Do you feel aches and pains specifically at the base of your thumb? Do you find that the pain becomes worse when performing certain types of pinching, grasping, or gripping? Have you been experiencing stiffness, weakness, or a loss of motion at the base of the thumb? If any of these describe your symptoms, you may have osteoarthritis of the thumb, also known as basal joint arthritis or thumb arthritis.
Source: HandCare (ASSH)