Base of Thumb Arthritis: Why Pinching, Gripping or Opening Jars Hurts
Struggling to open a jar, turn a key, or pinch something between your thumb and finger without a
sharp ache at the base of your thumb?
This is a common hand complaint and can be caused by base of thumb arthritis, also called
CMC joint osteoarthritis or basal thumb arthritis.
What is base of thumb arthritis?
The base of your thumb has a small, highly mobile joint called the carpometacarpal
(CMC) joint. It is formed by the trapezium bone and the base of the first metacarpal
bone.
This joint allows your thumb to pinch, grip and oppose your fingers, helping you
perform a huge range of precise and powerful movements.
However, this combination of high movement and load also makes the CMC joint a
common site for osteoarthritis.
Base of thumb arthritis is more common as we get older and is particularly common in
women.
Interesting fact: Thumb arthritis is more common in the non-dominant thumb
What does base of thumb arthritis feel like?
Common symptoms include:
Pain at the base of the thumb
Pain with pinching, such as turning a key, holding a pen or doing up buttons
Pain when opening jars, twisting lids or wringing out a cloth
A deep ache that may extend into the thumb or wrist
Stiffness, particularly in the morning
Swelling or a bony prominence at the base of the thumb
Reduced grip or pinch strength
In more advanced cases, changes in thumb position or deformity
What causes base of thumb arthritis?
Base of thumb arthritis can develop for a number of reasons, including:
Age-related changes
Previous thumb or wrist injury
Family history
Repetitive or forceful pinching and gripping
Differences in joint structure or stability
Sometimes, there is no single identifiable cause.
How is base of thumb arthritis diagnosed?
Diagnosis usually starts with a clinical assessment. Your hand therapist will assess your
symptoms, thumb movement, stability and function, including your pinch and grip strength.
A grind test may be used as part of the assessment, and your doctor may request an X-ray to
assess changes within the joint.
Importantly, having arthritis does not necessarily mean you will have pain or difficulty using
your hand. Some people have changes on an X-ray but very few symptoms, while others can
have significant pain despite relatively mild changes on imaging.
Your symptoms and hand function are therefore just as important when deciding on treatment.
“I have arthritis — is there anything that can help?”
Absolutely. There is often a lot you can do to manage painful base of thumb arthritis.
For people with painful or functionally limiting base of thumb arthritis, hand therapy is usually the
first step before considering surgery. The aim isn't to “fix” the arthritis, but to reduce pain,
improve thumb stability and function, protect the joint and help you continue doing the
things that are important to you.
How can hand therapy help?
Your hand therapist will assess your thumb, how you use your hand and which activities are
causing difficulty. Treatment can then be tailored to your symptoms, lifestyle and goals.
Splinting
A custom-made or fitted thumb splint can support and offload the CMC joint during painful
activities or flare-ups.
Depending on your needs, your therapist may recommend a custom-made thermoplastic splint,
soft neoprene-style splint or pre-fabricated CMC splint.
Proprioception, stability and strengthening
Proprioceptive and neuromuscular exercises can improve your awareness, control and
coordination of the thumb during movement, pinching and gripping.
Targeted strengthening can also help support the thumb and maintain pinch and grip function,
without unnecessarily aggravating the joint.
Joint protection and activity modification
Small changes to how you use your hand can make everyday activities easier.
Your therapist may recommend:
Built-up handles to reduce the force required from your thumb
Changing how you grip or pinch objects
Avoiding unnecessary forceful or prolonged pinching
Using both hands for heavier tasks
Modifying activities during painful flare-ups
The goal isn't to stop you doing the things you enjoy, but to find easier ways of doing them with
less stress on your thumb.
If symptoms aren't improving with appropriate hand therapy, your therapist can work with your GP
or specialist to determine whether medication, corticosteroid injection or a surgical opinion
may be appropriate.
Will base of thumb arthritis get worse over time?
Base of thumb arthritis can progress over time, but the rate of progression and the symptoms
experienced vary considerably between people.
The amount of arthritis seen on an X-ray does not necessarily predict how much pain or functional
difficulty you will experience.
The aim of hand therapy, splinting, exercises and joint protection strategies is to manage
symptoms, improve thumb stability and function, and reduce the load placed on the joint.
With appropriate management, many people continue using their hands for the activities they enjoy
and do not necessarily need surgery.
When should I get thumb pain checked?
If pinching, gripping or twisting movements are consistently painful — particularly if thumb pain is
affecting everyday activities such as opening jars, writing, cooking or using your phone — it's worth
getting assessed.
A hand therapist can assess your thumb and help identify what may be contributing to your
symptoms.
Book a hand therapy appointment
If you're experiencing pain at the base of your thumb, our hand therapists can assess your
symptoms and develop a treatment plan tailored to you.
We can provide custom-made splints, activity modification, joint protection strategies and
targeted exercises, including proprioceptive and stability exercises.
If further medical treatment or a surgical opinion may be appropriate, we can also work with your
GP or specialist to help guide the next step.
Not sure whether hand therapy is right for you? Contact us and we can help you understand
the next step.
Important information
This article provides general health information and is not a substitute for individual clinical
assessment or advice. Base of thumb pain can have different causes, and treatment will depend
on your individual circumstances. If you have significant pain, swelling, weakness or a sudden
change in thumb function, seek appropriate medical assessment.
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