What should I do with my arm which was skin grafted 20 years ago (the scars are visible)? (Photo)

20 years ago i got accidentally burnt by boiling tea on my upper arm. I was kept in hospital for a month during which they took the skin from my left thigh and grafted it on my arm. I guess it did not go as right as it should have, as i was little and sometimes bent the arm when i was not supposed to. I am attaching pictures. I need to know exactly how to minimize these scars. What type of surgery is required? Cosmetic or what?

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