Donor provision is crucial in performing hair restoration procedures and repairing bad hair transplants. It is true that many cosmetic defects created by poor methods can be partially or completely reversed by careful removal and re-implantation of unsightly grafts. However, the main factor that usually prevails in the surgeon from achieving all the goals of patient recovery is the limited supply of donors. The exhaustion of a depleted donor can be the result of wasting hair during a bad hair transplant procedure or due to the patient’s own genetic limitations.
Hair waste due to poor surgical technique, as discussed above, is usually the main cause of depletion of donor stocks. An early sign of signs of hair loss may be transplantation, which seems too thin for the number of grafts used, poor growth identified as gaps in the hairline, or uneven density in areas where the coating should be uniform. The fact that donor hair was wasted could be suggested from the incision of the donor, which was longer than expected, for a certain amount of vaccinations or anomalously low density in the donor area near the donor scar. Unfortunately, it is very difficult to establish an exact underlining after this fact, and by the time the surgeon realizes that he has run out of healthy donor hair, the patient’s damage has been completed.
Since an adequate supply of donors is so important for successful repair, the accuracy of estimating the amount of available hair becomes paramount. When performing a hair transplant procedure on a virgin scalp, the quantitative determination of donor nutrition is fairly straightforward, since the density and weakness of the scalp are relatively homogeneous in the area of donors. However, additional factors arise during repairs. Although there may be enough hair in the donor area, it may not be surgically accessible. Factors that limit available donor hair include:
> Low density of donors
> Fine hair size
> Poor scalp mobility
> Scarring
Low donor density -
The density of donor hair (donor density) can be measured using a simple hand-held device called a densitometer. This tool is invaluable for estimating donor density, follicular unit composition and miniaturization. Patients with high hair density have more hair per follicular unit, instead of follicular units being closer to each other. The reverse is also true. A person with a natural low density of hair will have less hair per follicular unit, but with the same distance between units (i.e., 1 follicular unit / mm2). At very low densities, this rule is less applicable.
Traditional perforation scars, which used the open donor method to collect hair, are a visible marker of the surgery. It is easy to estimate the amount of donor hair used when comparing the area of open donor scars with the remaining virgin donor scalp. However, when assembling the bands, the linear scar gives a small indication of the size of the original, since it reflects only the length of the cut skin, not the width. With this method, the actual amount of tissue removed cannot be easily determined.
A percentage decrease in the density of the follicular unit will give an indication of how much tissue has been removed and, more importantly, how much is left for harvest. In general, the density of a person’s follicular unit may be reduced to about 0.5 units / cm2 before the donor area becomes too thin and no longer need to collect hair. Therefore, if the density of the follicular unit in the area of previous yields of donors measures 0.75 / mm2, approximately half of the potential donor hair and approximately half of the usable hair are used. In the above example, a 12.5% decrease in the density of the follicular unit means that in the previous procedure, 25% of the available donor hair was used in this area.
The value in measuring the size of the follicular unit (hairs / follicular unit) and the density of the follicular unit (follicular units / mm2) is that the former gives the surgeon information about the patient’s initial hair density, and how much hair was used in previous operations even when the patient’s initial hair density was not measured.
Fine hair caliber -
Despite the fact that the transplantation is not affected, the diameter of the hair shaft is an extremely important factor in the volume of the hair and, therefore, the available supply of hair. The diameter of the hair shaft is less frequently mentioned than the actual amount of hair, because it is harder to measure. However, its importance both in the primary transplantation procedure and in the repair of poor hair transplants cannot be overestimated.
The diameter range of the core hair rod is approximately 2.3 times (0.06 mm for very fine Caucasian hair and 0.14 mm for coarse Asian hair). This represents a change in the x-section area about 5.4 times, since the area = ~ r2 or ~ (1 / 2d) 2. In contrast, the density range of hair in patients that we transplant is from 150 hair / cm2 per s low density, up to about 300 hair / cm2 for those who have the highest, the difference is 2 times. If we compare this with the 5.4-fold range of the cross-sectional area of the hair, then we see that, in theory, changes in the shaft diameter of the hair should affect the appearance of fullness (visual density) 2.7 times more than the absolute number of hair,
The importance of this in the repair lies in the fact that with a certain degree of "blocking" thin hair will provide less camouflage than coarser hair. Therefore, thin hair should be transported in larger quantities or in several sessions to achieve the same degree of masking. When this amount of hair is unavailable, trade-offs must be made.
Poor scalp mobility -
The density of the donor and the diameter of the hair shaft are not the only factors affecting the available supply of donations. In order to remove a sufficient amount of hair using the strip method, there must be sufficient weakness of the skin to close the wound after removing the donor strip. In conditions of low donor density, the presence of adequate scalp weakness is especially important because an extended scar can be seen through thin hair.
The location of the donor donor significantly affects the mobility of the scalp. The ideal position for a donor incision is in the middle of the permanent zone, which in most people lies at the level of the external occipital protrusion and the upper occipital line. The muscles of the neck are inserted into the lower part of this ridge, so that the incision below this anatomical reference will be affected by muscle movement, which directly benefits. The stretched scar in this place is extremely difficult to restore, as repeated excavation, even with underlining and multi-layer closure, is usually healed even more widely. To exacerbate the problem, you can most likely cut through the fascia with a low incision of the donor; once the fascia is broken, the risk of increasing the width of the scar increases significantly.
The incisions located much higher than the occipital protrusions, there is a greater growth of dilated scars, but this risk is not as great as if the inclusions were placed below the occipital protrusion. The main risks associated with the placement of scars on the posterior scalp are the lack of permanent hair (it can be susceptible to androgenic alopecia) and the future appearance of the scar if the donor fringe should be further narrowed.
In the “Extraction of follicular units”, a method that uses very small strokes (~ 1 mm) to remove individual follicular units directly from the donor area without using a linear incision can be circumvented by the problem of dense scalp. This procedure is somewhat similar to the old punching technique, except that in addition to simply holding the punches parallel to the hair shafts, the punches are now installed above individual follicular units. When using this procedure for repair, follicular transection can be a significant problem, since the alignment of the follicles is often filtered with a scar tissue.
Scarring -
Scars in the donor area limit the amount of hair available to the surgeon for a number of reasons. The most obvious is that a large donor strip needs to be removed in order to collect the same amount of hair. The second, mentioned above, is that the scars reduce the slack of the scalp by destroying the elastic tissue and destroying the subcutaneous space. This causes the dermis to contact the fascia below. The third is that the scars themselves may be visible and require more hair to be left in the donor area in order to cover the scarred area than is necessary to cover normal scalp.
In order to avoid cutting, but in the face of poor imaging, the surgeon using the traditional punch technique often went completely through the subcutaneous space to make sure that it was below the level of the hair follicle. Since it took a lot of individual strokes, this could lead to a much more erasable subcutaneous space than with a linear incision. The very nature of the secondary healing of the target on which the technical donor depended depended on a significant amount of scars in the donor area.
The presence of open donor scars may give the surgeon a false sense of security, believing that, since the removal with the primary closure was not performed, the patient's donor weakness was not compromised. This logic can lure a careless surgeon into collecting a donor band that is too wide, often with catastrophic consequences. When the surgeon tries to close the donor wound, tight closure requires more stress on the sutures. However, sutures tend to tear off the wounded edges of the wound, since scar tissue is much less elastic and more loose than normal scalp. Attempting to redistribute tension, preventing the risks of causing additional injury to a larger area, and can lead to even more injury.
