Injury scars are best treated by:

Skin rejuvenation - micro laser peel 

Erbium fractional laser resurfacing

How fractional laser resurfacing is done?

This laser heats tissue to a depth that effectively damages the bad tissue. the area to be treated is prepared by putting topical anesthetic cream.

There is always a improvement in the skin tone and texture after the procedure leading to smoothness of depressed scars.