Hair transplant is a procedure where hair follicles are harvested from a genetically determined abundant permanent hair zone or donor area and implanted into a deficient recipient area. The importance of donor area cannot be downplayed in hair transplant as it forms the first pre requisite of a successful result. The hair transplant donor area in a planned hair transplant is genetically most resistant to hair loss and provides adequate density for harvesting a good crop. Although, based on procedure planned, there can be varied sites from where hair follicle can be harvested, it should be noted that every site has its own peculiar characteristics and need to be assessed for a customized treatment plan.
The goal of donor area evaluation is to evaluate the density of hair, most common hair per follicle ratio, hair shaft diameter to assess thinning, hair texture, scalp quality, scalp laxity and thickness. These assessments give an overview of type of grafts available and what type of method to implement for harvest to give maximum yield and best possible results with least donor site morbidity. It also helps in defining the grafting strategy so as to establish the angle and placement of grafts, density allocation for best results.
Hair in general has 3 primary types. First, the velus hair are fine young hair, intermediate and finally the terminal hair. A follicular unit consists of two to five hair follicles and the usual density ranges from 80 – 120 follicular units per square centimeter. In scalp, follicular density usually is maximum in the centre region of occiput in scalp and reduces laterally. Every harvest contributes to the decrease in follicular density and every time a hair graft harvest causes a reduction in 10 -15% of follicular density. Together with diameter, follicular density has the biggest impact on the cosmetic results of a hair transplant. Hair diameter in its own right, is one of the biggest predictor of coverage possible by the hair transplant. It determines what is the visual perception of density post-transplant. It is essential to have a good hair diameter for better looking results. A person with higher density but thinner hair will not have as good a result relatively as a person with low density but thicker hair.
Another important parameter is the ratio of hair in anagen or growth phase to the hair in telogen or resting phase. Usually the ratio is 90:10 but changes in regions with different growth rate. Anagen or the growth phase is usually the dominant phase while telogen or the resting phase is higher where hair are thinning. Hair in telogen phase are short and club like. Unfortunately, it is impossible to distinguish anagen from telogen hair in donor area with naked eyes and need specialized techniques.
Hair and scalp colour contrast is also another factor which impacts the entire process. Firstly, the starker a contrast ratio is between hair and scalp, the better the apparent coverage. Secondly, white colour hair is difficult both to harvest and graft as it it not spotted easily and therefore difficult to process. On the other side as white colour reflects all wavelengths of colour therefore it does not contribute greatly in providing the ‘covered’ look. Gray hair, on the other hand, can be used for transplant. In people who have wavy or curly hair, it serves to their advantage as it reflects light on different levels and therefore gives a more covered look as compared to people with straight hair.
The ‘Safe’ hair transplant donor area is defined as one that is traditionally used for hair transplant procedures due to its genetic propensity to withstand various factors that cause hair loss. For strip harvesting in FUT, posterior scalp or occipital, sides of scalp or parietal and above ears that is supra–auricular zones are most commonly used. The maximum length of strip that can be harvested at one time is between 25 – 30 cm. sequential strips can be harvested in future but it must be kept in mind that there is a decrease in density and laxity of scalp skin to allow similar quantity of harvest. Therefore, combination of procedures, that is, FUT + FUE serve better as compared to isolated procedures when it comes to higher density requirements. Theoretically, upto half of donor area can be harvested without a noticeable difference in the density but a surgeon needs to evaluate every case individually to assess the best possible option for the patient without donor site compromise.
The harvest process is done under local anesthesia along with what is now popular as ‘vibration’ technique which helps in mitigating the pain while the local anesthesia is given. Once under effect of anesthesia, the surgeon proceeds to harvest the graft in FUT method by incising a strip upto the fatty layer of tissue so as to include the hair roots. The remaining bed is cauterized to stop any signs of bleeding and then closed with a suture in a specialized technique called as tricophytic closure where the emphasis is placed on reducing any kind of bald patch over the donor area and to adequately camouflage the scar line. In FUE, after anesthesia, a punch is either used manually or with micromotor to harvest every follicular unit under magnification. After harvest the donor site is dressed with antibiotic ointment and absorbent dressing which is removed next day. Due to the inherent invasive nature of FUT harvest, the healing time is approximately 2 weeks with stitch removal done around 10th day (if non absorbable sutures are used) whereas in FUE, the area heals by 5th -7th day under normal circumstances. The scarring of donor scar is also different in both the methods. In case of FUT there is a linear scar along the length of incision which, as mentioned above, is designed to be hidden beneath the overgrowing hair. In case of FUE the scarring is pin point stippled and distributed within the remaining density of hair. In both the cases an attempt is made to use the donor area so as to minimize any stigma associated with the hair transplant procedure.
In cases where there is a widening of the scar due to larger strip harvest or in cases where it is less conspicuous due to sparse density, there are options such as scalp micropigmentation to merge the scar into the surrounding tissue by giving an illusion of densely packed follicles and thus hiding the scar.
The donor area recovery time varies from patient to patient. It also depends on the type of hair transplant procedure utilized. On average, it takes 5-7 days for hair transplant donor area recovery to heal after the FUE hair transplant. On the other hand, FUT hair transplant recovery takes a bit longer. Typically, the patient regains his or her usual appearance 10 to 15 days after surgery.
Apart from scalp, there are other donor areas also available in the body which can be used in cases where density is a priority and primary donor area is insufficient or restricted. After scalp, beard is the next preferred site followed by body hair from chest and abdomen. These sites are used preferentially in balding crown and vertex areas to contribute to the density. Their usage is not preferred in case of hairline reconstruction where only scalp hair is used.
Thus, it is essential that a formal consult and clinical examination in person is done so as to avoid any surprises and to formulate a suitable plan based on available donor area options and area needing transplant for a fruitful outcome both for the patient and the surgeon.