When you prune in this way a ring of callus will from which is MERISTEMATIC and new roots will develop in new positions.  Crushed and damaged woody roots will not follow that order.

New roots will grow from the ring of callus.

Hew Bush - Woody Root pruned properly.

When transplanting a tree it is a good idea to prune woody roots correctly. 

Woody roots do not have branch collars so the targets are not the same as when pruning the stem.  With sharp tools, woody roots that are damaged, should be pruned straight across like the end of a straw.

Note, we have had problems when we disturb the root system while there is unlignified new stem growth.  That is as the tree is growing in elongation.  Again timing plays an important roll.