Arthritis is a category of diseases marked by pain and swelling in the joints. In fact, the word "arthritis" means inflammation of the joints. Such pain and swelling can be caused by the wear and tear of osteoarthritis, the autoimmune response of rheumatoid arthritis, or the metabolic dysfunction of gout. Red, swollen bumps near the knuckles and other joints are a common feature of arthritis.

The pain, stiffness and swelling of osteoarthritis occur in joints that have experienced heavy use. These problems can affect large joints, such as the knee, hip or shoulder, or the small joints of the fingers. Stiffness is generally worse with repeated use and better with rest. Heberden nodes are small, red nodules that occur at the last joint of the finger. They may deform the joint, creating the knobby knuckles and twisted fingers of severe OA.

Bouchard nodes are similar to Heberden nodes. These growths are found at the middle joints of the finger, just above the Heberden nodes. While Heberden nodes are found only in OA, Bouchard nodes can be found in both OA and rheumatoid arthritis. These nodes can be very painful or cause no pain at all.

Rheumatoid arthritis is characterized by pain, stiffness and swelling in bilateral wrist and finger joints. It can create significant deformity over time. The pain and stiffness are generally worse at the beginning of the day and improve with gentle movement. Rheumatoid nodules are bumps beneath the skin that occur on the forearms and both sides of the hands. About 25 percent of people with RA have these nodules.

Gout is an extremely painful disease characterized by joint stiffness and swellings known as tophi, felt as small bumps under the skin. Gout can affect any joint, but typically occurs in the big toe. Gout is caused by an excess of uric acid in the blood, usually due to an inability to break down purine, an amino acid found in meat, alcohol and some fish. Uric acid forms crystals, which tend to deposit in the toes and feet. Although gouty tophi commonly appear in the big toe, they are also found in the elbow, fingers and even such unlikely places as the ears and vocal cords.