect upon the outcome of surgery.

Claim #4: Hair grafts larger than a single follicular unit will cause a pluggy, tufted look.

B. In our surgical center, we use 3 sizes of grafts: single hair follicular units, follicular units, and modified follicular units. We use single hair follicular units and follicular units for the hairline only, while modified follicular units are the basic size for the rest of the grafts. Why use modified follicular units instead of single follicular units? What are the advantages of it?

Response to Claim #1 (We wrote this in 2002. Physicians have started using self-made blades now, so this part will be updated soon.)

To make slits for a single follicular unit, most physicians use an 18G needle with a diameter of 1.26mm. A few physicians use the 19G needle with a diameter of 1.08 mm. Therefore, 2 slits from the 19G needle would be 2.16 mm. In our clinic, however, we use the SP91 blade, which creates a slit length of 1.97mm, and also allows one slit to hold two follicular units (one modified follicular unit). Please compare below the length of wound size for a 1000 graft procedure.


Diameter (mm)
Length of 1000 Follicular Units
B.D. Needle
1080 mm
Deeper than Follicle length
B.D. Needle
1260 mm
Deeper than Follicle length
Mini Blade
985 mm
Exactly follicle length

graft_1For the 19G needle, 18G needle and SP91 Mini-Blade, the length of the wound size of 1000 grafts would be 1080 mm, 1260 mm and 985 mm respectively. The SP91 Mini-Blade has the shortest size of wounds, and, therefore should have a quicker healing period.

Additionally, when we mention wound size, we should mention both the length and the depth. For hair transplantation, the depth is especially important. Please see the picture. The microcirculation is just beneath the hair follicle; too deep an incision would unavoidably damage it. To allow the growth of new implanted grafts, we should reduce the damage of the surrounding tissue to a minimum.

graft_depthgraft_2The 19G and 18G needles cannot control the depth of incision, so there is a high chance that the incision will be too deep or too shallow. If the incision is deeper than the hair bulb, it will most likely puncture the microcirculation. On the other hand, if the incision is too shallow, then graft insertion will be very difficult, if at all possible. With the mini-blade, however, we are able to set the length of the blade to exactly the right size we need (as seen in picture), so there is more control of the depth of incision.

Response to Claim #2
We use a mini-blade (not laser, not punch) to achieve our high level of results. There is no extraneous tissue removed. However, for physicians using the 18G and 19G needles, tissue may occasionally be removed because of the small holes that are in the middle of the needle. The needle works as a puncture, and therefore, might unnecessarily remove tissue from the scalp.

Response to Claim #3

graft_3Please view the photo of the donor strip. We can see non-hair bearing skin makes up at least 50% of the strip. As learned from other studies, more than 10% of the hair is invisible because they are at the resting phase. When you remove any of the non-hair bearing skin, you automatically lose this 10% of hair.

There is one report, which came from Dr. Kolasinski in Poland Nov 2001. In his study, he reported that he had transplanted 15 non-hair bearing grafts— no visible hair follicles— in a patient. 7 months post-operative, there was a re-growth of 35 hairs from these grafts. Amazingly, each non-hair bearing graft yielded about 1 to 3 hairs per graft. From the results of that study, we can conclude that the best hair transplant procedures are the procedures that transplant 100% of the donor tissue to the recipient site without removing any of the tissue. Non-hair bearing tissue today does not mean that there is no hair in the tissue at all, but just that the hair is not clearly visible.

Response to Claim #4
Our basic graft size- the modified follicular unit- is double the size of a single follicular unit. Please see our results in the zoomed-in photos and videotapes. Do they look pluggy or unnatural? Undeniably, the size of the graft is a big factor concerning a pluggy and unnatural look. But a more important factor is the uneven distribution of grafts and very large empty spaces between the grafts. Even for a 100% single follicular unit transplant, if the grafts are not close enough, the results will still look pluggy.

For the past ten years, we have repaired hundreds of pluggy-looking patients. For patients with the older 4 mm grafts, instead of removing these pluggy grafts, we only fill in the empty spaces between the grafts as much as possible. Please see the pictures for an example of our results. (The only exception is when the pluggy hairline is too low. Then we may have to remove some pluggy grafts).

If you were able to fill in all of the empty space between the grafts and achieve equal density everywhere, then even if you don’t remove any of the big plugs, the pluggy-look will disappear. This is the principle that we have been using for correction of the unnatural pluggy appearance.

