CMC Arthritis

CMC arthritis is most often caused by the natural aging process. Years of repeated thumb use can slowly wear down the cartilage in the joint. However, several other factors can increase the likelihood of developing this condition.

One major risk factor is gender. Women are more likely than men to develop CMC arthritis, especially after the age of 40. Hormonal differences and joint structure may play a role in this increased risk.

Previous injuries to the thumb or wrist can also contribute. A fracture, sprain, or ligament injury can change how the joint functions, leading to uneven wear over time. Even injuries that seemed minor at the time may increase the risk years later.

Repetitive hand use is another important factor. Jobs or hobbies that involve frequent pinching, gripping, or twisting motions—such as sewing, cooking, or using tools—can place extra stress on the thumb joint.

Genetics may also play a role. If close family members have osteoarthritis, there may be a higher chance of developing it as well. In addition, certain joint conditions, such as loose ligaments or abnormal joint alignment, can make the thumb more vulnerable to cartilage breakdown.

The symptoms of CMC arthritis often develop gradually and may worsen over time. One of the earliest signs is pain at the base of the thumb, especially during activities that involve pinching or gripping. This pain may start as mild discomfort but can become more constant as the condition progresses.

Swelling and tenderness around the joint are also common. The area may feel sore to the touch, and some people notice warmth or slight redness.

As the arthritis advances, the thumb may lose strength. Tasks like opening jars, turning doorknobs, or holding small objects can become difficult. People often find themselves dropping items more frequently or needing to use both hands for activities that once required only one.

Stiffness is another common symptom, particularly in the morning or after periods of inactivity. The thumb may feel less flexible, and movement may be limited.

In more advanced cases, the joint may appear enlarged or misshapen. A bump may form at the base of the thumb due to bone spurs. The thumb may also shift out of its normal position, leading to a noticeable deformity.

Diagnosing CMC arthritis typically begins with a detailed medical history and physical examination. Your Accelerate Orthopedic clinician will ask about symptoms, daily activities, and any past injuries to the hand or wrist. Understanding how the pain affects daily life helps guide the evaluation.

During the physical exam, they will look for swelling, tenderness, and changes in the shape of the joint. They may gently move the thumb in different directions to assess range of motion and identify areas of discomfort.

One common test is the grind test. In this test, the clinician applies gentle pressure while rotating the thumb joint. If this movement causes pain or a grinding sensation, it may indicate arthritis in the CMC joint.

Imaging studies are often used to confirm the diagnosis. X-rays are the most common tool and can show changes in the joint, such as loss of cartilage space, bone spurs, or joint misalignment. These images help determine the severity of the arthritis and guide treatment decisions.

In most cases, additional imaging like MRI is not necessary unless there is concern about other conditions. The combination of symptoms, physical findings, and X-ray results is usually enough to make an accurate diagnosis.
CMC arthritis is a common condition that can have a significant impact on hand function and daily life. It develops when the cartilage in the thumb’s base joint wears down, leading to pain, stiffness, and reduced strength. While aging is the most common cause, factors like repetitive use, prior injury, and genetics can increase the risk. Recognizing the early symptoms and seeking evaluation can help manage the condition more effectively. With proper diagnosis and care, many people are able to reduce discomfort and maintain their ability to perform everyday tasks.