Psoriatic arthritis and osteoarthritis

Great question, Linda.  Even we rheumatologists often have trouble distinguishing the two.  Osteoarthritis is thought of as a wearing away of cartilage with aging, which in the long terms can result in need for joint replacement due to chronic pain.  Although there may be a little inflammation in the joints, this is not a big component of the disease.  Psoriatic arthritis, on the other hand, is an inflammatory condition in which the joints become inflamed and damaged as a result of inflammation.  It is usually associated with psoriasis, a scaly skin condition that can range from one or two patches to diffuse involvement of the body.  The treatments for the two conditions are very different, so a correct diagnosis if key.  Usually there is not too much trouble telling the apart, but sometimes because both cause bone spurs, they can look somewhat similar.