&OA of the Carpometacarpal Joint=Degenerative arthritis (osteoarthritis) of the thumb carpo-metacarpal joint (CMC) is a common problem, which usually affects women beginning around the fifth decade of life. People with arthritis of the thumb typically complain of pain or an aching feeling at the base of the thumb.  These symptoms may be aggravated by the weather, grasping, pinching or when severe may be present at rest or at night. Other symptoms include weakness, clumsiness or deformity of the thumb.