C. Contradictions for Follicular Units
For patients with curly hair or white hair, we especially do not recommend the practice of only using single follicular units. The reason for this is that curly hair is not only curly on the outside, but even the hair stem within the tissue is curly. It is extremely difficult to avoid damage to these grafts. The more one cuts the strip, the more damage one will make. White color hair poses a different problem because it is extremely hard to see even under the microscope. The reason for this is that white hair is the same color as the tissue. Just like writing with black ink on black paper, no matter how much you enlarge a white hair donor strip, it will still be very difficult to see. Even under the microscope, white hair is not clearly visible. Therefore, the more grafts that you cut from a curly donor strip or white donor strip, the more risk of damage you will incur.

D. Conclusion

The purpose of using single follicular units is to obtain a natural look. For the hairline, we still use single follicular units and even single hair units. We agree that those are the best options for the hairline. But for density purposes, we prefer to use the modified follicular units for the coverage of the rest of the area. Our conclusion is that for the hairline, we should use single follicular units or even single hair grafts to achieve a natural look. But for the rest of the area, we should use modified follicular units to achieve more density. The final goal for a hair transplant is the combined result of an undetectable hairline and added density for the other areas.

What is the final goal for a hair transplant?

There are two goals of hair transplantation.

1. Natural Results

Natural results mean that it is undetectable to the human eye. No one will be able to detect that you ever had a hair transplant surgery done.

2. A Balanced and Harmonious Look

To achieve this, we should have the same volume of hair in all regions. This means that the donor site and recipient site both have the same density. A lot of hair transplant experts know that, because of illusions from the human eye, it is difficult for people to tell the difference between 50%-70% and 100% density.

Based upon this knowledge, we only have to deliver 50%-70% added density to a recipient site to achieve a look of full density. (However, this also depends on age, expectations, and the contrast between the color of the hair and skin, so some adjustments may be needed)

What we mean by 50% to 70% Density?

The goal for hair transplant is to increase density and look natural. Today, the size of graft is very small and we can transplant very closely without any problem. A natural look can be easily achieved, so the only problem is the density.

Ninety percent of the patients will be satisfied by 50% to 70% of donor site density. Since human eyes cannot tell the difference between 50% -70% and 100% density, therefore, after we reach the 50%-70% density goal, the donor site (100% density) and recipient site (50%-70% density) should look very natural and harmonious.

Our final goal for the hair transplant is to reach a 50%-70% donor site density.

If you have a completely bald area, it may take two or three surgeries to cover. If you have an area partially covered with hair, it may take only one surgery to fill in the area.

For large area, we increase 25% to 35% of the donor’s original density in each surgery. After two surgeries, the density is at about 50 to 70 % which is often adequate coverage to satisfy the patient. The time between each session is usually four to six months in order to see how the hair is growing out and to provide more equal distribution.

For smaller area in hairline region, we can increase 45% to 50% density in one surgery.

We use an easy way to ensure that you will receive the promised donor site density.
Here is an example:

If we want to transplant 35% donor site density to cover a balding/thinning area of 80-cm2, we need to remove a 28-cm2 strip of donor skin. (80 cm2 x 35% =28 cm2)

We then divide the 28-cm2 strip of donor skin into small grafts and implant them to the 80-cm 2 coverage areas. This way you will receive a 35% density increase in the recipient area.

How many grafts do I need?

How many grafts do I need? (Read this before you go for a consultation.)

To know the surgery cost you have to know:
1. the coverage area
2. density
3. donor size = coverage area x density
4. number of graft.

1 cm square ~200 hairs ~100 single follicular units ~100 grafts

Other hair transplant clinics’ surgery fee= price per graft x graft number

our surgery fee= price per sq. cm. x donor size

Example #1:

coverage area:100 cm square. increased density 25%.
The donor size needed is
100 cm2 X 25% = 25 cm2
so 25cm square = 5000 hairs = 2500 SFU

Example #2:

coverage area:80 cm square. increased density 30%.
The donor size needed is
80 cm2 X 30% = 24 cm2
so 24cm square = 4800 hairs = 2400 SFU

Example #3:

coverage area:60 cm square. increased density 35%.
The donor size needed is
60 cm2 X 35% = 21 cm2
so 21cm square = 4200 hairs = 2100 SFU

If you still have calculation problem please complete the online consultation form.

