Pain at the base of the thumb that becomes worse when opening a jar, turning a key, pinching, squeezing or using a strong grip is commonly caused by osteoarthritis of the thumb carpometacarpal joint. This is the first CMC joint, between the first metacarpal and the trapezium. Pain location alone is not enough to make the diagnosis, however: de Quervain tenosynovitis, scaphoid injury, disease in adjacent joints and nerve irritation can produce similar symptoms. Most patients start with non-operative treatment.
Polish version: Ból u podstawy kciuka — czy to zwyrodnienie stawu siodełkowego?
What is the thumb CMC joint?
The joint at the base of the thumb has a saddle-shaped geometry that allows a large range of motion. It lets the thumb move away from the palm, oppose the fingers and perform precise pinch. That mobility comes at the cost of substantial loading across a relatively small articular surface.
Over time, cartilage may deteriorate and the joint can become less stable. Imaging may show joint-space narrowing, osteophytes, subchondral sclerosis and sometimes subluxation of the base of the first metacarpal. An important point is that radiographic severity does not always match pain or functional limitation. Treatment decisions should be based on the patient and the symptoms, not on the X-ray alone.
What symptoms are typical?
- pain around the base of the thumb, usually on the palmar or radial side,
- pain when opening jars, turning keys, fastening buttons, opening packaging or using tools that require pinch,
- reduced grip and pinch strength,
- tenderness directly over the joint,
- sometimes crepitus or clicking with movement,
- in more advanced cases, visible widening or deformity at the base of the thumb.
Symptoms often develop gradually. Activities requiring forceful grip or loaded pinch typically provoke more pain than moving the hand freely without resistance.
How is this different from de Quervain tenosynovitis?
Both problems may be described simply as “pain on the thumb side,” but the area of greatest tenderness is usually different. With first CMC osteoarthritis, pain is centred at the base of the thumb around the joint. With de Quervain tenosynovitis, pain is typically higher at the radial styloid on the wrist and relates to the tendons of the first extensor compartment.
After a fall onto the hand, the diagnostic situation is different again. New pain on the radial side can result from a scaphoid fracture and should not automatically be attributed to osteoarthritis.
How is thumb CMC osteoarthritis diagnosed?
History and examination
The pattern of symptoms and the clinical examination are central. Assessment includes the exact pain location, range of motion, thumb stability, grip and pinch strength, and neighbouring joints and tendons. The grind test — axial loading with rotation of the first metacarpal — can support the diagnosis, but it is not a perfect test. A negative result does not exclude thumb-base osteoarthritis.
X-ray
Radiographs are useful when bony changes need confirmation, their extent matters, adjacent-joint disease must be considered or surgery is being planned. An X-ray is not necessarily required for every first mild episode with a typical presentation. Even marked radiographic osteoarthritis can coexist with limited symptoms, and the reverse can also occur.
Ultrasound
Ultrasound can demonstrate osteophytes, joint fluid and synovial changes while also assessing the soft tissues around the painful region. It can be particularly useful when differentiating joint disease from de Quervain tenosynovitis or another tendon problem. It can also guide a planned injection accurately. Ultrasound is not mandatory in every patient with a typical clinical presentation.
MRI
MRI is rarely the first-line test for typical first CMC osteoarthritis. It is more useful when symptoms are atypical, previous tests do not explain the pain, or another bone, ligament or cartilage abnormality is suspected.
How is thumb-base osteoarthritis treated without surgery?
Current British Society for Surgery of the Hand guidance supports a stepwise approach. Initial management is multimodal and non-operative, with additional options introduced if symptoms continue to cause meaningful functional limitation.
Load modification and exercise
The aim is not to stop using the thumb completely, but to reduce the most provocative loads and improve how everyday tasks are performed. Wider handles, jar-opening aids, using two hands instead of one and limiting prolonged forceful pinch can be helpful.
Exercises directed at thumb stability, range of motion and hand strength may reduce pain and improve function. Their intensity should be adjusted so that they do not provoke a prolonged flare of symptoms.
