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When Opening a Jar Becomes the Hardest Part of Your Day
Thumb base arthritis (CMC arthritis) is wear of the saddle-shaped joint where your thumb meets your wrist…and it’s the most common arthritis I treat in the hand.
The signature: a deep ache at the fleshy base of the thumb, worst with PINCHING. Opening jars. Turning keys. Wringing clothes. Pulling up pants. Writing for long stretches. Holding a phone.
Most people settle well with a splint, joint-protection habits and the right strengthening. Injections help flares. Surgery is for the joint that has failed all of that, and the main operation, a trapeziectomy, is reliable for pain.
…basically, the fifty small pinches that make up a normal day, each one now sending you a bill.
Here’s the honest framing upfront: this one is about MANAGEMENT more than cure. And managed well, most people stay comfortable, functional, and out of the operating room for years…often forever.
Managed badly, the thumb slowly collapses into the palm, the web between thumb and index tightens, and the hand that used to open wide around a bottle can’t anymore. That part is much easier to prevent than to undo.
What’s actually happening in there
The joint at the base of your thumb is between the thumb metacarpal and a small wrist bone called the trapezium. It’s shaped like two saddles stacked on each other…which is what lets the thumb swing across the palm to meet the other fingertips. That movement (opposition) is most of what makes a human hand a human hand.
The price of all that mobility: high forces through a small, loosely-packed joint. A firm pinch at the fingertips can load the thumb base with up to around 12 times that force. Pinch 2 kg at the tips, and the base is carrying far more.
Decades of that, and the cartilage wears.
The ligaments that hold the joint snug loosen, the metacarpal starts to slide off its saddle, the joint gets inflamed, then gritty. In later stages the thumb base squares off visually and the thumb loses its ability to open wide.
It’s more common in women, usually from the 40s onward (often noticed around menopause), and it often runs in families. See perimenopause and hand pain.
Important distinction: this is wear-and-tear arthritis of ONE specific joint. Not rheumatoid, not “arthritis spreading through my body”. One joint, one problem, one plan. If several finger joints are involved too, see hand osteoarthritis, joint by joint and the types of arthritis in the hand.
Thumb base arthritis symptoms: how you know it’s this
- Deep ache at the base of the thumb, at the fleshy mound, worse with pinch and grip, better with rest.
- Morning stiffness that loosens with movement, usually within about 30 minutes.
- Aching after use, often worse in the evening or the day after a heavy job.
- Weakening pinch, dropping small objects, struggling with buttons, keys and bottle caps.
- Later: a bump or squared-off look at the thumb base, and a thumb that bends backwards at the middle knuckle when you pinch (the “zigzag” thumb).
What it’s NOT: pain on the thumb-SIDE of the wrist with thumbs-up lifting (that’s De Quervain’s, a tendon problem, usually younger patients)…and not tingling (nerve territory). A thumb that clicks and locks when it bends is trigger thumb.
These two do get mixed up weekly in my clinic. Location and trigger tell them apart: base-of-thumb + pinch = arthritis. Side-of-wrist + lift = De Quervain’s. More lookalikes in thumb pain by location.
How it’s diagnosed: the grind test and the X-ray
- Grind test. The examiner holds your thumb metacarpal, pushes it gently down into the joint and rotates it. Pain or a gritty grinding at the base is a positive.
- Tenderness right over the joint line at the thumb base, plus a check of how far the thumb opens and whether the middle knuckle collapses in pinch.
- Pinch strength measured with a pinch gauge, so progress is a number, not a feeling.
- X-ray confirms it and stages it. Blood tests only if the pattern suggests an inflammatory arthritis.
(Please don’t grind your own thumb into the table to check. If pinching a jar lid already tells you, you’ve done the test.)
Thumb arthritis stages (Eaton)
Your X-ray report may mention an Eaton or Eaton-Littler stage. In plain words:
- Stage 1: the joint space looks normal or slightly wide. The ligaments are lax, the surfaces still intact.
- Stage 2: some narrowing, small bone spurs (under 2 mm).
- Stage 3: marked narrowing, larger spurs (2 mm or more), the metacarpal sliding partly off its saddle.
- Stage 4: the neighboring joint between the trapezium and the scaphoid is worn too.
The catch: the X-ray stage and your pain often don’t match. A stage 4 X-ray can belong to a thumb that barely complains, and a stage 2 joint can be miserable. Treat the thumb in front of you, not the picture.
