Recent discoveries show more about the Roman cross.
Four iron spikes were used. One in each wrist. The wrist was considered part of the hand in both the Hebrew and Greek. Then the legs were placed on the outside of the cross and there was spike driven in each heal to connect them to hold them on the cross. These 4 spikes made it impossible for anyone to fall off the cross.
This gives a different picture than what you find in so many of the traditional pictures of Jesus on the cross but it makes more sense.
Since the Jewish laws called for death by stoning the prophecies about Jesus being lifted up could not have been lifted up could not have been fulfilled until the Romans were in control of Jerusalem.