Our Belief

When we receive hair transplant surgery, we expect the transplanted hair quality to have the same quality as the donor hair, grow at the same speed and last as long as the existing donor hair.

The human body is so complicated, even with medical science as advance as it is today, we still don’t understand it completely. Something that works today, may be the poison for
tomorrow. It happens so often. Recently, the news reported that red wine increases the chance of breast cancer is a great example. Just two years ago everyone was so excited about its benefit to the cardiovascular system. We all know our donor hair is limited, but how to take full advantage of it is essential.

Especially for hair transplantation. The study is always based on a very small sample and personal observation. A lot of times even without any study at all. For example, body hair transplant. When it was brought out by a few doctors , patients jumped on it right away, now we found the result is such a disappointment, it failed miserably( beard might be the exception).
Let alone to mentioned eyelash transplant. Even the most popular single follicular unit transplantation. A few doctors had some study to compare the growth rate( quantity study) of chubby and skinny graft, but never have anyone to do quality study (compare the size of transplanted hair). Let alone to compare the result of single and bi follicular units, or the impact of transplanted hair 10 or 20 years later. (except we have one observation )

There is so much uncertainty in this cosmetic surgery. Our approach is to do a lot of research for new techniques and conservatively adapt some of them which has apparent advantage. For example, it took me two years to visit several of the most famous hair transplant physician’s offices when I started my hair career 25 years ago. I even spent $50,000 USD and one month to fly to Australia to learn scalp reduction from the best doctor for it, but after I learned about it, I never used it for any of my patients, and I am very happy about it. Time proved that I was right , scalp reduction is not the best for the patients benefit. Recently, I learned about the latest Artas Robotic. I flew to Denver twice to see its operation and visited it’s headquarter in Mountain View California. ISHRS has had 25 annual meetings and I attended 21 times. They are the best learning opportunities, not only from the meeting presentation, but also from the personal communication.

We adopted a lot of new techniques at the same time we gave up a lot of new approaches in the last 25 years. I will discuss it one by one in the near future.
For example almost 99% of hair transplant clinic’s use single follicular units exclusively, but we still insist different people, different situations, need different size grafts. Have you
ever heard any one exclusive surgery alone always the best way to treat certain disease. No, absolutely not. Why hair transplant is different?

We improve our technique all the time but our method is not necessarily the most popular or the latest one.

FUE is a good example, it’s so popular now and we receive many inquiries every week. After serious consideration we decided to put a hold on it, because the quality of grafts are no comparison to ones cut under the microscope direct Vision and So far not any quality and quantity study was done yet. In addition to it, it’s only advantage is no donor scar, This can also be achieved with a very simple method. We just don’t believe it is for the best interest of the patient.

NHT Phiosophy

NHT Treatment Strategy

The dilemma that we face in hair transplant surgery is that the size of our head stays the same while hairs gradually fall out when aged. Less hair to cover same size of the head means reduced density. A patient may not satisfy from the hair transplant surgery because he can never achieve the same hair density that he had when he was young.

So, what treatment strategies do we have?

  1. Transplantation– Because of illusions from the human eye, it is difficult for people to tell the difference between 50% and 100% density with adequate hair length. Based upon this knowledge, we only have to deliver 50% added density to a recipient site to achieve a look of good density. This means that 1 cm2 of donor is able to cover 2 cm2 of recipient area and looks same density. (However, this also depends on age, expectations, and the contrast between the color of the hair and skin, so some adjustments may be needed)
  2. Medications– May help to grow new hair and prevent further hair loss. There are two FDA approved medications for hair loss. But they do not work for everyone and never work for the frontal/ hairline region. Medication only works when you are on it. After discontinue taking the medication, the hair grew back will fall out again in a few weeks.
  3. Target the right location for hair transplant to get best visual effect. We emphasize the most important area such as the frontal area and the area where you part your hair. We do not transplant same density on the whole scalp.
  4. Camouflage
  • Blow your hair and use Volumizing Foam
  • Perm you hair so the curly hair can grow longer to cover more area and looks fuller
  • Color your hair to reduce the color contrast between hair and skin
  • Part your hair from the side or comb hair to cover the vertex area
  • Use hair powder or cream to reduce contrast
  • Use hairpieces temporarily

5. Leave vertex empty-For patient with huge area or is very young, we may leave the vertex area alone to conserve limited donor hair.

In many cases, we have to combine several strategies to give the best result.