1. Scar alopecia caused by trauma: Generally, after half a year, hair transplantation can be performed only after it is determined that hair follicles at the surgical site have not grown hair.

2. Before the scar hair transplant, you should go to a regular hair transplant hospital for scalp hair follicle examination, and there are enough donor resources. Only when these conditions are met can hair transplant be performed.

3. Blood test is needed before hair transplantation, and good blood supply conditions are the premise to ensure the implementation of scar hair transplantation.