When does it stop being a minor problem?
This condition creeps rather than crashes. It’s not loud.
The loss is quiet: you stop opening jars, someone else turns the stiff keys, you avoid the firm handshake…your world shrinks one pinch at a time, and it happens so gradually most people don’t notice they’ve adapted around it.
The point to act is when you catch yourself avoiding things.
Not when the pain becomes unbearable…by then, months of strength and habit have already been lost. Avoidance is the alarm.
In Closing Window terms, the worn cartilage isn’t the window. That’s already done, and no exercise grows it back. The window that’s still OPEN is the web space and the alignment: a thumb that’s still opening wide and pinching in a round “O” can be kept that way. Once the web tightens and the thumb has collapsed into a zigzag for months, the window is closing, and a splint and stretches are working uphill.
Thumb arthritis treatment: what actually works
- A well-fitted splint. Supports the base joint during heavy-use hours. For many patients this alone changes daily life.
- Joint protection. Not surrender…engineering. You’re redistributing force away from one worn joint.
- The right strengthening. Done right, muscle support takes real load off the joint surfaces. Done wrong (heavy pinch exercises into pain), it feeds the fire.
- Calming a flare. Anti-inflammatory gel rubbed over the joint is a sensible first medicine for hand osteoarthritis, if your doctor or pharmacist agrees. Warm water in the morning loosens stiffness. See ice or heat for hand pain.
- Injection for a badly flared joint.
- Surgery for the joint that’s failed everything and is stealing quality of life.
Thumb arthritis splint: which one and how long
- Type: a short, hand-based thumb CMC splint that holds the base joint and leaves the wrist and the thumb tip free. Some people also need the middle knuckle blocked from bending backwards. A longer forearm-based thumb spica is for a very flared joint or when the wrist joins in.
- Soft or rigid: neoprene splints are comfier and many people wear them more. Rigid custom-molded thermoplastic gives more support. The best splint is the one you’ll actually wear.
- Hours: in a flare, most of the day for 2 to 4 weeks. After that, for the jobs that hurt (cooking, gardening, writing, driving) and at night if you wake sore or stiff.
- How long before judging it: give it 4 to 6 weeks of regular use. Many people keep one for flares long-term.
- Fit matters enormously. A pharmacy splint that pokes the wrong spot gets abandoned in a drawer by the same week.
See the short thumb CMC splint and thumb spica splints. If the web space is already tightening, a C-bar first web space splint holds it open, usually at night.
Thumb arthritis exercises: what to strengthen, what to avoid
The aim is a thumb that’s held stable by muscle, not by a worn joint grinding into place. Do these once or twice a day, pain-free or close to it. A little aching that’s gone within an hour is fine.
- Web space stretch. Gently open the thumb away from the index finger, hold 20 to 30 seconds, 3 times. Keeps the web from closing.
- The “O” pinch. Touch thumb tip to index tip making a round O, middle knuckle slightly bent, not collapsed backwards. Hold 5 seconds, 10 reps. This is the pattern everything else builds on.
- First dorsal interosseous. The muscle in the web on the back of the hand. Hand flat on the table, push the index finger sideways towards the thumb against your other finger, hold 5 to 10 seconds, 10 reps. It helps pull the metacarpal back onto its saddle.
- Thenar muscles. Hand flat, palm up, lift the thumb straight up towards the ceiling against a light rubber band, hold 5 seconds, 10 reps.
- Avoid: squeezing hard putty or grip trainers, heavy key pinch (thumb pad pressed against the side of the index finger), and any exercise that pushes the thumb into the palm. Those load exactly the surfaces that are worn.
Full program with progressions: thumb base arthritis exercises and joint protection.
Joint protection gadgets that actually earn their place
- Jar opener, ideally one mounted under a cabinet so both hands turn the jar, not a thumb.
- Key turner that slips over the key head so you turn with the whole hand.
- Fat grips on pens, cutlery, toothbrush and garden tools. Wider handle, less pinch force.
- Spring-loaded scissors and pruners, so the thumb only closes them.
- Lever taps, pump bottles, an electric can opener and ring-pull tools.
- Habits that cost nothing: two hands on the kettle and pots, carry bags on the forearm, slide things instead of pinch-and-lift, press spray bottles with the palm.
You cannot un-wear cartilage. But you can absolutely change how much load the worn joint carries every day…and that changes everything about how it feels.
