It's... Star Wars...
But, anyways, in Attack of the Clones, Anakin loses his arm in a duel with Count Dooku, so he replaced it with a robotic prosthetic. In Revenge of the Sith, he loses both his arms and a leg to Obi-Wan in their duel on Mustafar. Later, in Return of the Jedi, he loses another hand in a duel with his son Luke.
