Always remember Allah(swt) has made our religion easy for us. We are not required to do that which will harm us or is not within our ability. If a medical problem prevents us from doing something we are permitted to do it with out thoughts and intentions. I have a problem that prevents me from doing Salat properly. My legs do not bend as they used to so for salat even at the Masjid, I have to sit in a chair and except for the words, perform Salat in my mind and think of the motions.