A hair transplant, as the name suggests, involves taking hair from one region of the scalp where hair is in abundance and replanting it in another area where growth is sparse. However, it is not individual hairs which are relocated but small groupings of 1-4 hairs called “follicular units”.
To determine the number of follicular units to be transplanted, the doctor measures the bald/thinning area and transplants about 35 follicular units into each square cm. The greater the contrast between the scalp color and hair color the more grafts are needed. Doctors may recommend that patients have one grafting session then wait about a year before deciding if they would like more. Healing time is about 7 days.
Surgeons generally limit the number of grafts per session to somewhere between 1200 and 2500 grafts, depending on how many are needed by the individual patient (the average cost is around 4 to 6 USD per follicular unit or graft). There is some debate between those who favour larger sessions, with up to 3,000 grafts, and staggered restoration where the number of grafts per session is low but the number of sessions is higher. There are arguments for both sides but keep in mind that your body needs time to heal and it may be unwise to demand more grafts per session than the doctor recommends.
The doctor will first make sure that the hair is trimmed short in the donor area then use a local anesthesia both there and in the recipient area. Most doctors prepare the recipient sites with customized blades that match each follicular unit, these blades ranging in size from 0.75mm to 1.3mm (no one is punching holes anymore, unless it is to do a scalp biopsy). A team of technicians will dissect the donor strip using either microscopes or high definition cameras and monitors. Next, the follicles from the donor strip are inserted into the recipient site. Most doctors use a trichophytic closure technique that virtually eliminates scarring (it actually allow hair to grow through the donor scar).
The entire process is complex and not without bodily stress. There is a limit to the anesthetic that can be injected into your system as well as the number of grafts that can be cut. The procedure is also demanding for the physician; while cutting the graft the doctor will keep injecting saline solution into your scalp so that proper skin strength is maintained. He or she also has to be very careful when replanting the hair to make sure it grows in the right direction.