Osteoarthritis and rheumatoid arthritis occur with pain and inflammation of the joints. The principal causes of osteoarthritis are: nutritional and metabolic deficiencies, damage to the articulation or an infection, as well as oxidation from free radicals and genetic problems. Rheumatoid arthritis has other causes, for example, a negative reaction of the immune system (autoimmune reaction). Another cause may be a virus like the flu that is embedded in the joint tissues causing damage, inflammation and pain