What Is Thumb CMC Arthritis?

The thumb CMC joint, also known as the basal joint or trapeziometacarpal joint, is located where the base of the thumb meets the wrist. This saddle-shaped joint allows the thumb to move in multiple directions, including pinching, gripping, twisting and opposing the fingers.

Thumb CMC arthritis develops when the smooth cartilage covering this joint gradually wears away. As cartilage loss progresses, bone-on-bone contact increases, leading to inflammation, bone spurs, joint instability and pain. Over time, this can result in decreased thumb strength and reduced hand function.

Basal Joint Anatomy

The basal joint connects the thumb metacarpal to the trapezium bone in the wrist. Its unique saddle-shaped structure provides exceptional mobility, allowing the thumb to perform fine motor tasks essential for daily living.

Several strong ligaments including the volar oblique ligament, dorsal radial ligament and ulnar collateral ligament, help stabilize the joint. However, because this joint is both highly mobile and subjected to repetitive stress, it is particularly susceptible to degeneration over time.

Common Symptoms of Thumb Arthritis

Symptoms typically develop gradually and worsen with use. Common signs include:

• Pain or tenderness at the base of the thumb
• Pain with gripping or pinching activities
• Swelling or stiffness in the thumb joint
• Weak grip or pinch strength
• Difficulty opening jars, turning keys or writing
• Grinding or clicking sensation during movement
• A visible bump or deformity at the base of the thumb
• Reduced range of motion

In advanced cases, the base of the thumb may appear enlarged or misaligned. Symptoms often worsen after activity and improve temporarily with rest, but they can significantly interfere with daily activities and quality of life.

What Causes Thumb CMC Arthritis?

Several factors contribute to the development of thumb arthritis, including:

• Age-related wear and tear
• Repetitive thumb use involving gripping or pinching
• Prior thumb or wrist injuries or fractures
• Joint instability or ligament laxity
• Genetic predisposition
• Female sex, particularly after menopause
• Obesity

Over time, these factors accelerate cartilage breakdown within the joint. If left untreated, thumb arthritis can lead to chronic pain, joint deformity and functional limitations.

How Thumb CMC Arthritis Is Diagnosed

Diagnosis typically involves an in-office evaluation by an orthopedic hand specialist and may include:

• Review of symptoms and functional limitations
• Physical examination of thumb strength, motion and tenderness
• Stress maneuvers to reproduce joint pain
• X-rays to confirm cartilage loss, joint narrowing or bone spur formation

Crepitus or a grinding sensation may be felt during movement. Advanced imaging is rarely required unless another condition is suspected. Because thumb arthritis may coexist with carpal tunnel syndrome, evaluation often includes screening for nerve-related symptoms.

Non-Surgical Treatment Options

Non-surgical treatment is often effective in early and moderate stages of thumb arthritis. Options may include:

• Activity modification to reduce thumb strain
• Thumb bracing or splinting for joint support
• Nonsteroidal anti-inflammatory medications (NSAIDs)
• Ice or heat therapy
• Corticosteroid injections to reduce inflammation
• Hand therapy to improve strength and joint stability

Bracing and splints can significantly reduce pain by placing the joint in a supported resting position. Corticosteroid injections may provide temporary relief but are not repeated indefinitely due to diminishing effectiveness and potential side effects.

Surgical Treatment for Thumb CMC Arthritis

Surgery may be recommended when symptoms persist despite conservative care and significantly interfere with daily activities. Surgical options are tailored to arthritis severity, activity level and functional goals and may include:

• Ligament reconstruction and tendon interposition (LRTI)
• Trapeziectomy (removal of the arthritic bone)
• Joint fusion (arthrodesis) for pain relief and stability, with reduced motion
• Joint replacement in select cases
• Thumb osteotomy to redistribute joint forces

All procedures are discussed in detail to balance pain relief, strength, mobility and recovery expectations.

Recovery and Outlook

Recovery depends on the treatment approach:

• Non-surgical care: Many patients improve within weeks
• After surgery: Typically involves several weeks of immobilization followed by structured hand therapy

Most patients achieve significant pain relief and improved function. Early evaluation can help slow disease progression and delay or avoid surgery.

Living With Thumb CMC Arthritis

Long-term management may include:

• Using ergonomic or adaptive tools
• Avoiding repetitive pinching when possible
• Performing prescribed hand exercises
• Applying ice or heat as needed
• Maintaining overall joint health

With proper care, many individuals continue daily activities comfortably and safely.

Expert Thumb Arthritis Care at OrthoTexas

OrthoTexas provides comprehensive care for thumb CMC arthritis, from early diagnosis and conservative management to advanced surgical solutions when needed. Our orthopedic hand specialists focus on restoring comfort, strength and reliable thumb function while tailoring treatment to each patient’s lifestyle and goals.