DISCUSSION
An ideal ratio is considered when the height of the forehead is one-third of the overall length of the face (from a midfrontal point to the menton) [
2]. However, 1:1:0.9 is the preferred ratio recently that allows a younger-looking appearance; thus, the height of the forehead is often designed slightly higher (5-7 mm) than the bottom one-third of the face (from the subnasalis to the menton).
According to the author’s study (2007), the hairlines of Asian females can be generally classified into one of the following five types (
Fig. 2) [
9]. Round (27%), M-shape (28%), and rectangular (27%) foreheads account for the majority of shapes; these percentages are similar to what Dr. Nusbaum reported regarding forehead shapes for women in the West, including 61% who had a concave, triangular type (corresponding to the M-shape and rectangular foreheads) and 26% who had a concave and oval type (corresponding to the round forehead,
Fig. 8) [
10].
The average measurement of foreheads for Korean women reported by the author is as follows (
Fig. 9):
• Average height of forehead (mid-eyebrow to base of widow’s peak): 6.38 cm
• Average width of forehead (distance between both temporal points): 14.3 cm
• Average depth of the infratemporal recess (infratemporal apex to lateral canthus): 4.29 cm
Nusbaum et al. reported that a widow’s peak was observed in 81% of patients, a lateral peak was present in the midportion between the frontal midpoint and a temporal point, and a temporal point was positioned 1 cm away from a line drawn perpendicular to the lateral canthus [
10].
To correct a hairline, a part-line is one of the important factors that provide a natural appearance. It was observed that 46% of people had a part-line on the left, 14% had a part-line on the right, 20% had a part-line in the middle, and 20% had part-lines on both sides. In cases of an M-shape forehead, a part-line was not clearly visible, since a conventional partline is positioned toward the inside of the frontotemporal recess. After a surgery, a new part-line is formed in a forward location and is thereby clearly visible. The hair on the most-frontal area of the part-line is directed in a radial pattern, so that the scalp is easily more exposed. For this reason, the density of hair around appears to be relatively low after surgery.
Therefore, if a part-line is positioned within the center onethird of the frontal hairline, it would be natural not to correct width more than 1 cm as a new frontal midpoint. If a part-line is positioned at the outer one-third of the frontal hairline, a frontal midpoint could be moved down by 1.5 cm, since the center would be camouflaged well by laterally directed hair.
In cases that part-lines are on both sides, strong part-lines are maintained. If one of the part-lines were weak, a more natural hairline would be visible as the part-line on the stronger side.
In cases that the donor hair has a thick caliber, the volume of the hair in the recipient looks natural initially after transplantation, but it does not look natural later because the thick hair will grow in the transition zone. In this case I try to increase the proportion of 1 hair FU, especially thin 1 hair FUs which were disposed on the most frontal area of hairline zone.
If the caliber of donor hair is thin, a transition zone looks more natural, but the volume of the mid- and apex zones on the backside is decreased, so that it is better to increase the hair density on these zones with 3 & 4 hair FUs.
In cases that the existing frontal hairline zone looks see-through due to innate low-hair density or Hamilton-type female pattern hair loss, enhanced density should be required and can be achieved by adding 2 hairs FU sat into a width of approximately 1-1.5 cm.
A cowlick is a type of part-line which the hair points naturally upward, as seen in 64% of women in the West. It is more common with a cowlick on the left.
When performing hair transplantations in this area, since the hair directs upward, the shivering effect is decreased and the density appears to be decreased. Therefore, It is better to increase the density of 1 hair FU more than 50/cm2 and reduce the height of corrected area within 1cm if possible.
When the forehead is wide, the side of the face appears to be wide due to wide infratemporal area and the posterior location of a temporal point. In general, the shape of the infratemporal line is natural when it is concave in accordance with the curvature of the orbital rim, but it can be designed to a nearly straight line to reduce the infratemporal area or sideface.
When a sideburn is well developed, it can be connected naturally to an infratemporal line. However, when there is no sideburn, sideburn transplantation can be performed at the same time, since the side of the face would look wide without the sideburn.
Unlike men’s sideburns, such hair transplantation should be limited to the level of the zygomatic arch and directed posteriorly and inferiorly. Additionally, it is desirable to make the density below the 20/cm2 and avoid using coarse hairs during the transplantation.
After surgery, the side of the face can be partially hidden or made to look smaller by growing the hair as it is; alternatively, the hair can be swept behind the ears and styled naturally.
