i would probably say you ming have to have general anesthetic as movements elsewhere in your body could cause your arm to move during the operation, but then again if they feel it safe to use local anasthetic then they will probably use that. and best of luck with the operation.
wellp, its not a major operation is it??? after 1 month from the operation you'll be fine and theres nothing much to be worried a bout tomorrow. Just think of it as normal procedure.