Doctors Jayson and Dixon are both English and this may account for their use of the vague and unscientific term ""rheumatism"" -- which they extend to cover virtually every sort of muscular pain including those caused by tension headaches. There are, say the doctors, more than 100 forms of arthritis, afflicting some 50 million persons in the U.S. alone; fortunately, most clear up with minimal treatment. Jayson and Dixon are helpful when discussing home aids for disabled arthritis victims -- special shoes, cooking and bathing appliances, the value of bed rest and hydrotherapy. They are much less satisfactory when it comes to medication -- a section devoted to new and experimental drugs lists not a one by name. As for the causes, neither they nor anyone else seems to know very much, though current theories point to a systemic infection or a foul-up of the body's immunology system. They clearly don't think much of acupuncture, dismissing it as ""folk medicine."" On the whole Faye Lewis' All Out Against Arthritis (1973) is a better book. A chapter on arthritis as it affects sex, pregnancy and family life (and this is a source of great anxiety for patients) is so cursory as to arouse the suspicion that the authors are embarrassed by the topic. A good layman's introduction to this controversial and little understood disease remains to be written.