Emperor Palpatine destroys all of Darth Vader’s cybernetic limbs using the Force, then leaves him as he is on the same spot on Mustafar Palpatine found him in years ago. This is a punishment, as well as a test, because Vader let Padme Amidala’s handmaidens escape from him in an act of mercy.
From ā Star Wars: Darth Vader Vol. 1 #6