Women have higher amounts of certain hormones that are linked with joint laxity (looseness). Women are three time more likely than men to develop arthritis of the CMC joint. Damage has occurred well before the pain begins. Eventually, the joint is no longer able to compensate for the increasing damage, and it begins to hurt. Since articular cartilage cannot heal itself very well, the damage adds up. Over many years this imbalance in the joint mechanics can lead to damage on the articular surface. If the mechanism is out of balance, it tends to wear out faster.
This is similar to any mechanical device or machinery. When an injury results in a change in the way the joint moves, the injury may increase the forces on the articular cartilage surfaces. This is also true when the ligaments around the CMC joint are damaged by a sprain. After a fracture of the thumb metacarpal, the bone fragments may heal in slightly different positions. An injury to the CMC joint of the thumb, even if it does not injure the articular cartilage directly, can alter how the joint works. Injury to a joint, such as a bad sprain or fracture, can cause damage to the articular cartilage. Doctors sometimes also describe this same condition as degenerative arthrosis. Degenerative arthritis is a condition in which a joint wears out, usually slowly over a period of many years. Related Document: A Patient’s Guide to Hand Anatomy CausesĪrthritis is a condition in which a joint becomes inflamed (red, swollen, hot, and painful). They put the thumb in positions that allow optimal function for thumb-pinch activities. These muscles coordinate together to create a balance of stability. There are also nine muscles that provide dynamic stabilization of the CMC joint. These ligaments can be injured, such as when you sprain your thumb. This function is called ligamentous restraint. The ligaments allow for motion but keep the joint from sliding too far and prevent thumb dislocation. Several strong, thick ligaments hold the CMC joint together. The CMC joint is sometimes referred to as a universal joint because of the wide range of movements possible. The CMC is the joint that allows you to move your thumb into your palm, a motion called opposition. This joint is sometimes referred to as the basal joint of the thumb. The CMC joint (an abbreviation for carpometacarpal joint) of the thumb is where the metacarpal bone of the thumb attaches to the trapezium bone of the wrist. Where is the CMC joint, and what does it do? This can lead to painful osteoarthritis of this joint, thumb arthritis, that may require surgical treatment as the arthritis progresses. This joint is designed to give the thumb its rather large range of motion, but the tradeoff is that the joint suffers a lot of stress over the years. When you stop to think about how much you use your thumbs, it’s easy to see why the joint where the thumb attaches to the hand can suffer from wear and tear. A Patient’s Guide to Arthritis of the Thumb Introduction