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What is Graft?

What is Graft?


Grafting refers to a surgical procedure to move tissue from one site to another on the body,  for hair transplant it is moving the cell or tissue from the donor area or site to the area to be transplanted.

How many grafts do I need to have a hair transplant?

This is one of the most frequently asked questions in hair transplant operations, and very few surgeons really carefully analyze the amount needed. To evaluate the amount of hair needed, several aspects must be taken:

  • You must know the degree of hair loss.
  • Age
  • Donor area density
  • Number of hairs per follicular unit
  • Contrast between hair and skin color
  • Characteristics of the hair (color, thickness, wavy, texture, etc.)
  • Predicting the degree of future hair loss
  • Expectations

Depending on all these factors, an approximate amount of hair needed can be recommended, as well as determining whether it can be performed in a single procedure or in consecutive sessions. It should be noted that the number of hair to be transplanted generally reflects an estimated amount of the total hair that can be transferred and is applicable to each patient individually. The impact of a transplant depends on the area to be transplanted and the number of follicular units used.

What is the difference between hair and graft, follicular units?

The term follicular unit represents a natural grouping of hair that emerges from the same pore of the skin. Seen in a stereoscopic microscope, the follicular units are made up of 1 to 3 hairs, and share annexes (the roots of a single follicular unit share the same sebaceous glands, erector hair muscle, etc.). Wanting to cut or separate this follicular unit damages the main structure, and prevents that follicular unit from growing again. Follicular units are found naturally on the scalp. There are follicular units that contain only one hair, while there are follicular units that contain two hairs, and others have three hairs that emerge from the same pore of the skin (sometimes, there are patients who have a follicular unit of four hairs). In an evaluation for a hair transplant, the term hair or follicular units can be used to quantify the needs of each patient. For mathematical purposes, each follicular unit contains on average 2.2 hairs .Therefore, 1,000 follicular units contain approximately 2,200 hairs.

How are the areas defined, and how much hair is necessary?

To quantify the amount of hair, the term follicular unit will be used frequently, since this is what determines the density per square centimeter that can be achieved.

We will separate the head area into two areas: front area (1) and rear area (2). The frontal area is divided into two sections: frontal line or hairline (1), and central area.

The average number of follicular units per square centimeter required to produce density varies from person to person. In general terms, the normal density of an individual is between 80 to 100 follicular units per square centimeter (FU / cm2). Studies have shown that baldness is not apparent until a little more than 50% of normal density is lost. Therefore, a density from 40-50 to 100 FU / cm2 will look aesthetically good, while at densities when a lack of hair is already beginning to be observed.

For example:

To cover an area of ​​50 square centimeters, each square transplanted with 50 follicular units:

50 FU X 50 cm = 2,500 follicular units to achieve a density of 50 FU / cm2

How do I know how many square centimeters (or squares) I need?

To know exactly how many square centimeters of surface area you need, you can draw a 10 X 10 centimeter grid on an acetate (or transparent paper) and place it on the scalp. With the help of a marker, draw the area on the acetate where you see that there is a lack of hair or density (sometimes it is difficult to draw on the acetate, you can do it with two mirrors or with the help of someone). To find the number of follicular units you require, just count the number of squares and substitute the number of centimeters in the above equation for the number of squares.


20 frames 50 FU X 20 squares = 1,000 follicular units at a density of 50 FU / cm2

The density of 50UF / cm2 is a standard for our “no touch technique” technology. Depending on your needs, and considering the area to be treated, the amount of donor hair, the patient's expectations, and considering future hair loss, you can decide if you require a lower or higher density than the one proposed.

The posterior area or crown

This area is one of the most difficult to quantify due to its circular pattern. The easiest thing is to count the number of squares (or centimeters) using a sheet of How do I quantify the frames that still have hair?

The criterion of knowing if there is half the density in these squares to determine if these squares are multiplied by 25 missing FUs is difficult. Since you have to place hair in these areas as well, you have to quantify them with either half the density or less. If you are not sure, a quantification of 25 to 30 FUs per frame can be useful to give an estimate.

Why are they multiplied in the example by 50 UF per square centimeter?

The 50 follicular units is a standard example, but here is the reason why I chose the 50 FU / cm2

It has been seen in world studies that a person normally has a density between 80 and 120 follicular units per square centimeter. This is on average, there are people who have more, and others less; therefore, a person who has not yet experienced hair loss has an average of 100 follicular units per square centimeter. Now, studies also show that when a person begins to notice a lack of density in any of the areas of their scalp, it is because they have lost approximately 50% of their hair. This has been evaluated and accepted by hair restoration associations worldwide.

It can be said then that to give density to an area of ​​the scalp, it is necessary to transplant 50% of the original hair, that is, 50% of 100 follicular units (average). From there we take an average of 50 UF / cm2 to assess the amount of hair needed for each area.

It is also prudent to mention that the number of follicular units also depends on the number found in the donor area (s), so each case must be evaluated individually. In case there is a limited amount of hair available, it is prudent to reallocate different densities in each area of ​​the scalp. Each patient's preference and the doctor's experience will help you decide the best option for restoring your hair.

Because the surgery is permanent, the surgeon must take into account an appropriate capillary design for the entire life of the patient and will also take into account the hair reserves in the donor area. It is for all these reasons that we consider that some very young patients are not good candidates for hair transplantation. In contrast, a mature patient, with significant hair loss, will be much happier with the approach of a restored high frontal hairline and a modest and sufficient amount of hair for the first time in years. Now, the vast majority of patients who consult are between these two extremes, and it is here that the professional has to carefully guide the patient to make him understand the goals that we are going to achieve and the effectiveness of the process. Considering human psychology, capillary dynamics and practical experience, it is not always wise to recommend a specific number of grafts as if this number were an absolute quantity. The amount is indicative, and if possible above what can reasonably and safely be done, but always within the margins. If the evaluation is good, the required precepts are given, we have a sufficient donor area and the patient wants to achieve a high density, of course we will work with high density. The goal of the hair professional is to help the patient understand how close they can be to meeting their personal needs and expectations, how much the entire hair transplant process will cost, and how many hair transplant sessions they may need.

With the right approach, satisfaction is easy to achieve. The effect of a hair transplant counts on the area to be transplanted and the number of grafts used. However, it is still helpful for the patient to have a fairly accurate general idea of ​​the number required in the procedure.

If you have any questions about how to obtain the number of follicular units needed, or how to calculate the area, write us an email and we will gladly help you.

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