Arthritis is a very familiar word to the majority of the population and often, an easy go to self diagnosis that is happily adopted by many. Osteoarthritis (OA) and Rheumatoid Arthritis (RA) in fact are two common but very different types of arthritis.
OA is also known as the condition of 'wear, tear, and repair' as it's primary cause is a natural breakdown of cartilage and subchondral bone. This is why it is more common in the elderly.
RA on the other hand is a chronic inflammatory autoimmune condition. Meaning that a person is predisposed to the condition for reasons such as genetic factors and blood markers. This means that it can come on much earlier in life.
I have created a couple of diagrams to show the major associated factors with the two conditions to help compare and contrast.