I was at my bridge club meeting yesterday listening to all the biddies complaining about their aches and pains. I was surprised by how many of the women have serious thumb problems. It is to the point of pretty extreme pain at the base of the thumb and misshapen thumb joints. I’m only 60 years old (most of these ladies are in their 70s and 80s). Is this from years of playing cards or what?

The base of the thumb (where it joins the wrist) is a common spot for arthritis that can be very disabling. This joint is called the thumb basilar or carpometacarpal joint. Arthritis of the thumb makes it difficult to pick up objects, open doors, turn a key in a lock, get dressed, and many other daily activities we often take for granted. Holding cards for long periods of time can also be compromised by the pain, loss of motion, and weakness.

More than half of all women in their 70s and older will experience this type of problem. Collapse of the basilar thumb joint will cause a zigzag shift throughout the rest of the thumb. As part of the zigzag shift, the metacarpophalangeal (MCP) joint becomes hyperextended. The MCP joint is the large knuckle at the base of your thumb.

Grip and pinch strength are especially affected by this problem. But it doesn’t come just from holding and playing cards. Degenerative arthritis is a condition in which a joint wears out, usually slowly over a period of many years.

Injury to a joint, such as a bad sprain or fracture, can cause damage to the articular cartilage. An injury to any joint of the thumb, even if it does not injure the articular (joint) cartilage directly, can alter how the joint works. These injuries can change the way the joint moves. The injury may increase the forces on the articular cartilage surfaces. This is similar to any mechanical device or machinery. If the mechanism is out of balance, it tends to wear out faster.

Women are three time more likely than men to develop arthritis of the CMC joint. There are several reasons for this. Women have higher amounts of certain hormones that are linked with joint laxity (looseness). There are also some anatomic differences in the joint surfaces between men and women. Increased joint motion from laxity combined with differences in the shape and surface of the bones add to the risk of thumb arthritis in women.

Adults with increased body mass index (BMI) are also at risk for CMC arthritis. There are two possible reasons for this relationship. First, increased mechanical loading seems to occur at the CMC joint in obese adults. This is true even though the thumb is not a weight-bearing joint. Over time, increased load translates into wear and tear on the joint.

Second, patients with a higher body mass index also have elevated levels of lipids (fats), hormones, and insulin-like growth factor around the joint. Local biochemical changes from these hormones may speed up joint degeneration.

The more risk factors present in a single individual, the greater the likelihood of developing arthritis of the thumb, fingers, and hand. Playing cards or other repetitive activities or activities requiring hand grip are just a tiny component in the overall picture.