How can you tell if a graze on your knuckle has become infected? a good amount of skin was taken off and my knuckle is now stiff and painfull.

Skin changes: when you have infection from broken skin there can be redness, swelling, increased pain and sometimes draining pus, sometimes there will be a red streak or line going up your arm which means the infection is spreading. you should have the graze checked to make sure it is healing well and not infected, also anytime you have an open dirty wound you should up date your tetanus shot.