Shabbat 66A

ורבי יוסי אוסר.

And R' Yosei prohibits going out into the public domain with the wooden leg, since he does not consider it to have the legal status of a shoe.

ואם יש לו בית קיבול כתיתין ⁠— טמא.

And if the wooden leg has a receptacle for pads, a concave space at the top of the leg into which pads are placed to cushion the amputated leg, it assumes the status of a wooden vessel and can become ritually impure.

סמוכות שלו טמאין מדרס, ויוצאין בהן בשבת, ונכנסין בהן בעזרה.

And his supports, which are shoes that one who had both of his feet amputated places on his knees in order to walk on his knees, if a zav wears them, they are subject to ritual impurity imparted by treading. A zav is a primary source of ritual impurity. If he touches a vessel it assumes 1st-degree ritual impurity status. However, vessels on which he treads, sits, lies, or leans become primary sources of ritual impurity, provided they are designated for that purpose. These supports are vessels designated for treading. And one may go out with them into the public domain on Shabbat since they have the legal status of shoes. And one may enter the Temple courtyard with them. Although, generally, wearing shoes in the Temple courtyard is prohibited, in this regard, the supports do not have the legal status of shoes.

כסא וסמוכות שלו טמאין מדרס, ואין יוצאין בהן בשבת, ואין נכנסין בהן בעזרה.

However, if one who is crippled to the extent that he cannot walk at all sits on a chair that is attached to him, places supports on his hands, and propels himself along with his hands, his chair and supports are subject to ritual impurity imparted by treading. And one may not go out with them on Shabbat, and one may not enter the Temple courtyard with them.