It really depends on how severe the wound is. On your finger print appointment letter, it clearly states that "If you have open wounds or bandages/casts when you appear, the USCIS may reschedule your appointment if it is determined your injuries will interfere with taking your biometrics".
Just go ahead and immigration officer will determine whether or not you need another appointment. Do not worry too much. Probably your wound is not that bad. If the arch of your finger print is still intact, I think you will be ok.
My 2 cents.