Osteoarthritis (arthritis) is the most common cause of joint pain in middle-age and older persons. It often occurs in large joints, such as the knees and hips, but it can also occur in the hands. Thumb arthritis is fairly common. Thumb osteoarthritis causes pain at the base of the thumb, which limits movement and function. Treatment of thumb arthritis includes drugs and steroid injections for pain. Some experts recommend splinting. Splinting is inexpensive and safe, but no research has yet shown that it helps persons with thumb arthritis.