Question: What is the ruling on a prosthetic leg which takes the place of a natural leg?
Answer: “All praise is due to Allah the Lord of the Worlds and may peace and blessings be upon our Prophet Muhammad, his followers, and Companions altogether. I bear witness that there is no God worthy of worship except Allah and that Muhammad is His servant and Messenger. As for what follows:
I think the question is in regards to its permissibility or impermissibility. It is allowed for a person to have a prosthetic leg or hand. There is no harm in it. In terms of washing it during purification and ablution, then it is not necessary that he washes it in ghusl nor ablution” .
Faisal Ibn Abdul Qaadir Ibn Hassan