ABSTRACT
In addition to beard hair, hair from other body areas can be used in follicular unit excision (FUE). Currently, there are no reports documenting the long-term characteristics and survival of these transplanted grafts, leaving their long-term survival unknown. Therefore, we conducted a long-term study in which this author’s leg hair was transplanted to my frontal scar. Despite a high percentage of leg hairs being in the telogen phase, we observed a high survival rate of transplanted hairs from the lower leg to the scalp scar over an extended time frame. However, we noticed that the recipient site influenced hair caliber, and, after 10 years, all the leg donor hairs had miniaturized, making this procedure less effective. Hence, long-term observation is necessary to evaluate any changes in the characteristics of transplanted leg hairs over time when used for scalp scar transplantation.
- body hair transplantation (BHT)
- follicular unit excision (FUE)
- leg hair
- long-term survival
- recipient dominance
INTRODUCTION
The growth of follicular unit excision (FUE) and advancements in the field of hair transplant surgery have enabled us to use hair from other parts of the body, in addition to scalp hair, as donor hair for patients with androgenetic alopecia (AGA). While body hair, apart from beard hair, may not be suitable for many East Asian patients because of their many fine hairs, they could potentially be used as a source of donor hair for the hairline region and the wound scars caused by hair transplants. The body regions other than the beard and the scalp also have a high-rate telogen phase above 60%,1 but we do not have data on the long-term survival rate and changes in hair diameter after transplanting. Therefore, I decided to transplant my leg hair to the linear scar in my frontal scalp.
MATERIALS AND METHODS
I began this study in 2008 when I was 41 years old. Grafts from my left lower leg were extracted using the two-step method and a 1mm sharp punch. The non-shaven FUE technique was selected and a self-made, modified, suction-assisted Versi handle was used for the manual technique and an automatic system for the mechanical technique (Figure 1).
Non-shaven FUE. A: Modified suction assisted Versi handle; B: OmnigraftTM.
The grafts were stored in chilled saline and 15 one-hair grafts were selected and linearly inserted into the frontal scar in a single row one hour after extraction. The average hair caliber and length of the 15 grafts were 79.6μm (60-100μm) and 22.5mm (12-28mm), respectively. The incisions were made sagittally using a 0.7mm cut-to-size blade (Figure 2).
A: Pre-op photo showing the linear scar on the frontal area; B: after incision; C: post-op photo immediately after transplantation.
Post-operative evaluation was divided into four stages according to hair thickness by trichoscopy: 1) a coarse hair was the same thickness as an original hair; 2) a medium hair was finer than an original hair; 3) a fine hair could be seen with the naked eye; and 4) a miniaturized hair, invisible to the naked eye, was defined as a very fine hair (Figure 3).
Photographic and trichoscopic evaluation method. A: The day after hair transplantation; B: 3 years after hair transplantation; C-1, 2: 15 years after hair transplantation.
The short-term judgment of survivability was done at 3, 4, 5, 6, 7, 9, 12, 13, and 16 months. I also performed a hair count every week from July 2018 to September 2020 to evaluate the hair cycle and true graft survival of the transplanted grafts. Trichoscopy was used to evaluate hair growth.
RESULTS
During observation, I noticed that the transplanted hair became thin in the early post-operative period; I calculated the non-miniaturized (= coarse) hair survival rate at the same time. The short-term post-operative graft survival rates at 3, 6, 9, 12, and 16 months were 93.3%, 66.7%, 80%, 73.3%, and 80%, respectively. The coarse hair survival rates at 3, 6, 9, 12, and 16 months were 60%, 40%, 53.3%, 53.3%, and 33.3%, respectively. At 16 months, the average caliber of eight coarse to medium hairs had decreased by 20μm (average: 59μm) (Figure 4).
Chart showing short-term survivability rates.
When looking at the long-term results, I noticed two tipping points for the survivability: at 2 years and at 10 years. From the second year onwards, the survival rate remained at about 50%, but the number of coarse hairs decreased significantly, and they disappeared after 10 years (Figure 5). The thickness of every transplanted hair was reduced, and the leg hair to scalp scar transplant was not effective at all beyond 10 years post-transplant. However, as leg hairs have a high-rate telogen phase, the graft may survive even when no hair growth is observed. Therefore, I observed weekly for 2 years (110 weeks) from year 10 onwards. The survival rate after 10 years was in the range of 33.3% to 73.3%, with an average of 49.2%. All of the coarse- to medium-hair survival rates during the 2-year weekly observation period were 0%. Assuming that they survived and they grew at once during the same period, since each transplanted hair has its own different hair cycle, we can determine that the graft survival rate was 86.7%. The duration without hair growth also ranged from 1 to 93 weeks; the duration with hair growth ranged from 1 to 36 weeks. These durations varied from graft to graft, and some grafts may have contained more than one follicle.
Chart showing long-term survivability rates.
DISCUSSION
The average follicle survival rate from 3 months through 16 months after transplanting was 80%, and the survivability from the second year on has remained stable at approximately 50%. However, the miniaturization in the grafted hair accelerated after a year, and all hairs changed to finer hair after 10 years and never returned to their original thickness. More surprisingly, they survived at an 86.7% rate. Thus, though leg hairs in this study have an excellent survival rate in the scalp scar even after the lapse of a long period, this procedure was not very effective because of the miniaturization. Important limitations of this study include that it is only a single procedure in a single individual. This case also involved transplanting into scar tissue, which may support lower survival than other types of recipient tissue. It is important to perform additional larger studies that track long-term follow-up.
Hwang reported that the recipient site could influence hair growth rate, hair cycle, and graft survival, though the hair caliber might not change accordingly.2 In this study, all the transplanted leg hairs gradually miniaturized over time, and this detailed observation showed that most survived; however, it was just difficult to see them with the naked eye. The hair follicle cycling also varied from graft to graft, and it varied even within the same graft.
When performing body hair transplantation (BHT), the recipient site influence is likely to vary depending on the type of transplanted hairs and the recipient site. Therefore, long-term frequent observations are required. It has been noted that the survival rate of extremity hair grafts is low and unpredictable,1 so we should at least be prudent in choosing leg hair as a candidate for the donor area.
CONCLUSION
Taking the high-rate telogen phase into consideration, the long-term follicle survival rate of transplanted leg hair into scar was very high in this single case. However, all the leg hairs had miniaturized by 10 years post-transplant, so this procedure was not effective. According to the above results, BHT could be affected by recipient dominance, although there may be ethnic differences.
Larger studies are still needed on long-term survival in BHT, including studies on leg hair into other recipient tissue types. The results of this single case highlight that when transplanting leg hairs into scalp scar, long-term surveillance of greater than two years is required.
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