31 Jan

Growth Rate of Body Hair Obtained by FUE and the Benefits of Acell

In cases of Androgenic Alopecia, the donor area in the scalp is the best possible source of transplantation hair. However, the donor area in the scalp is sadly limited in everyone, so that alternative sources must be found for donor areas, one of which can be body hair. Sadly, the yields from such sources and the coverage potential of the body hair donor areas are often unpredictable and can produce less than ideal results. It is therefore potentially useful and advisable to identify some means to help improve this survival rate and the coverage value of the body hair donor areas, one of which might be through the application of the extracellular matrix -- Acell.

The yield from a pre treated transplanted beard hair placed in a donor area strip scar which had Acell, to the yield obtained from non pre treated chest hair which was transplanted to a similar scar, were compared to evaluate the comparative yields from the two sources of hair and to test whether Acell offered potential increase in body hair survival rates.

Findings:  The treatment with Acell showed a 92% yield, in six months, in the beard hair placed in the donor area scar and the absence of the Acell treatment resulted in 0% yield in the chest hair placed in the donor area scar in the same time period.

Methodology

All the recipient sites were created with a 1.3 mm solid core needle which was attached to an incision counting device from Cole Instruments. 50 beard hair grafts were obtained using the 0.9 mm punch from Cole Instruments (CI) set at a depth of 2.3 mm on a minimal depth handle. 25 of these beard hair grafts were obtained from the right side of patient’s neck and the other 25 from the left. 6 chest hair grafts were then extracted using the same 0.9 mm punch on a 2.4 mm setting of a CI depth control handle.

The patient had 4 different locations of strip scars, of which the 0.5 cm X 7 cm strip of donor area scar was located in mid-line donor area superior to most of the 4 other strip scars with the 50 beard hair grafts. This large scar was located within Box 1 and Box 5 of my definition of differences in Donor Area Density in Asians versus Caucasians. The strip treated with six grafts of chest hair was the third most superior, measuring 0.4 cm X 3.5 cm located in box 6.

The scar that received the 50 grafts of beard hair was pre-treated with 2 cc of a solution containing ACell in a 1mg/cc density. The Acell was injected into the complete scar layer. The scar that received the 6 grafts of chest hair was not treated.

Results:

Six months later, the growth of the grafts in each scar was evaluated. The growing hairs were counted with a Counting Incision Device with the tip of a Gentian Violet marker attached to it. A mark was made on every hair that was counted, and the CID accurately recorded each of the marks.

The beard hair grafts showed growth in 46 out of the 50 grafts, while the chest hair grafts showed growth in 0 out of the 6 grafts.

Discussion:

Past experience has shown a variety of possible differences in body hair survival rates. Most of the studies were ones where minimal density was attempted, and they suggest that the optimal rate of graft growth is 60% with any type of body hair. On the other hand, scalp hair often yields as much as 90%. In the past, survival rate studies have often been impaired by the absence of accurate means to record the exact number of hairs that have shown growth. The innovative use of the CID which I equipped with the gentian marker to accurately mark and record the hairs, gives a much better count of the hairs that have grown. This can enable the physician to ensure that none of the growing hair was missed or counted twice, ensuring that the count thus recorded is absolutely accurate.

This study clearly shows a difference in the survival rates of beard hair when compared to the survival rate of chest hair. It also shows a difference in survival rates for the grafts placed into the recipient area which was pre-treated with Acell when contrasted with the recipient area that got no Acell. Another informal investigation was performed to evaluate the long term survival of some chest hair grafts that had been placed into a pre-treated strip scar over a year ago. The growth of the chest hair in this ACell treated patient was not at the same high rate as the growth shown by his beard hair as a result of a 2 year old procedure. This prompted me to check if pre-treating scalps with Acell really caused an improvement in chest hair growth. Anecdotal evidence shows that the Acell seems to improve the survival of grafts of chest hair in 6 month follow ups. As a natural follow up of this evaluation, one must objectively evaluate the actual survival rate of grafts of body hair in both the presence and absence of ACell in donor scars.

Strip scars often have no hair at all growing in them, even in cases with trichophytic closure. Without such trichophytic closures, these scars are even more predominately devoid of any hair. Such barren areas help to measure transplant yields. Although these areas are not really normal skin, these strip scars are known to readily accept hair grafts and to produce good yields. Bald areas created due to androgenic alopecia, to the contrary, often contain dormant hairs that can resume growth confusing the hair yield study. These exogen hairs, in this otherwise bald zone, can resume growth during the study duration, before the follow up, confusing the results, and producing a count that is higher than the actual yields. Also existing remaining hairs in an area that is mostly bald can be counted before the study begins, but might later evolve into an exogen phase before evaluation resulting in inaccurate lower yields. Strip scars do not have such issues with exogen hair, making them ideal for analyzing graft hair growth yields.

Using a donor template can help define regions of the patient’s donor area more precisely, and to follow the specific regions to evaluate the hair growth yield. Each of the zones or boxes is predictable according to the 8 major and 6 minor scalp regions. The presence of the scar in any of the boxes is easily annotated before a procedure. Also, any action within a specific box can be recorded while the procedure is ongoing so that the physician can later follow the consequences of the actions, and monitor the density of the follicular units present in any region. It also allows the annotation of skin lesions present before the procedure, which may include removal of prior grafts through FUE or locating any scar.

Prior studies of body hair survival rates have suggested that a 60% yield is good, and that higher densities negatively impact the final yield. On the other hand, lower densities can often result in much better yields. High densities of body hair can sometimes produce high yields, but for this study we did not choose a higher density, not wanting to include this variable in the evaluation.

The final length of the hair growth with the beard hair transplant suggested that most of the grafted beard hairs began their growth at the very beginning, assuming a mean growth rate in the range of 0.4 mm/day, like scalp hair. Most body hair shows growth at the rate of 0.2 mm/day, but this increases to as much as 0.35 mm/day when they are transplantation onto the scalp. It is seen that beard hair grafts grow much faster than most other body hair types. Another advantage of using beard hair for such transplantation is the results are much more cosmetic even when other sources produce similar or even slightly higher rates of yield. The rationale for such an improved coverage lies in the higher diameter of the beard hair shaft, which gives improved volume. As a general rule, double the diameter of hair shafts, and you quadruple the volume of hair because a cylinder of hair has the volume: V = Õ r2 h. also body hair can seem to become finer when it is transplanted to the scalp, but beard hair retains its diameter. Additionally, beard hair grows with a typical wave that enhances the coverage and volume. This makes beard hair grafts ideal for a cosmetic benefit and improved coverage of the scalp compared to other types of body hair. However, remember that in people with straight and fine hair, the added curl of the beard hair graft can produce an unwanted and unacceptable contrast to the existing scalp hair.

Although beard hair generally produces a yield of around 60%, that increased to 92% in this case. The scalp donor area is limited, and so, many patients seek other sources to harvest more hair, sources like body hair. Sadly, many studies seem to suggest that the results are widely variable, making it important to find a means to improve the coverage and the yield from sources of body hair. From this evaluation it appears that the treatment by Acell injection may improve the survival rate of beard hair and significantly improve its survival rate compared to alternative body hair sources that have not been treated with Acell.

This study also suggests that we must study the many benefits of Acell with regard to body hair transplantation, n further depth to see whether it can further improve survival rates in body hair grafts. Ideally the follow up of this study would be one that compares and contrasts survival rates of body hair grafts from the same source into different scalp regions to analyze if Acell can impact it. In this particular brief study, it does appear that Acell has a beneficial effect on survival rates of beard hair.

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