Arthritis is joint inflammation and commonly occurs at the base of the thumb. The pain associated with arthritis may be from many different sources, including inflammation of the following:
Synovial membrane - A clear, sticky fluid that is released by the synovial membrane and acts as a lubricant for joints and tendons.
Tendons - The tough cords of tissue that connect muscles to bones.
Ligaments - A white, shiny, flexible band of fibrous tissue that binds joints together and connects various bones and cartilage.
Osteoarthritis, a degenerative joint disease, is the most common type of arthritis in older people. It is a slow-progressing disease that primarily affects the hands and the large weight-bearing joints of the body, such as the knees and hips. Osteoarthritis in the hands or hips may run in families, or be caused by injuries, overuse, muscle strain, or fatigue.
Heberden nodes, abnormal enlargements of the bone or cartilage—about the size of a pea or smaller—may occur in the finger joints, and may be aggravated by osteoarthritis.