In this article
A thumb arthritis test is a clinician's examination of the joint at the base of the thumb, the carpometacarpal (CMC) or basal joint, read together with your symptoms and X-rays. The grind test is one maneuver within that assessment: across four published studies it correctly cleared 80% to 100% of thumbs without arthritis but detected only 12.5% to 53% of arthritic thumbs, so a negative grind test on its own is weak evidence against thumb arthritis.[1][3][4]
Sources and directory links checked October 28, 2026. This guide describes published examinations, not a self-test or a treatment recommendation.
Key takeaways
- The American Academy of Orthopaedic Surgeons (AAOS) describes thumb arthritis assessment as a symptom and injury history, an examination of tenderness, swelling and thumb motion, and X-rays of the CMC joint.[1]
- The grind test detected between 12.5% and 53% of arthritic thumbs in studies by Model (2016), Arnold (2022), Merritt (2010) and Gelberman (2015), depending on the examiner and the reference standard.[3][4][5][6]
- The same studies reported grind test specificity of 80% to 100%, so a positive grind test points toward arthritis more reliably than a negative one rules it out.[3][4][5][6]
- Other maneuvers detected more cases in individual studies: the lever test reached 82% sensitivity in Model's study and the adduction test 0.94 in Gelberman's.[3][6]
- X-rays confirm the diagnosis by showing joint-space narrowing or extra bone growth, according to AAOS and the American Society for Surgery of the Hand (ASSH).[1][2]
- AAOS reports that women are 2 to 3 times more likely than men to develop thumb base arthritis, and that age over 50 raises the likelihood.[1]
What does a clinician check for thumb arthritis?
The American Academy of Orthopaedic Surgeons describes an assessment that includes symptom history, previous injuries, tenderness, swelling and thumb movement. Its patient guide also describes X-rays showing joint-space narrowing or extra bone growth.[1]
The thumb carpometacarpal, or CMC, joint is the joint at the base of the thumb near the wrist. This page concerns that joint, rather than every joint or cause of pain in the thumb.[1]
The American Society for Surgery of the Hand also calls thumb arthritis basal joint arthritis. Its guide distinguishes the physical examination from X-ray confirmation.[2]
Thumb arthritis is usually assessed by a primary care physician, an orthopaedic or plastic surgeon who specializes in the hand, or a rheumatologist when inflammatory arthritis is possible. Certified hand therapists often take part in examination and rehabilitation; Merritt's grind test study used two therapists as examiners.[5]
| Part of the assessment | What the clinician records |
|---|---|
| History | Symptoms, past injuries to the hand and thumb, and the activities that make pain worse.[1] |
| Physical examination | Tenderness and swelling at the thumb base, how well the thumb moves, and provocative maneuvers such as the grind test.[1] |
| X-rays | Narrowing of the space between the bones and extra bone growth around the joint.[1][2] |
What is the thumb grind test?
The thumb grind test, also called the CMC grind test or axial grind test, is a provocative examination maneuver for basal joint arthritis. AAOS describes the clinician pressing the thumb into its base joint while rotating it at the same time. Pain, crunching or a grinding sensation counts as a positive result and raises suspicion of arthritis.[1]
The grind test stresses the trapeziometacarpal joint, where the first metacarpal of the thumb meets the trapezium bone of the wrist. Trapeziometacarpal, CMC and basal joint are three names for the same joint in the studies and patient guides cited here.[2][6]
Researchers have compared the grind test with other provocative maneuvers: the lever test in Model's study, the seesaw test in Arnold's study, and the adduction and extension tests in Gelberman's study.[3][4][6]
What did studies of the thumb grind test measure?
Four diagnostic studies reported how often the grind test agreed with a reference diagnosis. Model combined symptoms and imaging; Arnold used imaging stages, so their results have different reference definitions.[3][4]
Sensitivity is the proportion of reference-positive cases with a positive examination; specificity is the proportion of reference-negative cases with a negative examination.[3]
The table preserves each study's population and classification rather than ranking the tests or calculating a personal diagnosis.
| Original study | People and joints | Reference used | Reported examination results |
|---|---|---|---|
| Model et al., 2016 | 62 people; 121 hands analyzed, including 100 symptomatic and 21 asymptomatic hands | Thumb-base pain history plus radiographic arthritis | Grind: sensitivity 41%, specificity 100%. Lever: sensitivity 82%, specificity 81%.[3] |
| Arnold et al., July 2022 issue | 80 people enrolled; 68 with complete reference imaging, including 24 imaging-positive and 44 controls | Second image reading: Eaton stages 2-4 versus 0-1 | Surgeon: grind 12.5% sensitivity and 90.9% specificity; seesaw 70.8% and 81.8%. Pooled fellows: grind 16.7% and 97.7%; seesaw 41.7% and 86.4%.[4] |
| Merritt et al., 2010 | 70 thumbs in 54 people with various hand disorders | Radiological evaluation by a hand surgeon | Two therapists' grind-test sensitivities were 42% and 53%; specificities were 80% and 93%. The abstract does not label examiner-specific pairings.[5] |
| Gelberman et al., 2015 | 129 patients from two outpatient offices | Standardized examination and radiographs; exact case-classification rule unavailable in the abstract | Grind: sensitivity 0.44 (CI 0.30-0.59), specificity 0.92 (CI 0.84-0.97). Adduction: sensitivity 0.94 (CI 0.82-0.98), specificity 0.93 (CI 0.86-0.97).[6] |
Read together, the four studies agree on one pattern: the grind test was specific but insensitive. It rarely flagged thumbs without arthritis, and it missed roughly half or more of the thumbs that had it.[3][4][5][6]
Why do the studies give different test results?