Brace
A brace that stabilises the base of the thumb can reduce pain during gripping activities. It does not necessarily need to be worn continuously. Some people benefit most during demanding tasks, while others use it for selected periods at rest as well. The type and schedule should match the symptoms and the functional demands on the hand.
Pain and anti-inflammatory medication
Medication can reduce pain temporarily but does not restore cartilage. Topical anti-inflammatory preparations are often considered for local symptoms. Oral medication needs individual assessment, particularly in people with gastrointestinal, kidney or cardiovascular disease or those taking anticoagulants.
Joint injection
If non-invasive treatment has not provided enough relief, an intra-articular corticosteroid injection may be considered. BSSH guidance places injection at this stage in the pathway. The goal should be realistic: an injection may reduce pain for a period, but it does not regenerate cartilage or remove the mechanical cause of osteoarthritis.
The evidence for injection efficacy is less consistent than its widespread use might suggest. Systematic reviews have found heterogeneous results, so the decision should take symptom severity, previous treatment and alternatives into account.
When does an orthopaedic surgeon consider surgery?
Surgery is considered when pain and functional limitation remain substantial despite appropriate non-operative treatment and continue to interfere with daily life, work or activity. A “bad X-ray” alone is not an indication for surgery.
One of the most commonly used operations is trapeziectomy, which removes the trapezium. Numerous modifications add ligament reconstruction, suspension of the first metacarpal or tissue interposition. Current BSSH guidance notes that available evidence has not demonstrated an advantage of adding interposition or ligament reconstruction over trapeziectomy alone.
This does not mean every patient should have the same operation. Procedure selection depends on age, deformity, neighbouring joints, functional demands and surgeon experience. More complex reconstruction should have a specific rationale rather than being performed automatically.
When should thumb pain be assessed more urgently?
- severe pain after a fall or other injury, especially with deformity, bruising or inability to use the thumb,
- rapidly increasing swelling, redness and marked warmth, particularly with fever,
- new or pronounced numbness or weakness in the hand,
- a thumb that becomes blue, pale or cold, or other signs of impaired circulation,
- rapidly progressive unexplained symptoms or involvement of several joints suggesting inflammatory disease.
Common questions
Can osteoarthritis be reversed?
Structural changes in cartilage and bone cannot simply be reversed by exercise, a brace or an injection. Pain and function can nevertheless improve substantially, which is why imaging severity does not determine how well the hand can function.
Do severe X-ray changes mean I need surgery?
No. The relationship between radiographic severity and symptoms is limited. Surgical decisions are based mainly on pain, loss of function and failure of appropriate previous treatment, with imaging as one part of the decision.
Is ultrasound always needed before an injection?
Not in every straightforward case. Ultrasound guidance allows the operator to visualise the needle and adjacent structures and confirm that medication reaches the intended location. It may be particularly useful with atypical anatomy, previous unsuccessful injections or diagnostic uncertainty.
References
- Gangopadhyay S, Jansen V, Khor WS, Gardiner MD, Burchette D, McKenna H. Guideline on managing thumb base osteoarthritis: The British Society for Surgery of the Hand Evidence for Surgical Treatment (BEST) findings and recommendations. J Hand Surg Eur Vol. 2025;50(5):576–586. DOI: 10.1177/17531934241313206.
- Hamasaki T, Laprise S, Harris PG, et al. Efficacy of Nonsurgical Interventions for Trapeziometacarpal (Thumb Base) Osteoarthritis: A Systematic Review. Arthritis Care Res (Hoboken). 2020;72(12):1719–1735. DOI: 10.1002/acr.24084.
- Merritt MM, Roddey TS, Costello C, Olson S. Diagnostic value of clinical grind test for carpometacarpal osteoarthritis of the thumb. J Hand Ther. 2010;23(3):261–267. PMID: 20452743.
This article is educational and does not replace a medical examination or individual treatment assessment.
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Content prepared by: Tomasz Poboży - orthopaedic surgeon.
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