Thumb Arthritis (CMC Joint Arthritis)

What Is Thumb Arthritis?

Thumb arthritis, also known as basal joint arthritis, occurs at the base of the thumb where the thumb meets the wrist. A joint is formed when two bones meet and articulate, allowing movement. Joints are lined with smooth cartilage that allows bones to glide easily relative to one another. Osteoarthritis, or degenerative arthritis, describes the deterioration of this joint cartilage that occurs with aging and wear over time.

This joint, called the carpometacarpal or CMC joint, is crucial for thumb function. It allows the thumb to move in multiple directions and provides the strength needed for pinching and gripping. As the cartilage wears away, the bones start to rub against each other, causing pain, swelling, and limited motion. Over time, bone spurs may develop, creating an enlarged appearance at the base of the thumb.

Symptoms

Activities that rely on the thumb may result in pain at the base of the thumb, particularly in an arthritic joint. The activities most people notice as painful include pinching, grasping, and gripping. Opening jars, turning keys, writing, buttoning shirts, or using scissors can become difficult and uncomfortable.

Signs and symptoms may include swelling or stiffness at the base of the thumb, pain with use that improves with rest, decreased range of motion, weakness in grip and pinch strength, and an enlarged or bony appearance at the base of the thumb as the arthritis advances. You may notice a grinding sensation when moving the thumb, or hear clicking or popping sounds at the joint.

Causes & Risk Factors

Thumb arthritis typically occurs sometime after age 40. It is more common in women, though men certainly can develop this type of problem. There is a genetic predisposition to developing this arthritis condition, so family history plays a role. Any type of trauma to the thumb can also predispose you to thumb arthritis later in life.

Other conditions such as inflammatory arthritis, including rheumatoid arthritis and lupus, can affect the base of the thumb and cause deterioration of that joint. The exact cause of osteoarthritis in the thumb is not fully understood, but it likely involves a combination of genetics, joint mechanics, prior injuries, and the cumulative stress placed on the joint over decades of use.

Diagnosis

If the pain starts to interfere with your activities of daily living, a visit with a hand surgeon can be helpful. During a physical examination, your surgeon may notice grinding when moving the thumb in certain ways, called the grind test. The joint may be tender to touch, swollen, and have limited range of motion compared to your other thumb.

X-rays are used to confirm the diagnosis and show the extent of cartilage loss and bone changes. The x-rays may show narrowing of the joint space, bone spurs, and changes in the shape of the bones at the base of the thumb. It's worth noting that x-rays show that basal joint arthritis will generally get worse with time, though the rate of progression varies from person to person. Interestingly, even though thumb arthritis will advance with time on x-ray, symptoms do not always get worse, and in some people the symptoms will decrease significantly.

Treatment Options

There is no convincing evidence to support the use of any medications or supplements to prevent the progression of thumb arthritis. Treatment focuses on managing symptoms and maintaining function. Non-surgical options include anti-inflammatory medications (consult your doctor first), use of heat or ice, bracing to support the joint and reduce pain, exercises and stretching, ergonomic adjustments to how you perform tasks, avoidance of activities that worsen symptoms, and steroid injections into the basal joint for temporary relief.

Hand therapy can provide education on joint protection techniques, adaptive equipment, and exercises to maintain motion and strength. Many people find that a combination of these treatments allows them to manage their symptoms effectively for years.

When non-surgical treatment fails and symptoms are significantly affecting quality of life, surgery is an option. Several surgical procedures are available. Surgery can involve removing part or all of the trapezium, one of the small bones that forms the thumb joint, and then cushioning or suspending the thumb joint using various techniques. Fusing the thumb joint is also an option, which eliminates motion at that joint but can provide good pain relief and stability. Your hand surgeon will discuss which procedure is most appropriate based on your specific anatomy, activity level, and goals.

Surgery: What to Expect

Thumb arthritis surgery is typically performed as an outpatient procedure under local anesthesia, with sedation available for select cases if needed. The specific technique depends on the chosen procedure, but most involve removing diseased bone and reconstructing the joint with tendon, implant, or fusion hardware.

After surgery, your thumb will be immobilized in a splint or cast for several weeks to allow healing. The complete recovery after thumb surgery can take anywhere from eight weeks to one year depending on the procedure performed and your individual healing. Early weeks focus on protecting the repair, while later weeks focus on regaining motion and strength.

Recovery

Recovery from thumb arthritis surgery requires patience and commitment to rehabilitation. You'll receive a home exercise program with specific exercises to gradually regain thumb motion and strength. Most people manage recovery well with these home exercises, though hand therapy is often recommended to optimize results and ensure proper healing.

Pain relief is usually very good after surgery, and most people can return to their normal activities once fully healed. Some procedures result in slightly less motion than your original thumb had, while others preserve more motion but may provide less stability. Your surgeon will discuss these trade-offs when helping you choose the best procedure for your needs and lifestyle.

When to See a Specialist

If you're experiencing thumb pain that's interfering with your daily activities, work, or hobbies, it's worth getting evaluated. Early assessment can help identify the problem and guide you toward appropriate treatments. Many people find relief with non-surgical measures, while others eventually choose surgery when conservative treatments no longer provide adequate symptom control.

Dr. Lackey specializes in diagnosing and treating thumb arthritis and can help you understand your options at every stage of the condition. Whether you're just starting to have symptoms or have been managing arthritis for years, an evaluation can provide clarity and a personalized treatment plan.