A note on this column: This article is general medical information, not a description of a service offered at this practice. Dr. Ishiguro's surgical practice is focused on hip and knee conditions — he does not treat thumb base arthritis or other hand and wrist disorders. This column is written to help readers understand a common cause of hand pain and know when and how to seek the right specialist, typically a hand surgeon (an orthopaedic or plastic surgeon specialising in the hand), a rheumatologist, or a hand therapist.
What thumb base arthritis is
The thumb's unusual range of movement — swinging across the palm to touch each fingertip — depends largely on one joint at its base: the carpometacarpal (CMC) joint, also called the trapeziometacarpal joint or basal thumb joint. Here, the first metacarpal bone of the thumb sits on a small wrist bone called the trapezium. The two surfaces are shaped like interlocking saddles, which allows the thumb to move in many directions but also means that the joint relies on ligaments for stability and experiences high forces with every pinch and grip.
In thumb base arthritis (CMC osteoarthritis; known in Japan as boshi CM kansetsu-shō), the smooth cartilage covering these joint surfaces gradually thins and roughens. Over time this can lead to bone spurs, narrowing of the joint space, and, in more advanced stages, the base of the metacarpal drifting partly out of position. As with osteoarthritis elsewhere, the process is thought to involve a combination of factors — age, sex, genetics, joint shape and ligament laxity, and cumulative loading — rather than a single cause.
Who gets it
Changes of osteoarthritis on hand X-rays are extremely common with age, and they don't always cause symptoms. In the Japanese population-based ROAD study, which X-rayed both hands of 1,535 adults (average age in the mid-60s), radiographic hand osteoarthritis in at least one joint was found in about 90% of both men and women. The finger-tip (DIP) joints were affected most often — but when the authors looked at which changes were linked to pain, severe osteoarthritis of the DIP joints and of the first CMC joint was associated with hand pain, and more severe hand osteoarthritis overall was linked to weaker grip (Kodama et al., Mod Rheumatol, 2016).
Symptomatic thumb base arthritis is seen considerably more often in women than in men, and most commonly from around the age of 50 onward. A previous injury to the joint, such as a fracture at the base of the thumb, can also make arthritis more likely.
Key points at a glance
- The CMC joint at the base of the thumb is one of the most common sites of hand osteoarthritis
- Typical symptoms are pain at the base of the thumb with pinching, gripping, and twisting, and reduced pinch strength
- X-ray changes don't always match symptoms — some people with marked changes have little pain, and vice versa
- First-line care is non-surgical: education, joint protection, exercise, assistive devices, and splints where helpful
- Injections may give short-term relief for some people, but trial results are mixed
- Surgery is an option for persistent, disabling pain; several techniques exist, and trials have not shown one to be clearly better than another
Symptoms
The most typical symptom is pain at the base of the thumb, on the thumb side of the wrist, brought on by activities that involve pinching or twisting — turning keys or door handles, opening jars and bottles, writing, wringing out cloths, or holding a phone or tablet for long periods. People often notice weaker pinch and grip, dropping things, or difficulty with fine tasks such as buttons. Stiffness, swelling, or a grinding sensation may also occur.
In more advanced arthritis, a bump may develop at the base of the thumb, and the thumb can gradually take on a "zig-zag" posture — the base drifts inward towards the palm while the next joint (the MCP joint) bends backwards to compensate. This can make it harder to open the hand wide enough to grasp large objects.
How it is diagnosed
Diagnosis is usually based on a history and examination. A clinician will look for tenderness directly over the joint and may perform a "grind test", gently pressing and rotating the thumb metacarpal against the trapezium to see whether this reproduces the pain. Pinch strength and the alignment of the thumb are also checked.
Plain X-rays are the standard imaging test. They show joint-space narrowing, bone spurs, and any shift of the joint, and are often described using a staging system (such as the Eaton–Littler classification). X-ray stage helps describe the joint, but symptoms and function — not the X-ray alone — usually guide treatment decisions. Ultrasound or MRI are not routinely needed but may be used if another problem is suspected.
