CFRA is a lot like rheumatoid arthritis, as Jessi mentioned. Some signs of CFRA vs other things that can cause arthritis. (Medication, age, etc)
*Pain comes in spells or episodes, not a daily thing. The episodes usually last anywhere from 12 hours to one week.
* Onset is generally at a younger age, between 10 and 15
* Fever is generally associated with the episodes, and sometimes a rash.
* is relatively rare, affecting only 2-8% of adult Cf patients
* Large joints are most commonly affected, with the knees seeming to be most common, as well as ankles, wrists, hips, shoulders, and elbows. Ry got it badly in his back, though that doesn't seem to be terribly common.
I hope this helps some.