CMC Joint Arthritis

The carpometacarpal joint attaches the base of the thumb to the wrist. It is formed from two bones, the metacarpal and trapezium. It allows the hand to grasp objects with a strong grip. People with osteoarthritis of the thumb can experience severe pain, swelling and decreased motion at this joint finding it extremely difficult to do simple activities such as opening and closing the lid of a jar and turning door knobs.

Thumb arthritis, also called basil joint arthritis, may occur due to family history of arthritis, joint injury or overuse of the joint such as in people working on assembly lines. Arthritis of the thumb causes degeneration of the cartilage between the two joint bones, trapezium and metacarpal. In a normal basal joint, cartilage covers the ends of the bones — acting as a cushion and allowing bones to glide smoothly against each other. With thumb arthritis, the cartilage that covers the ends of the bones deteriorates and its smooth surface roughens. The bones then rub against each other, resulting in friction and joint damage. Moreover, the friction between the two bones can also lead to the formation of bone spurs on the articulating surface of the bones restricting further motion of the joint.

Initial treatment of thumb arthritis is aimed at managing the symptoms but does not eliminate the arthritis or repair the joint damage done. Treatment measures include activity modification, splints, non-steroidal anti- inflammatory drugs and corticosteroid injections.

When symptoms get worse a surgical procedure called carpometacarpal arthroplasty may be recommended to reconstruct the damaged joint. The surgical procedure can be done as an outpatient surgery.

In carpometacarpal arthroplasty surgery, the surgeon removes the trapaezium from the joint and replaces it with a ball made of rolled wrist tendon cut from the same wrist. Complications are minimal and may include infection and numbness at the operated site.

After the surgery the thumb is put in a cast for 3-4 weeks and a splint is worn at all times for another 4 weeks. To regain movement and strength of the thumb joint physical therapy is started soon after the removal of the cast. Total recovery time varies and depends on each individual’s healing process. Usually normal activities can be resumed within four months of the surgery.