Can RA cause rotator cuff damage?

My Mom got backed into by a (hit and run)and panicked trying to get out, resulting in a tear in her shoulder cuff, but she had osteothritis already, so the insurance of the truck driver and co. are hassling her, saying they are not responsible for her disability (time lost from work, etc) because she already had arthritis and that caused the tear. I read on the Net that of all forms of arthritis, it is RA which is most commonly the cause of rotator cuff tears, but I have lost the article. Can you comment? I think they will also try to say that her torn rotator cuff is because she is older (71); however, she had acute pain right away when she tried to pull the door handle open (towards herself as she sat) and then immendiately could not do things such as lift a milk container out of the fridge, run a vacuum cleaner, etc.at home. She needs an answer from a docotr on this matter, and since I am just a newly-graduated colleague, I cannot consider myself much of an expert in the field. Would you help? My email is
campo-marino@tiscali.it. Thank you. Angela Taeschner, M.D.