My experience with ACV is limited to internal and topically on the face for rosacea, but I can't imagine that you could put "too much" on your skin, unless you wind up with peeling skin, etc. As far as I know ACV is exceedingly safe all around, unless you want to put it in your eyes or sinuses undiluted.
Is it even possible to get rid of bone spurs without surgery, though? I mean aren't they composed of bone, after all?