How should a person who has bandage, cast, or wound on his body or a limb perform ablution?
If washing an organ that is broken or wounded harms the wound or set back its recovery, one may wipe over the cast and bandage applied for treatment or the cotton tied with something, in ablution and ghusl. The validity of masah over bandage is confirmed with the sunnah. Ali (ra) said, “One of my ankles was broken. I asked the Prophet (saw) and he commanded that I should apply masah over the bandages.” (Ibn Majah, Taharah, 134)
When one has bandages in any part of body due to broken or displaced bones or wounds, these bandages are opened, organs are washed, and the place of wound is wiped over while performing ablution or ghusl if that does not give harm to the wound. However, in the event that it is harmful to open the bandage, one may just wipe over the bandage without opening it.
It is enough to apply masah over bandage once. That limb becomes ritually cleaned when tthe bandage is wiped. The fact that the limb was bandaged when a person was not in the state of ablution or was in the state of janabah does not prevent the validity of masah. Applying masah over bandage does not have a certain validity period; one may wipe over the same bandage until the broken bone or the wound recovers. If masah would be harmful for health, too, one may omit it as well (Kasani, Bada’i, I, 13-14).
In the event that bandage is changed or drops after applying masah over it, the masah is not invalidated nor is it required to be re-performed. However, when the wound recovers, masah becomes invalid whether or not the bandage is opened.
If bandage or cast covers most of limbs of minor or major ablution, one performs tayammum instead of ablution (Ibn Abidin, Radd al-Muhtar, I, 217, 434, 470 ff.). The verse “And if you are in a state of janabah, then purify yourselves. But if you are ill or on a journey or one of you comes from the place of relieving himself or you have contacted women and do not find water, then seek clean earth and wipe over your faces and hands with it.” (Ma’idah, 5/6) indicates that one may perform tayammum in such situations.
Source: Presidency Of Religious Affairs The Turkey, High Board of Religious Affairs FATWAS