Is This Why Your Thumb Hurts? The Hidden Cause of That Nagging Pain At The Base of Your Thumb
Finally, an explanation for that grinding, burning sensation that’s been driving you crazy
That Moment When Everything Clicks
If you’ve been experiencing a nagging pain at the base of your thumb…
If that pain gets worse when you try to grip something, twist a jar lid, or turn a key…
If you’ve been wondering whether it’s carpal tunnel, arthritis, or something else entirely…
Then what you’re about to discover could finally give you the answers you’ve been searching for.
My name is Dr. Sarah Mitchell, and in my 15 years as a hand specialist, I’ve seen thousands of patients walk into my office with the same confused, frustrated expression.
They point to the base of their thumb and say things like:
“It hurts right here, but I don’t know why.”
“It started as just a weird ache, but now it’s affecting everything I do.”
“I thought it might be carpal tunnel, but the pain is in the wrong place.”
“Opening jars has become impossible, and I don’t understand what’s happening.”
The Pain That Doesn’t Make Sense
Here’s what typically happens:
It starts subtly.
Maybe you notice a slight ache at the base of your thumb after a day of gardening or crafting.
You ignore it, thinking it’s just overuse.
But then it comes back.
And stays longer.
Soon, you’re experiencing a grinding, grating sensation when you move your thumb.
Sometimes it’s a dull throb.
Other times, it’s a sharp, burning pain that shoots up your thumb when you try to grip something.
You start avoiding certain activities.
Opening jars becomes a two-person job.
Turning keys requires both hands.
Writing for more than a few minutes becomes uncomfortable.
You might even start wondering if you’re developing carpal tunnel syndrome, since that’s what everyone talks about.
But the pain isn’t in your wrist or fingers. It’s right at the base of your thumb, where it meets your wrist.
What’s Really Happening
Here’s what’s actually causing your pain:
You likely have carpometacarpal arthritis—also known as CMC arthritis or thumb base arthritis.
Look at the image above.
See that joint where your thumb bone (the first metacarpal) meets the trapezium bone in your wrist?
That’s your carpometacarpal joint.
This joint is responsible for almost every gripping, pinching, and twisting motion your thumb makes.
It’s one of the most used joints in your entire body.
Over time, the smooth cartilage that cushions this joint can wear away.
When bone starts rubbing against bone, you get:
- That grinding, grating sensation when you move your thumb
- Sharp pain when gripping or pinching
- Stiffness, especially in the morning
- Weakness in your grip strength
- A dull, throbbing ache that can last for hours after use
Why This Isn’t Carpal Tunnel (And Why That Matters)
Many people mistake CMC arthritis for carpal tunnel syndrome because both affect hand function.
But they’re completely different conditions:
Carpal Tunnel: Numbness and tingling in your fingers from nerve compression in your wrist
CMC Arthritis: Pain, stiffness, and grinding sensation specifically at the base of your thumb from worn cartilage
This distinction matters because the treatments are completely different.
Carpal tunnel often requires nerve decompression surgery.
CMC arthritis responds well to conservative treatments like compression, warmth, and gentle support.
Why CMC Arthritis Affects Everything You Do
Here’s what makes this condition so frustrating:
Your thumb is involved in approximately 40% of all hand functions. When that one joint is painful and stiff, it impacts:
- Grip strength – Opening jars, bottles, and containers
- Pinch strength – Picking up small objects, buttoning clothes
- Key pinch – Turning keys, using scissors, writing
- Opposition movement – Touching your thumb to your other fingertips
This explains why CMC arthritis can make you feel like your entire hand is failing, even though the problem is localized to one specific joint.