What is the sustainability of a hair transplant?

Transplanted hairs behave like hairs from where it was taken. If the donor hair is healthy, the transplanted hairs will remain healthy.

You have asked a very pertinent question. What is the use of doing a hair transplantation if the hair falls off in a short time after the transplant?
The life of a hair follicle is dictated by the genes and the location from where the hair is coming from. The Hair follicle at the back of the head, in a narrow band extending from one temple to the other, has long life. The rest, falls off as soon as its life is over. If you transplant from this narrow band, then you can be assured that the transplanted hair will behave like the donor area hair. However, if you transplant from an area that does not come from this narrow band, then the hair will fall off as soon as its life is over. This is exactly what must have happened in the cases you saw.

Thank you for asking this question.
Transplanted hair are usually taken from the permanent zone or the donor area; which is the portion exactly between the lines parallel to the top and end of both of the ears at the back of the scalp. The hair roots there are immune to hair loss and so never undergoes the miniaturization of hair process. If the hair is harvested out of this area then these hair might hall as per the progression follows from where it has been taken from. That is why there is a certain limitation towards the number of hair which can be extracted by specific techniques. So it quite a lot depends on the surgeons experience how best the result can be.

Good luck!

Regards, Dr. Amit Gupta