The carpals are the small bones of the wrist.  The metacarpals are the long bones of the hand.  They meet at the carpometacarpal, or CMC, joints.  The space where two bones meet is known as a joint.  The ends of the bones are protected in joints by a rubbery cushion capping the bone known as articular cartilage. Osteoarthritis is a condition in which the articular cartilage wears away.  As the cartilage wears away, the bones begin to grind against each other.  This often results in pain, especially with activities that push the arthritic bones against one another.  Osteoarthritis is also known as degenerative joint disease or, simply, arthritis.  The carpometacarpal (CMC) joint of the thumb is one of the most commonly affected joints.  Degenerative changes at the 1st CMC joint are sometimes referred to as CMC arthritis or basal thumb joint arthritis. Why some people get osteoarthritis at an earlier age than others can be a difficult question to answer.  Many people claim that arthritis "runs in the family."  It is likely that genetics is a factor.  Lifestyle can increase the stress placed on the CMC joint and, in theory, may speed up the degeneration of the cartilage at the base of the thumb.  If CMC arthritis of the thumb is suspected, a CMC grind test can be performed.  This is done by applying an axial force to the thumb and grinding the metacarpal against the trapezium (one of the carpal bones).  If this recreates pain, the test is positive and CMC arthritis is likely present.  X-rays can be obtained to confirm the presence of CMC arthritis.  X-rays will demonstrate narrowing of the joint space and osteophyte formation (bone spurs).  Treatment options for CMC arthritis include non-steroidal anti-inflammatory drugs (NSAIDs) such as ibuprofen, bracing, steroid injections, and surgery.  A steroid injection, often referred to as a cortisone shot, can help reduce inflammation and pain.  If non-operative treatment is not effective, surgical options may be considered.  One of the more common surgeries for CMC arthritis is known as ligament reconstruction tendon interposition arthroplasty, or the “anchovy procedure.”  This involves removing the arthritic bone and replacing it with a soft cushion made of tendon. Another available surgery is the thumb carpometacarpal joint arthroplasty.  The arthritic portions of the bones are removed and replaced with metal prostheses.