Do steroid injections work for thumb arthritis?
- What they do: settle a badly flared joint for a period, often weeks to a few months. Useful tool, not a plan by itself.
- Who does best: earlier-stage joints tend to get more out of them than late-stage ones.
- Use the quiet time. The weeks after an injection are the window to start splinting and strengthening properly, not to go back to heavy pinching.
- Other injections (hyaluronic acid, PRP) are offered too. The evidence for them is mixed.
- How many: most doctors limit how many go into one joint. See steroid injections for hand pain: how many?
Thumb arthritis surgery options
Surgery comes in when the splint, protection, exercise and injections have had a fair go and the thumb is still running your day. Most managed-early thumbs never get here.
- Trapeziectomy. The commonest operation: the worn trapezium bone is removed and the gap fills with firm scar. Reliable for pain. Some surgeons add a tendon sling (LRTI, ligament reconstruction and tendon interposition); results with and without it are much closer than the debate suggests. Expect 4 to 6 weeks in a cast or splint, about 3 months for everyday life, and 6 to 12 months for full pinch strength. See trapeziectomy recovery week by week.
- Fusion (arthrodesis). The joint is fixed solid. Strong and stable, but the thumb can’t fully flatten or swing across the palm the same way. Usually offered to younger people doing heavy manual work. The bone takes roughly 8 to 12 weeks to fuse, protected in that time.
- Joint replacement. A small artificial joint keeps the thumb’s length and movement, and recovery can be quicker. It’s newer, not offered everywhere, and carries risks of loosening or dislocation. Usually for older, lower-demand hands with good bone.
- Early-stage options. For stage 1 to 2 joints a few surgeons offer ligament reconstruction or a small bone realignment (osteotomy) to unload the joint.
Whichever it is, the rehab after is a months-long project…and the months after surgery decide more of the result than most people expect.
Living with it: work, driving, hobbies
- Desk work: a wider mouse, a stylus or fat pen for writing, and voice typing for long emails.
- Driving: hold the wheel with an open palm, not a thumb wrapped hard around it. Push-button starts and a key turner for older cars.
- Gardening and DIY: padded gloves, fat-handled tools, ratchet pruners, and short sessions with breaks. See gardening hand and thumb pain.
- Knitting, sewing, crafts: thicker needles, 20 to 30 minute blocks, and the splint on for longer projects.
Does thumb base arthritis get worse?
- The X-ray usually changes slowly, over years.
- The pain often comes in flares lasting weeks, with quieter months in between. A flare isn’t proof it’s racing ahead.
- Function is the part you control. Keep the web open, keep the “O” pinch, spare the joint from heavy pinching, and most people keep doing what matters to them.
What a hand therapist does differently
- Confirms it’s the base joint and not De Quervain’s, a trigger thumb or a nerve problem.
- Fits the splint to your thumb and your day, so it actually gets worn.
- Retrains how you pinch, so the thumb stops collapsing into a zigzag under load.
- Measures pinch strength at each visit, so you can see progress before you feel it. See what a hand therapist actually does.
Get it checked today if
- The thumb base is suddenly hot, red and swollen, or you have a fever. Infection, gout and crystal arthritis can all flare here.
- The pain started with a fall or a forced bend of the thumb, with swelling or bruising. That’s a possible fracture or ligament tear, not arthritis.
Get it checked if
- You’ve started avoiding jars, keys, buttons or handshakes.
- The thumb won’t open wide anymore, or the middle knuckle bends backwards when you pinch.
- There’s tingling or numbness in the thumb, index and middle fingers. Carpal tunnel often travels with thumb arthritis.
- Several joints in both hands are swollen, with morning stiffness lasting well over an hour.
- A splint and exercises have had 6 to 8 honest weeks and nothing has changed.
Thumb-base pain in people who pinch for a living isn’t always arthritis. If that’s you, see massage therapist thumb pain, nail technician thumb pain or pottery wrist and thumb pain.
Already had the operation and something feels off? See trapeziectomy complications.
The cartilage is already worn. How much of your day the thumb still owns is up to you.
Written by Nigel Chua, hand occupational therapist in practice since 2005. Thousands of hands, wrists and elbows assessed and treated. My credentials are here. This article explains; it doesn’t examine. A thumb you’ve started planning your day around deserves a proper assessment.
Every article on this site is written using the Closing Window Method: name the window your condition runs on, find where you are in it, and act while it’s still open.