Model's study assessed both hands in many participants; its comparison hands were asymptomatic hands of enrolled patients, not a separately recruited healthy group. This was an examination study, not a treatment trial or long-term follow-up. The table above reports its sensitivity and specificity, not its separate pain-reproduction scores.[3]
Arnold's study counted the same patients' surgeon and fellow examinations separately. Its accuracy table excluded 12 people without the second image reading. That reading occurred at least one month later; this was image reassessment, not a month of patient treatment follow-up. Its surgeon-versus-fellow figures are separate estimates, not confidence intervals.[4]
Merritt's original abstract was available, but its full text was not inspected. We report its sensitivity and specificity as published, not a predictive probability for an individual reader.[5]
Gelberman's report was also read at abstract level. It labels the intervals CI without specifying their confidence level there. The study was cross-sectional and did not report treatment outcomes or a follow-up period in the abstract.[6]
Examiner experience, the patients recruited and the reference standard all shift these figures. A surgeon and fellows examining the same patients in Arnold's study produced different grind test sensitivities, 12.5% and 16.7%.[4]
What do X-rays show in thumb arthritis?
X-rays help confirm thumb arthritis by showing narrowing of the space between the bones and extra bone growth, or bone spurs, around the base joint, according to AAOS.[1] The Hand Society's guide also describes X-rays as the way to confirm a diagnosis suggested by the physical examination.[2]
Studies often grade thumb base radiographs with the Eaton classification, which runs from early to advanced joint change. Arnold's study counted Eaton stages 2 to 4 as imaging-positive and stages 0 to 1 as negative.[4]
X-ray findings and symptoms do not always match. AAOS notes that some people have no symptoms despite X-rays showing advanced arthritis, and that some painful thumbs settle over time with or without treatment.[1]
Who is most likely to have thumb arthritis?
Thumb base arthritis is common and becomes more likely with age. AAOS reports that women are 2 to 3 times more likely than men to develop it. It also lists age over 50, a family history, excess weight, an earlier thumb or wrist injury, loose joints, frequent gripping or pinching work, and smoking as factors that raise the likelihood.[1]
The American Society for Surgery of the Hand calls it the second most common arthritis in the hand, after arthritis of the last joint of the fingers, and notes it typically appears after age 40.[2] Typical symptoms include pain at the thumb base when pinching, gripping or turning a key, weak pinch, swelling, a bump at the base of the thumb and reduced motion.[1]
What else can cause pain at the base of the thumb?
Osteoarthritis is the type of arthritis that most often affects the thumb base, according to AAOS, but it is not the only one.[1] The Hand Society notes that inflammatory conditions such as rheumatoid arthritis and lupus can also damage the basal joint.[2] The differences between the two are set out in our comparison of osteoarthritis and rheumatoid arthritis and on the rheumatoid arthritis condition page.
Clinicians also consider tendon problems near the wrist such as de Quervain tenosynovitis, old fractures or ligament injuries, and arthritis in the neighboring scaphotrapezial joint. Separating these is one reason the examination is paired with imaging rather than resting on a single maneuver.
Hand arthritis often involves more than one joint. Our overview of arthritis in the hands covers the finger joints, and the osteoarthritis condition page describes the disease across the body.
Can you use these studies as a thumb arthritis self-test?
Model's examinations were performed by trained investigators, and Arnold's by a surgeon and fellows. Neither full-text study tested a self-administered online quiz. This page therefore provides no maneuver instructions, scoring threshold or personal interpretation of a positive or negative result.[3][4]
Pain at the thumb base that interferes with daily activities is the point at which the Hand Society suggests seeing a surgeon.[2] A clinician's examination and an X-ray answer the question a home maneuver cannot: which joint is involved and how advanced the change is.
What can you ask about thumb arthritis treatment?
The Hand Society's overview names bracing, occupational therapy, medications, injections and surgery among treatment categories. That is a description of the options its guide discusses, not a recommendation that any category fits an individual reader.[2]
AAOS lists ice, activity changes, a splint that supports the thumb base, gentle exercises with a hand therapist, oral NSAIDs such as ibuprofen or naproxen, topical diclofenac gel, and steroid injections into the joint as nonsurgical options. It notes that injection relief can wear off and that injections carry risks.[1]
When nonsurgical care no longer helps, surgical options include removing the trapezium bone (trapeziectomy), often with tendon support known as ligament reconstruction and tendon interposition (LRTI), fusing the joint, suspension arthroplasty, or replacing the joint with an implant. AAOS states that research has not shown one procedure to be better than the others at relieving pain and improving function.[1]
Regenerative injections such as platelet-rich plasma (PRP) are usually cash pay, and the evidence for them in thumb CMC arthritis is thin. The Hand Society states there is no convincing evidence that any medication or supplement prevents thumb arthritis from progressing.[2] Our arthritis treatment guide, osteoarthritis treatment overview and PRP therapy guide describe what each option involves and where the research stands.
