There are more than 100 different types of arthritis ranging from mild forms of tendinitis (eg. 'tennis elbow') to crippling forms, such as rheumatoid arthritis. Also included are gout, fibromyalgia and systemic lupus erythematosus. The most common form is osteoarthritis, the misnamed 'wear and tear' arthritis. It not only affects seniors, but infants and adults as well. The common feature for all these conditions is joint and musculoskeletal pain, which is why they are grouped together as 'arthritis.'