Osteoarthritis commonly affects the carpometacarpal joint at the base of your thumb. Symptoms include pain, swelling, and stiffness.

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Osteoarthritis (OA) happens when the tissue that helps cushion a joint breaks down over time. This leads to symptoms such as pain, swelling, and stiffness in the affected joint. As OA worsens, it can become more difficult to do daily activities.

OA affects over 32.5 million adults in the United States. It’s also the most common type of arthritis in older adults.

OA frequently affects the joints of the hand, including the carpometacarpal joint at the base of the thumb.

Keep reading below to learn more about carpometacarpal arthritis, its symptoms, and how it’s diagnosed and treated.

Illustration of carpometacarpal arthritisShare on Pinterest
Carpometacarpal arthritis. Illustration by Jason Hoffman

The carpometacarpal (CMC) joint is found at the base of your thumb. You may also see it referred to as the basal joint of the thumb.

The CMC joint is a saddle-shaped joint that connects the bones of your thumb to your wrist. It’s also the joint that allows your thumb to twist, pinch, and rotate. The mobility of the CMC joint is what allows you to grasp and grip various objects.

When you use your thumb, you put pressure on your CMC joint. In fact, it’s estimated that any force experienced at the tip of your thumb is 13 times stronger at your CMC joint.

Over time, changes can occur in the tissue that supports the CMC joint. Eventually the bones of the joint can start to rub against each other, leading to symptoms of CMC arthritis, such as pain, swelling, and stiffness.

CMC arthritis affects your dominant hand 60–65% of the time. The symptoms of CMC arthritis include:

  • pain that is:
    • localized to the base of your thumb
    • worse when using your thumb, such as when turning a key, opening a jar, or snapping your fingers
    • a dull ache after prolonged use of your thumb
  • swelling at the base of your thumb
  • loss of grip strength
  • reduced range of motion of your thumb
  • deformities at the base of the thumb

Because we use our thumbs for so many different tasks, CMC arthritis can have a significant affect on daily life.

A 2017 review of available literature notes that arthritis of the CMC joint is often reported as the most painful type of arthritis of the hand joints. A 2021 study found that having constant pain and experiencing pain at night were key symptoms of CMC arthritis that affected health.

CMC arthritis develops gradually. Factors such as overuse, injury, and surgery can all contribute to CMC arthritis.

The changes that lead to CMC arthritis start when the ligaments supporting your CMC joint loosen. Over time, this reduced support starts to affect the force applied to the joint, leading the cartilage cushioning it to wear away.

As the cartilage breaks down, the ends of the bones in the CMC joint can begin to rub against each other. This leads to the pain, swelling, and stiffness associated with CMC arthritis.

Some of the risk factors for CMC arthritis are:

  • Age: In general, the risk of OA rises as you get older.
  • Sex: CMC arthritis is more common in females. Research suggests that CMC arthritis is estimated to affect 33% of postmenopausal women.
  • Previous injury or surgery: If you’ve had a previous injury or surgery affecting your CMC joint, you’re more likely to develop CMC arthritis.
  • Family history: If a family member has had OA, you may be more likely to develop it as well.

To diagnose CMC arthritis, your doctor will first review your medical history. They’ll ask about your symptoms, if anything makes them better or worse, and if you’ve had any previous hand injuries or surgeries.

They’ll then examine your thumb using a variety of tests. One of the most common tests is the CMC grind test.

To do the CMC grind test, your doctor will apply pressure to the base of your thumb while rotating your thumb at the same time. Pain or a grinding sound, called crepitus, during this test can signal CMC arthritis.

Hand X-rays can also help your doctor visualize your CMC joint. Using X-ray images, your doctor can look for signs of deterioration and damage at your CMC joint.

Nonsurgical and surgical options are both available for treating CMC arthritis.

Nonsurgical treatment options

Generally speaking, nonsurgical treatments are typically used first for CMC arthritis. This is referred to as conservative treatment and includes:

  • limiting motions that make your symptoms worse
  • adapting movements to help protect your CMC joint, such as:
    • holding objects with two hands instead of one
    • sliding an object toward you instead of lifting it
    • using assistive devices like a jar twister or key turner
  • splinting the joint to support it, reduce its movement, and allow it to rest
  • doing hand exercises to help lower CMC joint stiffness and maintain its range of motion
  • taking medications that reduce pain and inflammation, such as nonsteroidal anti-inflammatory drugs (NSAIDs)
  • receiving a steroid injection into the joint to help lower pain and inflammation

When conservative treatment isn’t effective at managing symptoms, surgery may be recommended. A 2019 study found that self-reported pain and function as well as a change in self-reported pain during conservative treatment was associated with an increased likelihood of having surgery.

Surgical treatment options

Some of the potential surgical options for people with CMC arthritis are:

  • Ligament reconstruction: During ligament reconstruction, a surgeon removes part of the damaged ligament and replaces it with part of a tendon from your wrist.
  • Ligament reconstruction and tendon interposition (LRTI): With LRTI, a surgeon will remove some or all of the wrist bone at the base of your thumb. They will then detach a nearby tendon and pass it through a hole in one of your thumb bones and sew it back onto itself. Then, they will use some of the remaining tendon to reconstruct part of the damaged ligament and place the rest where they removed the bone to provide cushioning.
  • Arthroplasty: Arthroplasty involves replacing the CMC joint with artificial implants.
  • Hematoma and distraction arthroplasty: With this surgery, a surgeon removes the wrist bone at the base of your thumb. Then, they temporarily immobilize your thumb for several weeks, allowing the area to heal.
  • Arthrodesis: Arthrodesis treats CMC arthritis by fusing together the bones in the CMC joint.

Will carpometacarpal arthritis heal completely with treatment?

There’s no cure for CMC arthritis. However, treatment can help manage symptoms and prevent them from worsening.

Each person with CMC arthritis is different. For some, nonsurgical treatments may be effective at reducing symptoms. However, others may only find relief after having surgery.

Your doctor can evaluate the severity of your CMC arthritis and make recommendations on which type of treatment is appropriate for you individually.

Was this helpful?

CMC arthritis is a type of OA that affects the joint at the base of your thumb. Symptoms can include pain, swelling, and stiffness at the base of your thumb. Over time, you can also lose grip strength and develop joint deformities.

A doctor can diagnose CMC arthritis by reviewing your medical history, doing an examination of the CMC joint, and evaluating X-ray images. Treatment of CMC arthritis can be nonsurgical or surgical.

Some people with CMC arthritis may experience relief from nonsurgical treatment options. However, those with more advanced arthritis may need surgery to help ease their symptoms.