Keywords
ratio method in hair transplant - divine permanent zone - permanent donor zone
Introduction
Hair loss is a common problem with androgenetic alopecia being the most common type.
It is characterized by progressive thinning of the scalp hair and a reduction in hair
density and diameter.[1]
Most patients experiencing hair loss, lose hair from the hairline, bitemporal regions,
and the frontal region, or if from the vertex, the anterior margin is first.[2]
The first hair transplant was performed by Orentreich[3] who suggested the theory of “donor dominance,” which stated that the transplanted
hair keeps the original nature of the donor site even after being transplanted. Donor
dominance theory of Orentreich and the definition of a safe donor area are the theoretical
foundation of modern hair transplantation.
The safe donor area is defined as an area in which no progression of permanent androgenic
hair loss occurs.[4]
Knowledge of safe area is important so that the hair harvested for transplantation
does not fall off and the harvest remains in the permanent zone. A number of authors
have reported how to estimate the safe area, but we feel that the estimation is not
tailored to every patient. In patients who do not have advanced stages of hair loss,
the margins of the safe zone are assumed to be free from future hair loss at the vertex.
In other words, there is no way to predict the exact dimensions of the safe zone for
every individual.
Our study is an attempt to find and establish a relationship between the safe zone
dimensions and other standard dimensions of the scalp, and to be able to predict the
complete safe zone effectively in patients with early stages of hair loss.
Materials and Methods
The study was conducted in 200 patients presenting for hair restoration in a private
center in India, from July 2022 to December 2022.
Patients with diffuse, unpatterned hair loss, and miniaturization in occipital scalp
were excluded.
In the first 100 patients, patients with Norwood IV ([Fig. 1]) onwards of hair loss were included. The permanent zone was drawn by marking a 2-inch
area over the occiput, and in between two vertical lines drawn from the ears cranially
(axis of pinna). This is the method we currently use. A line is drawn at the level
of occiput, and then the cranial marking is made 2 inches above this line.
Fig. 1 Pictorial representation of Norwood classification.
Then, the distance between the vertex (point A) and the point of change in occipital
hair quality and density was measured (point B), and from this point till occipital
protuberance (point C) were taken. The total distance (points A to point C) was measured
([Figs. 2,3,4]). The ratio between the two (BC/AC) was taken and data was tabularized ([Supplementary Table 1], online in the online version).
Figs. 2, 3, 4 – figures showing. Point A- Vertex, Point B- point where density and quality of hair
in occipital region change, Point C – Occipital protuberance. These figures show variability
in dimension of permanent zone and this is why one design does not suit every patient.
Vertex is the superior most point of the skull, and occipital protuberance is defined
as the highest point of the posterior part of the skull.
Hence, the vertex was the starting/cranial most point and occiput was the ending/caudal
most point.
In the next 100 patients of Norwood II to IVa grade of hair loss were selected and
the applicability of the new ratio to assess the permanent zone was used. The ratio
was implemented to estimate the permanent zone in patients without a clear cut demarcation
of the permanent zone ([Supplementary Table 2], available in the online version).
The zone was designed with the caudocranial direction calculated from the ratio, the
marking of the zone curving toward the ears, 2 cm above the ears.
These patients were followed up closely for 10 months to see the longevity of the
hair and final results. The study is an ongoing study to see the long-term results
for hair transplant; the 10-month period is taken as it is the time when patients
are told to see their final results.
Results
The ratio method takes into account the patient's measurements, that is, permanent
zone and total distance from vertex occiput.
The ratio range we got is:
Permanent zone (BC): total distance from vertex to occiput (AC): 0.43–0.53
Therefore, the permanent zone would be equal to
= total distance from vertex to occiput × 0.43–0.53.
With the lower limit being the occiput.
The dimensions received after using this formula were used to predict the craniocaudal
dimension of the permanent zone. Note that 0.43 was used for patients with family
history of advanced hair loss and 0.53 was used for those who did not have the same.
Ratios have been fixed at two values for ease of applicability, the highest and lowest
values received were used as the average was not representative of the entire group,
the higher value was used for patients with weaker family history of progressive baldness
and lower value was for patient with stronger family history. This was done to avoid
accidental erroneous use of a higher value (like mean) in patients with an actual
low ratio value.
Note that the ratio 0.43 was used for a total of 41 patients and 0.53 for 59 patients.