Several other conditions can cause pain in the same area, and they are sometimes present at the same time:
| Condition | Key distinguishing feature |
|---|---|
| Thumb base (CMC) arthritis | Tenderness right at the base of the thumb; pain on grind testing; arthritic changes on X-ray |
| De Quervain's tenosynovitis | Pain and tenderness slightly higher, over the tendons on the thumb side of the wrist; pain when the thumb is tucked in and the wrist bent towards the little finger |
| Carpal tunnel syndrome | Numbness and tingling of the thumb, index, and middle fingers, often worse at night |
| Scaphotrapezial (STT) arthritis | Arthritis of a neighbouring joint just above the CMC joint; distinguished on X-ray |
| Inflammatory arthritis (e.g. rheumatoid arthritis) | Typically involves several joints, with morning stiffness and swelling; blood tests may help |
Treatment options
International guidance emphasises that management should be individualised and based on shared decision-making, and that every person with hand osteoarthritis should be offered education and training in ergonomic principles, pacing of activities, and the use of assistive devices. Exercises to improve function and strength are recommended, and orthoses (splints) should be considered for symptom relief in thumb base arthritis. Topical anti-inflammatory gels are suggested as a first-line medication, with oral anti-inflammatories considered for limited periods; intra-articular steroid injections are generally not recommended for routine use, and surgery is reserved for people with structural abnormalities when other treatments have not been sufficiently effective (Kloppenburg et al., Ann Rheum Dis, 2019). Commonly used options include:
Commonly used treatment options
- Education and joint protection — understanding the condition, pacing tasks, and changing how painful tasks are done
- Assistive devices — wide-grip pens and utensils, jar openers, key turners, and electric tools that reduce pinch force
- Hand therapy and exercise — exercises to maintain motion and strengthen the muscles that stabilise the thumb, usually guided by a hand therapist or physiotherapist
- Splints (orthoses) — soft or rigid supports that hold the thumb base in a stable position, worn during activities or at night
- Pain relief medication — topical anti-inflammatory gels first, oral medication for limited periods, as advised by a physician or pharmacist
- Injections — corticosteroid (and in some countries hyaluronic acid) injected into the joint, sometimes under ultrasound guidance
- Surgery — for persistent, disabling pain despite non-surgical care; options include removing the trapezium (trapeziectomy), with or without ligament reconstruction and tendon interposition, joint fusion, and joint replacement
What the evidence shows
What the evidence shows — splints: A French randomised trial of 112 people with thumb base arthritis compared a custom-made neoprene splint, worn mainly at night, with usual care. There was no difference in pain at one month, but at 12 months the splint group had less pain and disability (Rannou et al., Ann Intern Med, 2009). However, a larger UK trial of 349 people found that when participants were already receiving a structured, therapist-supported self-management programme (education, joint protection, and exercise), adding a thumb splint gave no additional benefit for hand pain at eight weeks compared with the programme alone or with a placebo splint — all three groups improved (Adams et al., Rheumatology, 2021). Taken together, these trials suggest that splints can help some people, but that a good self-management and exercise programme is a central part of care.
What the evidence shows — non-surgical care in everyday practice: In a Dutch multicentre cohort of patients treated with a hand orthosis plus hand therapy, about 15% went on to have surgery over an average of 2.2 years. Among those who did not have surgery, pain improved significantly — most of the improvement occurred within the first six weeks and then stayed stable up to one year — although hand function scores changed little (Tsehaie et al., J Hand Surg Am, 2018).
What the evidence shows — injections: In a small double-blind trial of 40 people with moderate to severe thumb base arthritis, a corticosteroid injection into the joint did not give better pain relief than a saline placebo injection at 24 weeks (Meenagh et al., Ann Rheum Dis, 2004). A systematic review found that most studies report some short-term benefit from steroid injections, but that results are inconsistent and the effect tends to be short-lived (Fowler et al., Hand, 2015). A 2025 network meta-analysis of 13 randomised trials found no robust evidence favouring any injection treatment, with only low-quality evidence that corticosteroid and hyaluronic acid injections may be better than placebo for pain in the mid-term (Challoumas et al., J Hand Surg Eur Vol, 2025).
