I was thinking along the lines of injury causes inflammation and perhaps blocks the nerves rendering them inoperative Bonzie. Yes you would be able to feel hot foot or knee joints, but not hip injuries. Should improve in a few days or perhaps a week if it's going to.
We had a bantam leghorn go off his feet for no reason at all and it didn't resolve, but at no time did his toes curl. If you watch chickens walk you usually see them curl their toes as they lift the foot and move forwards. Sensible really as it is far less likely to snag a toe. So I think a curled toe is one in a relaxed position, that is one that isn't being controlled.
Hope he gets better. You could try Metacam (anti-inflammatory) from your vet- it's cheap enough unless they want a consultation fee.