The definition of arthritis is inflammation of a joint or joints. It is useful to distinguish the different categories of arthritis as well as the treatments that exist.
1) Osteoarthritis (OA) – this is the run of the mill form of arthritis that can be thought of as resulting from the wear and tear of old age. Cartilage wears away on the bony surfaces of weight bearing joints resulting in the all too familiar symptoms: pain and stiffness, esp. with prolonged physical activity. Knees, hips, and the vertebral column are the main weight bearing joints of the body affected by osteoarthritis. Over 90% of people will have symptomatic OA by age 75.
Treatments for OA include analgesics, esp. NSAID painkillers like aspirin, injections of cartilage components like glucosamine and chondroitin sulfate, and surgical intervention such as knee and hip replacements.
2) Rheumatoid arthriitis (RA) – although the specific cause is unknown, the consensus is that RA is an autoimmune disease. Approximately 1% of the general population suffers from RA; the incidence is believed to be highest in women ages 20-40. The hallmark of RA is pain and stiffness in the smaller joints, esp. hands, wrists, and ankles, that is worse in the morning and subsides over the span of an hour or so. For no clear reason, the DIP joints (distal interphalangeal joints closest to the fingertips) are seldom if ever affected in RA.
The treatment strategy in RA attempts to halt the immune onslaught and prevent irreversible joint erosions. Steroids like cortisone are used to control acute flare ups of RA. Older treatments for refractory RA included immune suppressant drugs like methotrexate and gold salts, but due to their dangerous side effects (bone marrow suppression, kidney damage) they are used as drugs of last resort today. More recently, mononclonal antibody drugs like Etanercept, which binds to and neutralizes the inflammatory cytokine TNFa (Tumor Necrosis Factor alpha), have come into widespread use. Monoclonal antibodies have become the standard treatment for juvenile rheumatoid arthritis (JRA) as well.
3) Psoriatic arthritis – as the name suggests, this form of arthritis accompanies the skin disease psoriasis. Arthritis may also occur in the context of other autoimmune diseases including lupus and Crohn’s disease.
Treatment is mainly aimed at pain relief. If the underlying disease is brought under control, the arthritis often subsides.
4) Infectious arthritis – the main disease that falls into this category is an untreated strep infection resulting in rheumatic fever. Another cause of infectious arthritis is untreated gonorrhea (Reiter’s syndrome) that can affect one or more joints.
Treatment: a course of antibiotics to eradicate the bacterial infection.