(co-authored by Dr. Dayna Smordin – presented here in modified form)

What is first carpometacarpal (thumb)joint arthritis?

The carpometacarpal (CMC) joint is a joint between the metacarpal bone of the thumb and the trapezium bone of the wrist. The CMC joint is often called the basal joint of the thumb. This is the joint at the base of the thumb where the thumb meets the wrist.

Arthritis occurs when the cartilage at the ends of connecting bones wears away. Bones meet to form joints that allow movement of the skeleton. Normally, cartilage acts like a cushion between bones, letting them slide

against each other smoothly during movement. When the cartilage wears away, the cushion is lost and the bones rub against each other causing damage and pain. This can lead to new bone growth that you may see as lumps or changes in shape and appearance.

We often hear about arthritis in the hips and knees, but one common area where arthritis may develop is at the CMC joint. Arthritis at this joint may present as pain or swelling at the base of the thumb, and can lead to decreases in strength and range of motion of this joint. This, in turn, can affect day-to-day activities that require pinching and grasping such as opening jars or turning handles.

What causes CMC arthritis?

Arthritis is commonly a result of aging and use. A lifetime of gripping activities with the thumb opposing the four fingers results in wear and tear of the joint. Other causes can include a previous injury or trauma to the thumb. Arthritis at this joint is more common in females.

Investigations that may be done:

Often plain X-rays can show signs of CMC arthritis. On a plain X-ray, we can see worn cartilage and loss of the space that is normally present between the bones of the joint. We can also see new bone growth which is referred to as bone spurs or osteophytes that result from the bones rubbing against each other.

Activity modifications to lessen pain:

A key component of management is avoiding or modifying activities that aggravate your pain. Pain is often worse with sustained gripping between the thumb and index finger, such as holding a key or a pen, and with tight grips such as used when opening a jar.

You should try to avoid tight pinching. You may also consider using adaptive equipment to help with these daily tasks. There are many different options for these. A few examples are displayed below. You may also avoid these types of activities by using electronic appliances, for instance an electric can opener. Other activities to avoid include carrying, lifting and using heavy objects, and instead using lightweight cookware and utensils. By making these adjustments and using some of the modalities listed below, you can see improvement in grip strength and in pain control.

Modalities:

There are certain things you can do to help with mobility and pain control. This includes the use of heat and cold. Placing ice over the affected joint for 5 – 15 minutes several times a day can help bring down swelling and relieve pain. This can be tried if the joint is warm and swollen. Stiff, achy joints often respond better to heat.

Joint protection is a key management concept. The principles of joint protection include:

• Listen to your body and respect pain
• Avoid activities that cause pain
• Use appropriate assistive devices (see some listed above)
• Use the largest and strongest joints and muscles to perform activities
• Avoid staying in one position for extended periods
• Find a balance of activity and resting

Braces/splints:

A splint may be useful to support and limit movement at the CMC joint. Splints can help decrease pain, encourage proper positioning of the joint during activities and rest the joint. A splint may be worn only at night or during the day with pain provoking activities. Your healthcare team can help you decide if a splint is right for you and the type of splint that will be most beneficial for your individual needs.

Stretches and strengthening exercises:

Exercises can help relieve symptoms and possibly may slow progression of the arthritis. They can help decrease stiffness and maintain range of motion of the joint. It is recommended to perform the exercises twice daily. Always listen to your own body and move within a comfortable range. If the exercises are too uncomfortable or too difficult, review them again to ensure you are performing them correctly, decrease the number of repetitions, and as always, you may contact your healthcare provider for assistance.

There are different exercises that can be tried to improve pain from thumb base osteoarthritis. They are mostly exercises to improve the strength and endurance of muscles that support and move the thumb. Learning these exercises is usually best through a specialized hand therapist. Click here for a link to some exercises for thumb arthritis.

Medications:

Some topical (applied to the skin) medications may help with symptom management. These include capsaicin or diclofenac. Your healthcare provider may recommend applying these directly to the skin over the joint for pain relief. These can often be used as needed. Topical anti-inflammatories like diclofenac cream can be applied up to 4 times per day on a regular basis. They do not act rapidly, but regular application can provide pain relief. They are available over the counter or with stronger strength prescribed by you physician.

Other over-the-counter pain medications may be helpful, such as acetaminophen (Tylenol), ibuprofen (Advil) and naproxen (Aleve). It is recommended to discuss the use of these medications with your healthcare provider.

There are also some options for prescribed pain relievers.

Injections:

Another management option for symptom control includes injecting a corticosteroid into the affected joint. This is often not considered until splints and other pain reliever medications are tried. A long-acting corticosteroid injection can decrease inflammation and provide pain relief. However, the effect is usually temporary lasting 3-6 months, requiring repeated injections. These can be performed by your physiatrist.

When might surgery be an option?

For severe cases, where there has been poor response to other treatments or if thumb mobility is severely limited, surgical options may be considered. The most commonly done procedure is a trapeziectomy and ligament reconstruction. This is where the trapezium bone of the wrist is removed. This is one of the bones in the CMC joint. The ligaments and tendons are then reconstructed and repositioned. Another option is to perform an arthrodesis or joint fusion. This is where the bones of the CMC joint are permanently attached or fused together. This removes the ability to move the CMC joint, but allows weight bearing without pain. After a surgical procedure, you would likely be in a cast or splint over the thumb and wrist for up to 6 weeks. You may then require therapy to help regain movement and strength in your hand.