Basal Thumb or CMC Arthritis

What is basal thumb CMC arthritis?

Basal thumb arthritis — also called carpometacarpal arthritis (CMC) — affects the joint at the base of your thumb, where the thumb meets the wrist. This condition is common, especially in women, and can become symptomatic as early as your 30s or 40s. Unlike general arthritis, basal thumb arthritis specifically impacts your ability to grip, pinch and perform everyday hand activities.

At Novant Health, we know how painful, stiff or swollen thumbs can interfere with your daily routines, work and the activities you enjoy. Our orthopedic hand and wrist surgeons specialize in conditions of the thumb and hand and guide you toward treatment options designed specifically to restore hand function and comfort.

Find a specialist

Find a location

Thumb joint anatomy

The thumb CMC joint is a small but complex joint stabilized by ligaments and cushioned by smooth cartilage. Over time, osteoarthritis can cause this cartilage to wear down, leading to bone-on-bone contact, instability and pain.

Because this joint plays a unique role in grip and pinch strength, arthritis here often causes symptoms that are different — and more limiting — than arthritis in other joints.

Overview

Symptoms

Symptoms often include:

Aching pain over the thumb CMC joint (heel of the palm)
Worse with prolonged pinching or gripping (writing, driving)
Cramping of the muscles in the palm
Grinding sensation with use of the thumb
Progressive deformity of the thumb
“Bump” at the base of the thumb in heel of palm
Hyperextension of the middle joint of the thumb (MP joint)

Symptoms may worsen over time if untreated.

Causes

Most cases of carpal tunnel syndrome don’t have one clear cause. Instead, a combination of factors can increase swelling or pressure inside the carpal tunnel, including:

Overuse of repetitive activities
Swelling due to pregnancy
Diabetes, thyroid disease or rheumatoid arthritis
Swelling from fractures or other acute injuries

Diagnosis

Our hand and wrist specialists review your symptoms, medical history and activities, then perform a thorough hands-on exam of your thumb. We explain results clearly so you feel informed and supported.

X-rays often reveal clear signs of arthritis like bone spurs and cysts, though very early cases may not show these changes
If inflammatory arthritis or infection is suspected, we may order additional blood tests or an MRI to pinpoint the cause and guide your care

Why treatment matters

While there’s no cure for basal thumb arthritis, many effective treatments can help manage symptoms and improve daily function. Nonsurgical options often provide meaningful relief, and in some cases, surgery may be recommended.

Nonoperative treatment

Nonoperative treatments for basal thumb arthritis include:

Activity modifications, such as avoiding forceful pinching or prolonged gripping
Anti-inflammatory medications like NSAIDs
Thumb spica bracing for support and stability
Steroid injections to reduce inflammation and pain

Operative treatment

Our hand and wrist specialists may recommend thumb CMC joint reconstruction (CMC arthroplasty), a specialized hand procedure for moderate to severe arthritis when

nonoperative care isn't enough. Advances in thumb reconstruction have made treatment more comfortable and less invasive than in the past. Using specialized implants, our surgeons can address thumb arthritis through a single small incision at the base of the thumb. During the procedure, we remove the arthritic bone and bone spurs and restore stability by rebuilding the ligaments that support the thumb. After surgery, a personalized plan that includes custom bracing and hand therapy helps support healing and guide your return to everyday activities.

Take the next step

Our board-certified specialists are here to help you heal. They can often diagnose the problem in one visit and get you started with a personalized treatment plan. We offer a wide variety of treatment options.