Do the prayers that were performed with tayammum during an illness have to be repeated if it was possible to wash some of the limbs for wudu, and how can their number be determined?

Scholars have differed concerning one who is able to wash some parts of the body for purification but is unable to wash the rest. The Shafi'is and Hanbalis are of the view that it is obligatory to wash what one is able to wash and to perform tayammum for the parts that one is unable to wash. This opinion is the most preponderant. Whereas Abu Hanifa and Malik hold that if the greater part of the body is sound, then ghusl is obligatory without tayammum, and if the greater part is injured, then tayammum is obligatory without ghusl. The preponderant opinion is supported by the narration of Jabir concerning the man who suffered a head injury and had a wet dream. The Prophet, peace and blessings be upon him, commanded him to perform tayammum, bind his wound, wipe over it, and then wash the rest of his body. Therefore, the questioner's action aligned with the madhhab of the Hanafis and Malikis, and nothing is binding upon him after the act has occurred. However, it is prudent and good to repeat those prayers to clear one's conscience with certainty, while striving to determine the most probable number of prayers and making them up.