The part of the thumb most likely to develop osteoarthritis is the joint at the base of the thumb, where it joins the wrist, which is called the basal joint or the carpometacarpal (CMC) joint. (A joint is a place where two or more bones meet, in this case metacarpal bone of the thumb and the trapezium bone of the wrist). Your doctor can diagnose this kind of arthritis by evaluating symptoms, which is often the first step.

When a patient says, “It hurts to open a jar or it hurts to turn a door [knob] or I feel like my hand is weak when I’m pinching things,” that’s “classic CMC arthritis,” said Dr. Barr. Other signs can include swelling at the base of the thumb, a bony bump over the joint and limited thumb movement, according to the American Academy of Orthopaedic Surgeons. 

Read the full article at aarp.org.