Arthritis. Artwork of a joint in the thumb affected by arthritis. The area of pain and inflammation is highlighted in orange. The affected joint is between the metacarpal and first phalanx bone of the thumb. There are many types of arthritis. The two most common are rheumatoid arthritis, in which the body's defences start to attack the soft joint tissues, and osteoarthritis, which is generally caused by wear and tear. Both cause pain and joint stiffness in varying degrees. Arthritis commonly affects the joints in the hand, and may lead to disfigurement and loss of grip. Treatment is mainly aimed at reducing symptoms with painkillers and anti-inflammatory drugs.