For a newly designed forehead height, a new midfrontal point should be determined from the mid-eyebrow at a distance of approximately 5 to 7 mm longer than the lower one-third of the face (subnasalis to menton); the correct width should not exceed 1 to 1.5 cm from the previous mid-frontal point.
From the new mid-frontal point, the hairline begins to draw laterally in a round shape considering the contour of the face and meet the temporal point that is on the line perpendicular to the lateral orbital rim. An infratemporal line should be designed as a round shape in accordance with the curvature of an orbital rim from the temporal point and then connected to the anterior border of the sideburn. The back edge of the transplanted area should be marked with gentian violet to classify the range of the frontotemporal triangle into three zones as follows: 1) a transition zone, which is positioned at the front and has an approximate width of 1 cm; 2) a mid-zone, which is positioned in the middle and has a width of 1.5 to 2 cm and 3) an apex zone, which is positioned in the apical region and has a triangular shape.
To prevent a straight hairline, a zigzag or a snail-tract shape is made, and 8 to 10 clusters, including a widow’s peak and lateral peak, should be designed to avoid symmetrical appearance of both sides.
If the transplantation density was 70 hairs/cm², 2,107 hairs would be required. However, the total hair required for the transplantation should be estimated after considering the additional hair needed for transplantation in the infratemporal and sideburn areas.
The density of the occipital region is calculated by using trichoscopy or densitometry; then, the size of the needed strip is measured by determined length and a width within the ranges of 20 to 22 cm and 0.8 to 1.5 in most patients, respectively.
When the thickness of the patient’s hair is in the average range (60 to 80 microns), the ratio of 1-hair FU:2-hair FU:3- to 4-hair FU should be 3:4:3, but when the patient has thick hair (>80 microns), the transition zone should be deliberately widened by increasing the ratio of the 1-hair FU by 50% to have a natural-looking transition zone. In contrast, in cases of thin hair (<60 microns), the mid-zone should be widened by increasing the ratio of the 2-hair FU artificially to increase the volume of the hair.
Each FU changes depending on the transplanted region. Only 1-hair FU is transplanted to have a natural-looking transition zone and make a dense packing. In the mid-zone, a 2-hair FU is transplanted, whereas 3- to 4-hair FU is primarily transplanted in the apex zone to increase the volume. However, when the density of the FU is decreased in the mid-or apex zone, it can be increased by transplanting a 1-hair FU between them (
Fig. 10).
In the transition zone, the dense packing is needed so that we make a density at 50 to 60/cm² with 1-hair FU. The mid- and apex zones are transplanted at densities of 30 to 40/cm² with 2-hair FUs and 20 to 25/cm² with 3 to 4-hair FUs.
The direction of hair will be most natural to follow the existing hair line along the frontal hairline. In general, temple will show patterns that lower portion will be strongly from inferoposterior direction toward laterally changed to lateral direction, then as approaching to part-line it will again be facing to downward.
The angle of hair will get larger from sideburn toward part-line. It is about 15 to 20 degree up to temporal point, about 20 to 30’ up to supratemporal line, about 30 to 45’ around lateral frontal line, and about 45 to 60’ around central frontal line. It’ll be natural to transplant at 60 to 90’ near to the part-line area.
In Asian patients, a few cases of severe curly hair over the recipient sites were observed. However, they were improved after 1 or 2 years.
In transgender patients (male-to-female transgender patients), as male pattern hair loss progresses, there is a chance of hair loss at the rear of the transplantation site. It is, therefore, necessary to minimize the range of correction required, considering secondary transplantation via a conservative design and confirming sufficient hair in the occipital region if necessary.
If there are scars due to injury, burns, and surgeries, such as forehead reduction or facial lifting, hair transplantation can be done on the scar sites as well; given the lower survival rate of hair in these areas, it is helpful to use the ‘no touch technique,’ which uses a hair transplanting device after making slits for better graft survivals.
Laser hair removal treatment may produce non-natural straight hairline for several reasons: 1) There is no 1-hair FU located at the front of the hairline, and the hairline looks too dense with thick 2-hair FUs are exposed in front; 2) There is a distinctively clear and sharp straight hairline without either a widow’s peak or lateral peaks or 3) A white band of depigmentation appears at the skin border of the hairline.
In most cases, natural hairlines can be recreated by making multiple peaks and clusters and irregular zigzag lines with single hairs on the frontal hairline and correcting the width of the forehead.