What Is Osteoarthritis?
Osteoarthritis (OA)is slowly progressive joint disease typically seen in middle-aged to elderly people. The disease occurs when the joint cartilage breaks down often because of mechanical stress or biochemical alterations, causing the bone underneath to fail. OA can occur together with other types of arthritis, such as gout or rheumatoid arthritis.

Symptoms include:
Joint pain and stiffness
Knobby swelling at the joint
Cracking or grinding noise with joint movement
Decreased function of the joint

Who Gets Osteoarthritis?
OA affects people of all races and both sexes.
Most often, it occurs in patients aged 40 and above. 
However, it can occur sooner if you have 
other risk factors (things that raise the risk of getting OA). 

Risk Factors Include:
Older age
Having family members with OA
Joint injury or repetitive use (overuse) of joints
Joint deformity such as unequal leg length, bowlegs or knocked knees

Most often doctors detect OA based on the typical symptoms (described earlier) and on results of the physical exam. In some cases, X-rays or other imaging tests may be useful to tell the extent of disease or to help rule out other joint problems.                                    

 How is Osteoarthritis Treated?
There is no proven treatment yet that can reverse joint damage from OA.  The goal of treatment is to reduce pain and improve function of the affected joints. Most often, this is possible with a mixture of physical measures and drug therapy and, sometimes surgery.  It is always best to get in touch with your physician/ Rheumatologist if you have any of the symptoms listed above.

Source: http://www.rheumatology.org/practice/clinical/patients/diseases_and_conditions/osteOArthritis.asp

Current Osteo-Arthritis Trials: