The joint at the base of thumb allows the thumb to move in a variety of directions and is vital for gripping items in our hands. In normal joints, cartilage covers the ends of bones and acts like a shock absorber allowing smooth, pain-free movement. In osteoarthritis (OA), or “degenerative arthritis” the cartilage layer wears out, resulting in bone-on-bone contact, pain and joint deformity.
One of the most common hand joints to develop OA is the base of the thumb, called the carpal-metacarpal (CMC) or basal joint. The highly specialized saddled-shaped joint is formed by a small wrist bone (trapezium) and the long bone (first metacarpal) of the thumb.
The CMC joint of the thumb is a very mobile joint that allows for a wide range of motion including up, down, and across the palm (opposition), and strength during pinch.
Causes of Arthritis of the Thumb or Carpal-Metacarpal Osteoarthritis (CMC OA)
The exact cause is unknown. Genetics, old injuries such as fracture or dislocation, and/or generalized joint laxity may predispose some people to develop this type of “wear and tear” arthritis.
CMC OA at the base of the thumb occurs more often in women than men, particularly women over the age of 40, but both women and men can have CMC OA.
- Dull, achy or sharp pain or ache at the base of the thumb
- Pain with activities requiring pinching
- Pain may also occur at rest or at night
- Swelling and sensitivity at the thumb’s base
- Joint appears larger than normal
- A bump or bony prominence may develop at the base of the thumb
- The MP joint may bend backward (hyperextend) as it has to compensate for limited motion or pain at the CMC
During the early stages of arthritis, heat and cold can be used 3-4 times a day for 10-15 minute sessions. Heat is typically helpful in reducing stiffness and achy pain, while cold packs may help reduce inflammation and pain. Use whichever makes your hands feel better.
Changing or avoiding symptom provoking activity may help reduce pain. Using different equipment – such as an ergonomic keyboard, tools with a pistol grip, or a key holder – helps reduce stress to the joint.
Over-the-counter creams/ointments/gels may help temporarily decrease pain.
Medication can address symptoms of arthritis, but cannot cure the underlying cartilage and joint damage. Non-steroidal anti-inflammatory may help manage pain and should be used as directed by your provider
Hand Therapists can custom fit splints for the arthritic joint. Intermittent use of a splint is a good long-term strategy to help minimize pain and/or decrease to the CMC joint during daily activities.
While injections cannot cure the underlying arthritis, cortisone injections to the affected portion of the thumb, CMC joint, may help decrease pain. Response to the
injection will vary from person to person and relief is usually temporary.
A variety of surgical procedures can provide long-term pain relief and mobility, when non-operative treatment is no longer an option. Depending on the progression of damage, the surgeon may be able to preserve or reconstruct the joint. Another option is a joint fusion to provide pain relief, but the fused joint no longer can move. A consultation with your hand surgeon can
help decide the best course of treatment for