THUMB BASE ARTHRITIS
The thumb base is a common joint to be affected by arthritis. The joint experiences significant stress with any activity that requires pinching or grip. Any deterioration of the joint can lead to pain, swelling and weakness of the thumb.
The two main bones that comprise the thumb base are the thumb metacarpal bone and the small bone that it sits on called the trapezium. The joint between these two bones is known at the carpometacarpal or CMC joint. Normally, the two surfaces where the bones meet are covered with a special tissue called articular cartilage. The cartilage allows the two bones to touch and glide on each other with minimal friction during movement and pinch. In osteoarthritis, the most common type of arthritis affecting the thumb base, the cartilage degenerates over time. Ultimately, the underlying bone is exposed and direct bone to bone contact occurs with activity. Since the bones are no longer smooth and cushioned, pain and inflammation result. People will often notice that their joint has become enlarged, warm and tender. There is often achiness with rest and episodes of sharp pain with pinch and grasp.
For mild cases, where the pain is only with activity and the discomfort is tolerable, simple rest, icing and anti-inflammatory medications may be enough to get a flare up to settle down. Joint specific dietary supplements (e.g. chondroitin and glucosamine) might be slightly better than placebo for pain relief, but have not been proven to rebuild or restore damaged cartilage. In more persistent cases, bracing of the thumb base may be helpful. Off-the-shelf braces are available at your local pharmacy, but a brace fabricated or fitted by a Hand Therapist may provide a better fit with less bulk and restriction.
When non-invasive measures are not effective, a steroid (cortisone) injection can be quite helpful. A small injection of medication into the CMC joint can quickly get a flare up to calm down, often for months at a time. Steroid injections do not cure the underlying arthritis, but can often allow people to manage their discomfort and continue to lead active lifestyles.
When conservative measures are not effective, surgical reconstruction of the thumb base may be considered. Unlike the hip and knee, arthritis surgery for the thumb base does not usually involve the use of artificial implants. During surgery, the arthritic section of the joint (usually the trapezium) is removed and the joint is stabilized using neighboring soft tissues (often the flexor carpi radialis tendon). The surgery is typically done as an outpatient procedure.