I hate blackthorn... a real pain to deal with...
I had to have g/a and surgery to remove a significant lump in my elbow (after ultrasounds, MRI's etc) which turned out to be a caseous necrosis with a thorn in the middle...must have got in my arm lower down and migrated up. At least it justified my private insurance premiums (or I'd still be waiting)
Whatever you put in a hedge make sure it includes fruits and nuts, dwarf trees if necessary.