Welcome and thanks for posting your query to HCM.
As per your query you have second degree burn over foot. You have not mentioned the exact area of burn wound (meaning the size of the wound). There are certain areas of body which have less blood supply so are either difficult or slow to heal. The top of the foot is also the same kind of area which along with slow healing is also prone for secondary infection. You are correct in your researching that skin grafting
is done generally on 3rd degree burn but mind it “generally/ usually” are not the case in everybody and every site. We have to go for transplantation
of skin where we see late healing or difficult healing area. Generally wounds of all kind heal 1 cm in 10 n-15 days of period, so it is a clinician’s decision rather than a simple thing if your wound is not healing beyond 21 days. Also you have to understand, as I already said, if the area is not taken care properly it can get infected and can go into non healing ulcer stage. So it is better to consult either the same center or any good plastic surgeon who can guide you the best for the problem.
With best health wishes,
Dr Sanjay K Kanodia
MD ( Dermatology and STD/ Venereology)