Posted: 24/01/2015 at 14:31
If the tree is no longer aesthetically pleasing, I would replace it.
But if it grows a good apple you can get it grafted onto a modern rootstock, professionally. Either go to an Apple Day in the Autumn or consult Brogdale where they keep the National Collection. Do you know the variety?
Pansyface, is right, the tree may have been too hard pruned and has been cut back to the rootstock. When it eventually fruits again you will be able to tell by what apples it produces.
5 years is quite a short time for a tree to recover from a traumatic occurrence; give it time.
If you replace the tree, some trees have to be staked throughout their lives if they are on certain rootstocks. Especially the dwarfing ones.