All of our patients receive only platelet-rich plasma and no adjuvant medications
like minoxidil or finasteride were given.
These results are tabulated ([Table 1]). The presence of hair was checked by the density in 1 × 1 cm area, by trichoscopic
assessment in two separate areas, a pictorial comparison, and patients' input, after
10 months of the procedure. Any reduction greater than 10% was noteworthy and results
were deemed inadequate in terms of hair longevity. It was seen that 90.24% of patients
with 0.43 ratio and 94.92% of patients with 0.53 ratio did not have any noteworthy
reduction of transplanted hair.
Table 1
Outcome
|
Patients with 0.43
|
Patients with 0.53
|
|
No noteworthy hair loss (< 10%)
|
37
|
56
|
|
Noteworthy hair loss (> 10%)
|
4
|
3
|
|
Percentage (%)
|
90.24
|
94.92
|
Note: Average percentage = 92.5%. Noteworthy hair loss: reduction greater than 10%
of total number transplanted, results deemed inadequate in terms of hair longevity.
Therefore, overall 92.58% of patients recruited in the study did not have any noteworthy
loss of transplanted hair.
The patients themselves reported that the transplanted hair were thicker than the
existing ones.
Discussion
The androgen-sensitive miniaturization of the hair follicles is a pathognomonic symptom
of hair loss, dihydrotestosterone (DHT) binds to specific androgen receptors resulting
in changes in the hair follicles eventually resulting in hair loss.[5]
DHT can stimulate the growth of the hair follicles on the face, chest, and genital
area, while inhibiting the growth of hair in the skin of the scalp. The safe area
of the scalp is anticipated to have no invasion of alopecia even in high grades of
hair loss, as this area is resistant to the effects of DHT.[5]
This is the basis of selecting this area for harvesting the hair grafts.
Various descriptions of safe zone are present.
Unger's[6] definition was in accordance with the facts that the global mean life expectancy
was ≤ 80 years and > 80% of men aged between 70 and 79 years manifested baldness that
is less than Norwood type VII. Unger described the dimensions of the permanent zone
as a line drawn upwards from tragus and another line 2 cm above the auricle which
intersects with the occipital midline. The zone is 7 cm inferior from here.[7]
Cole and Devroye[8] defined the total permanent donor area as 203 cm2, which ranges 62 to 66 mm in the occipital region.
Bernstein and Rassman[9] reported that the safe donor area accounted for approximately 25% of the entire
scalp present in the occipital region. Rassman and Carson[10] described three significant boundaries, anterior boundary, vertically superior to
that of the external acoustic meatus, superiorly 2 cm above the upper border of the
helical rim of the horizontal plane, and inferior border of the donor area is slightly
controversial as it may move upward with the passage of time.
The most crucial and clinically critical standard for determining a safe donor area
is the superior border, which is profoundly related to the maximum extent of vertex
alopecia.[11] It is suggested to leave an area of 1 cm2 under the line of miniaturization to avoid DHT-sensitive hair.
Also, there is no universally acceptable definition for the safe donor zone.[12]
[13]
Occipital scalp has been used as the donor area, the hairs here are naturally androgen
resistant and hence thought to be permanent.[14]
Hence, it is prudent that the hair absolutely be harvested from the exact permanent
zone to achieve long-lasting results.
The area calculated from the ratio method was well within the estimated donor zone.
As it took into account the dimensions of the patient's head, and the fear of accidentally
taking DHT-sensitive hair was minimal.
On examination of the results at the end of 10 months, all transplanted hair were
found to be growing well. For confirmation the density was checked in two separate
1 × 1 cm2 areas.
Note that 90.24% of patients in whom 0.43 was used had no noteworthy hair loss; similarly,
94.92% patients retained the transplanted hair when 0.53 was used.
Overall, 92.58% patients had positive results. This showed that the transplanted hair
were harvested from the permanent zone and estimation of permanent zone using the
ratio method was correct.
Therefore, in our study we were able to establish that the calculated area was fully
within the permanent donor zone and the hair can be harvested safely without the fear
of future loss.
Conclusion
The authors suggest the use of this ratio method to determine the dimensions of the
permanent zone especially in patients with early grades of hair loss as per the Norwood
scale. It is a simple, effective, and easily applicable concept that can ensure long-lasting
results in patients undergoing hair transplants.
