ConditionBones, joints & muscles
Thumb Arthritis (Basal Joint Arthritis)
Thumb arthritis is osteoarthritis of the joint at the base of the thumb, where it meets the wrist, called the carpometacarpal (CMC) or basal joint. The cartilage wears away, causing aching pain at the base of the thumb, especially when pinching, gripping, turning keys or opening jars, along with stiffness, swelling and weakness. It is very common after age 50, particularly in women. Splints, activity changes, exercises and injections help most people; surgery works well when these fail.
Also called: Basal joint arthritis, CMC joint arthritis, thumb base osteoarthritis, carpometacarpal arthritis, trapeziometacarpal arthritis
At a glance
- What it is
- Wear-and-tear arthritis of the joint at the base of the thumb.
- Who gets it
- Adults over 50, especially women after menopause; previous thumb injury and joint laxity add risk.
- Symptoms
- Pain at the thumb base with pinching and gripping, stiffness, swelling, weakness, a bump at the joint.
- Diagnosis
- Examination (grind test) and X-rays.
- Treatment
- Splints, activity changes, hand therapy, pain relief, steroid injections; surgery for severe cases.
- Outlook
- Good symptom control for most; surgery relieves pain in the large majority.
When to get help
See a doctor within a day or two
- A hot, red, very swollen thumb or wrist joint with fever (possible infection or gout)
- Sudden severe pain and deformity after a fall onto the thumb (possible fracture or dislocation)
Book a routine appointment
- Aching at the base of the thumb with pinching, gripping or turning keys lasting more than a few weeks
- Pain that wakes you, or weakness that makes dropping objects common
- A bump or change in the shape of the thumb base
- Numbness or tingling in the thumb, index and middle fingers (possible carpal tunnel syndrome)
- Swelling and stiffness in several finger joints, worse in the morning for over an hour (possible inflammatory arthritis)
Usually safe to manage at home
- Mild thumb ache after heavy hand use that settles with rest and a splint
Why the thumb base wears out
The thumb CMC joint is a saddle-shaped joint between the first metacarpal bone and the trapezium, a small wrist bone. It allows the thumb's wide range of motion, including pinching and grasping, but bears high forces: a strong pinch can multiply forces at the joint many times over. With age, ligaments loosen, the joint shifts slightly and cartilage wears away. Bone spurs form and the joint can partly dislocate, pushing the thumb into a "zigzag" shape.
Risk factors
- age over 50
- female sex (several times more common in women)
- loose joints (joint hypermobility)
- previous thumb fractures or ligament injuries
- repetitive heavy pinching and gripping work
- family history
- inflammatory arthritis such as rheumatoid arthritis, which can also affect this joint
Symptoms
- aching or sharp pain at the base of the thumb, near the wrist
- pain when pinching, gripping, writing, turning keys, opening jars or doorknobs
- stiffness, especially in the morning
- swelling and tenderness at the thumb base
- weakness of pinch and grip, dropping things
- a bony bump at the thumb base
- in advanced cases, the thumb collapsing into a Z shape, with the middle joint bending backward, making it hard to open the hand wide
Conditions that cause similar pain
| Condition | Clues |
|---|---|
| De Quervain's tenosynovitis | Pain along the thumb side of the wrist, worse with thumb movement and lifting babies |
| Carpal tunnel syndrome | Numbness and tingling in the thumb and fingers, often at night |
| Trigger thumb | Catching or locking when bending the thumb |
| Scaphoid fracture | Wrist pain after a fall |
| Gout or infection | Sudden red, hot, swollen joint |
Diagnosis
A doctor examines the hand, pressing on the joint and performing a "grind test": moving and pressing the thumb metacarpal against the trapezium, which reproduces pain and may cause grating. X-rays show narrowing of the joint space, bone spurs and alignment. Blood tests are only needed if inflammatory arthritis is suspected.
Treatment
Non-surgical (first-line)
- Splints: a thumb spica or CMC splint supports the joint, reducing pain; worn at night and during activities that cause pain.
- Activity changes and joint protection: use larger grips, jar openers, key turners, electric can openers and lever door handles; avoid tight pinching.
- Hand therapy: exercises to strengthen the muscles that stabilize the thumb and keep the web space open.
- Heat or cold for comfort.
- Pain relief: topical NSAID gels are recommended for hand osteoarthritis and have fewer side effects than tablets; oral NSAIDs or acetaminophen (paracetamol) at the label dose if safe for you.
- Steroid injections: can relieve pain for weeks to months, most effective in earlier stages.
Surgery
Considered when pain and function remain poor despite several months of non-surgical treatment:
- Trapeziectomy: removing the trapezium bone, often with ligament reconstruction and tendon interposition (LRTI); the most common operation, with good pain relief in most people.
- Joint fusion (arthrodesis): for younger, active people needing strong pinch.
- Joint replacement: an option in selected patients.
- Osteotomy or ligament reconstruction for early disease with loose joints.
Recovery typically involves a cast or splint for 4 to 6 weeks, then hand therapy; full strength may take 6 to 12 months.
Living with thumb arthritis
Most people manage well with splints, adaptive tools and exercises. Pacing heavy hand tasks, using both hands and avoiding sustained pinch help reduce flare-ups.
Frequently asked questions
What are the symptoms of thumb arthritis?
The main symptom is pain at the base of the thumb, especially when pinching, gripping, turning keys or opening jars. Other symptoms include stiffness, swelling, weakness, a bump at the joint and, in advanced cases, a change in thumb shape.
What is the best treatment for thumb arthritis?
Most people start with a thumb splint, joint protection techniques, hand therapy exercises and topical anti-inflammatory gel. Steroid injections help when pain persists. Surgery, usually trapeziectomy, is very effective for severe arthritis that does not respond to other treatment.
Does a splint help thumb arthritis?
Yes. A splint that supports the base of the thumb reduces pain and improves function for many people, especially when worn at night and during activities that cause pain. A hand therapist can fit a custom splint if off-the-shelf splints are uncomfortable.
Can thumb arthritis be cured?
The cartilage damage cannot be reversed, but symptoms can be well controlled. For severe cases, surgery to remove the worn joint surface, usually by taking out the trapezium bone, relieves pain in most people and restores useful function.
Sources
This guide was written from current patient and clinical guidance, including:
- American Society for Surgery of the Hand: Thumb arthritis (basal joint arthritis)
- American Academy of Orthopaedic Surgeons (OrthoInfo): Arthritis of the thumb
- American College of Rheumatology: Guideline for the management of osteoarthritis of the hand, hip and knee
- MedlinePlus: Osteoarthritis
- NHS: Osteoarthritis of the hand