‘And so it was in the eleventh year, in the first month, on the seventh day of the month, that the word of Yahweh came to me saying, “Son of man, I have broken the arm of Pharaoh, king of Egypt, and lo, it has not been bound up to apply healing medicines, to put a roller to bind it that it be strong to hold the sword.” '
The attempt by Pharaoh Hophra to raise the siege of Jerusalem, while bringing a short relief, finally failed, and Pharaoh and his army were repulsed. This is described here as the breaking of his arm, and it was broken in such a way that it could not be healed or repaired to enable him to make another attack. He had proved a vain hope. And this was so because Yahweh Himself was against it.