If the damage goes around the entire trunk, then there's really no way to save the tree except through complicated bridge grafting (occasionally done by professional arborists on high-value trees). I had the same thing happen to my newly planted crabapple this winter.
In the future, wrap thin-barked trees in late fall with tree wrap, tinfoil, burlap, or white plastic coil for the winter. There are also some repellents on the market, but you must reapply once a month.
Luke Miller, editor
Garden Ideas & Outdoor Living magazine