All perfect praise be to Allaah, The Lord of the worlds. I testify that there is none worthy of worship except Allaah, and that Muhammad, sallallaahu ‘alayhi wa sallam, is His slave and messenger.
His leg does not have the same rulings of the deceased. Rather, it takes the same rulings of the other parts which are cut off. Therefore, it is to be buried so as to respect the human and maintain his dignity. It is not permissible to perform Ghusl for it, offer the funeral prayer over it, or escort it to its burying place or to preserve it until the individual dies so as to bury it with him.
Allaah Knows best.