What the evidence shows — surgery: A Cochrane review of 11 randomised trials (670 participants) compared seven surgical procedures, including trapeziectomy alone, trapeziectomy with ligament reconstruction and tendon interposition (LRTI), joint fusion, and joint replacement. No procedure was shown to be superior to another for pain, function, or other outcomes, though the overall quality of evidence was low. Low-quality evidence suggested that adding LRTI to trapeziectomy may not provide additional benefit and may be associated with more adverse events (Wajon et al., Cochrane Database Syst Rev, 2015).
In practice, the choice of treatment depends on how much pain and functional limitation a person has, how they use their hands at work and at home, the stage of arthritis, and their own preferences — ideally discussed with a hand specialist and, often, a hand therapist.
What recovery generally looks like
Thumb base arthritis is a long-term condition, but symptoms often fluctuate, and many people manage well for years with self-management, exercise, and practical adjustments to daily tasks. Splints and exercise programmes usually need several weeks of consistent use before their effect can be judged. After surgery, the thumb is typically protected in a cast or splint for several weeks, followed by a period of hand therapy; regaining strength can take several months, and the details vary with the procedure and the surgeon's protocol.
When to see a specialist
It's worth having thumb pain assessed if it keeps you from everyday tasks, is getting steadily worse, is accompanied by noticeable swelling or a change in the shape of the thumb, or hasn't improved after several weeks of sensible self-care. Numbness or tingling, sudden swelling with redness and warmth, or pain and swelling in several joints with morning stiffness should also be checked, as these may point to a different condition. A hand surgeon, rheumatologist, or hand therapist can confirm the diagnosis with a simple examination and X-ray and help you find the options that fit your situation.
References (PubMed / Journal)
Kodama R, Muraki S, Oka H, Iidaka T, et al. Prevalence of hand osteoarthritis and its relationship to hand pain and grip strength in Japan: The third survey of the ROAD study. Mod Rheumatol. 2016;26(5):767-773. DOI: 10.3109/14397595.2015.1130673
Kloppenburg M, Kroon FP, Blanco FJ, Doherty M, et al. 2018 update of the EULAR recommendations for the management of hand osteoarthritis. Ann Rheum Dis. 2019;78(1):16-24. DOI: 10.1136/annrheumdis-2018-213826
Rannou F, Dimet J, Boutron I, et al. Splint for base-of-thumb osteoarthritis: a randomized trial. Ann Intern Med. 2009;150(10):661-669. DOI: 10.7326/0003-4819-150-10-200905190-00003
Adams J, Barratt P, Rombach I, Arden N, et al. The clinical and cost effectiveness of splints for thumb base osteoarthritis: a randomized controlled clinical trial. Rheumatology (Oxford). 2021;60(6):2862-2877. DOI: 10.1093/rheumatology/keaa726
Tsehaie J, Spekreijse KR, Wouters RM, et al. Outcome of a Hand Orthosis and Hand Therapy for Carpometacarpal Osteoarthritis in Daily Practice: A Prospective Cohort Study. J Hand Surg Am. 2018;43(11):1000-1009.e1. DOI: 10.1016/j.jhsa.2018.04.014
Meenagh GK, Patton J, Kynes C, Wright GD. A randomised controlled trial of intra-articular corticosteroid injection of the carpometacarpal joint of the thumb in osteoarthritis. Ann Rheum Dis. 2004;63(10):1260-1263. DOI: 10.1136/ard.2003.015438
Fowler A, Swindells MG, Burke FD. Intra-articular corticosteroid injections to manage trapeziometacarpal osteoarthritis — a systematic review. Hand (N Y). 2015;10(4):583-592. DOI: 10.1007/s11552-015-9778-3
Challoumas D, Rana V, Hamad A, Putti A, et al. Injection treatments for trapeziometacarpal joint arthritis: a network meta-analysis of randomized studies. J Hand Surg Eur Vol. 2025;50(6):823-825. DOI: 10.1177/17531934241288176
Wajon A, Vinycomb T, Carr E, Edmunds I, et al. Surgery for thumb (trapeziometacarpal joint) osteoarthritis. Cochrane Database Syst Rev. 2015;(2):CD004631. DOI: 10.1002/14651858.CD004631.pub4