Useful appointment questions include: Which joint are we discussing? What did the examination and images each show? What alternatives explain the symptoms? What is the purpose of each proposed option, and what is included in the quoted charge? Bring questions about the assessment rather than a score calculated from this article.
For broader terminology, read our osteoarthritis guide. Its general discussion is separate from the thumb-specific examination studies summarized here.
Where can you compare PRP clinic records?
If a care discussion has already turned to PRP, the PRP clinic directory is a way to compare recorded listings. In Regenerated.com's September 2026 export of 9,042 US clinic records, 2,082 listed PRP across 48 states plus DC. Source: seo/clinics-export-2026-09.csv, summarized in data/directory-facts/prp.json. This is directory coverage, not a count of thumb arthritis specialists or evidence that PRP is appropriate for thumb pain.
State-level browsing is available for PRP clinics in Colorado, PRP clinics in Indiana and PRP clinics in Minnesota. These pages group recorded services by state; they do not establish a thumb-specific service at each clinic.
Two profiles with PRP recorded are Texas Health Care Bone & Joint in Fort Worth, Texas and Kristofer J. Jones in Los Angeles, California. These are examples, not endorsements. Confirm the clinician's credentials, thumb-assessment services, proposed procedure and fees directly; a category label does not establish any of those details.
Clinics that record arthritis care more broadly are grouped in the national arthritis treatment clinic list. Listing order there is not paid ranking, Featured slots are labeled and capped, and Verified means a clinic completed credential checks, not that it spent money. Regenerated.com is free for patients, inclusion is not an endorsement, and the guide to Featured, Verified and organic listings explains each label.
Frequently asked questions
Is the grind test the whole thumb arthritis assessment?
No. The grind test is one maneuver inside a wider assessment. AAOS describes a clinician asking about symptoms, past hand and thumb injuries and painful activities, checking tenderness, swelling and motion at the base of the thumb, and then using X-rays to look for joint-space narrowing or extra bone growth. A painful or gritty grind test raises suspicion of arthritis, and the X-ray helps make the diagnosis.[1]
Does a study sensitivity of 41% mean a 41% chance I have arthritis?
No. Model's 41% is the proportion testing positive among the study's reference-positive hands, not a personal probability after an examination. Turning a test result into an individual probability also needs the test's specificity and how common thumb arthritis is among people like you, which a clinician weighs alongside your history and X-rays. A single study figure cannot be applied to one thumb on its own.[3]
How many people were in the seesaw test study?
Arnold's study enrolled 80 people; 68 had the reference imaging needed for its accuracy analysis, made up of 24 imaging-positive patients and 44 controls. A hand surgeon and fellows each examined those patients, and their results were reported as separate estimates. Surgeon and fellow examinations of those patients do not double the number of people, so the accuracy figures rest on 68 participants.[4]
Does a PRP listing confirm thumb arthritis treatment is available?
No. The directory records a broad PRP service category, not a thumb-specific service. Ask the provider whether it evaluates thumb base problems, who performs the examination, what imaging it uses and what the quoted fee includes. Evidence for PRP in thumb CMC arthritis is limited, so the listing is a starting point for questions rather than a treatment recommendation or an endorsement.
What does a positive grind test mean?
A positive grind test means that pressing and rotating the thumb into its base joint reproduced pain, a gritty feeling or a grinding sensation, which AAOS describes as a reason to suspect arthritis. Because published studies found the grind test specific but insensitive, a positive result points toward arthritis, while a negative result does not exclude it. A clinician reads either result together with your history and X-rays.[1][3]
Which thumb arthritis test was most accurate in studies?
No single maneuver was most accurate in every study, because each used different patients, examiners and reference standards. Gelberman reported adduction test sensitivity of 0.94 and specificity of 0.93, Model reported lever test sensitivity of 82%, and Arnold's surgeon detected 70.8% of imaging-positive thumbs with the seesaw test against 12.5% with the grind test. X-rays remain the standard way to confirm the diagnosis.[3][4][6]
Sources
- AAOS: Arthritis of the Thumb. Checked October 28, 2026.
- American Society for Surgery of the Hand: Thumb Arthritis. Checked October 28, 2026.
- Model et al. (2016): Evaluation of Physical Examination Tests for Thumb Basal Joint Osteoarthritis. Checked October 28, 2026.
- Arnold et al. (2022 issue): Evaluation of the Seesaw Test as New Diagnostic Test for Thumb CMC Osteoarthritis. Checked October 28, 2026.
- Merritt et al. (2010): Diagnostic value of clinical grind test for carpometacarpal osteoarthritis of the thumb. Checked October 28, 2026.
- Gelberman et al. (2015): Trapeziometacarpal Arthritis: A Prospective Clinical Evaluation of the Thumb Adduction and Extension Provocative Tests. Checked October 28, 2026.