Ans: Arthritis is caused by your body’s immune system attacking your body tissues. The synovium is a soft tissue in the joints that emit a nourishing fluid that also lubricates your joints. Rheumatoid arthritis is a synovial disease that can destroy a joint. Osteoarthritis is caused by aging or damage to the joint. This is all explained in more detail in paragraphs 2 and 3 of this review – right at the beginning.