Is it permissible for a patient with rheumatism to prostrate on a small chair or a table designated for prayer when he is unable to prostrate on the ground?

If a worshiper is unable to prostrate, he should gesture for it, making his gesture for prostration lower than his bowing, and he should not raise anything to prostrate upon, due to the saying of the Messenger of Allah, peace and blessings be upon him: "Pray on the ground, if you are able. Otherwise, gesture, and make your prostration lower than your bowing."