Tell me about scalp flap surgery/ scalp reduction surgery/scalp tissue expander?

With the advent of micro follicular hair transplant technique, these techniques  nowadays are being considered as of  historical interest. In these techniques the bald area is removed surgically and adjacent hair bearing area is moved using skin laxity. In some cases the hair bearing skin is increased in size by putting tissue expanders (balloons) under it; and this is used to replace the bald areas.

These techniques though considered history, still are useful in select group like–

Localized bad/thin scar over head, where the transplanted hair will not grow due to lack of proper blood supply. In these cases the scar can be excised in one or multiple stages and can be replaced with adjacent hair bearing area giving instant natural results with practically insignificant scarring. This also involves skills of a cosmetic surgeon.