In Sefer Nishmat Avraham- Orach Chaim Siman 123 The Pardes Yosef offers a number of reasons why it is unnecessary to change the text of a prayer on his behalf. First: It is known that one's soul is considered to have "limbs" corresponding to the physical limbs of the body and, although he has lost one of his physical limbs, all of his spiritual "limbs" are still intact. Second: In spite of his missing a limb, he has not lost the potential to pass on the gene for that limb to his children; it is as if the limb is still contained within him. Finally: The prayer can be considered as referring to the collective body of the Jewish people and it is therefore irrelevant if it does not apply to a particular individual, since it is not directed at him personally, but rather to the nation as a whole.
Chazal teach us that, in contrast to men who have 248 limbs, women have 252 limbs. Because of this the text of the prayer recited for an ill woman was changes to: "and all of her limbs and her 365 sinews" instead of "248 limbs." However, there are many other who disagree, and believe that the text should not be changed since, in terms of halachah, a "limb" is defined as a part of the body which can cause a specific kind of ritual defilement. Since men and women are treated alike with regard to the laws of ritual defilement, only 248 can confer impurity. it is only these 248 limbs, therefore, that are considered significant as limbs, and it is for these limbs that we prater when we recite a prayer for a sick person.