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Thumb Base (CMCJ) Osteoarthritis
Understanding the causes, symptoms and treatment options for osteoarthritis at the base of the thumb, one of the most common forms of arthritis in the hand.
What is Thumb Base (CMCJ) Osteoarthritis?
Thumb base osteoarthritis is wear-and-tear arthritis of the carpometacarpal joint (CMCJ), the joint at the base of the thumb where it meets the small bones of the wrist. As the smooth cartilage in this joint wears down, the joint becomes painful, stiff and sometimes enlarged. It is one of the most common sites of arthritis in the hand, particularly because of how much force passes through this joint during pinching and gripping.
Thumb Base (CMCJ) Osteoarthritis at a glance
What is it?
Wear-and-tear arthritis of the joint at the base of the thumb, where the thumb meets the wrist
Common symptoms
Pain at the base of the thumb, worse with pinching and gripping, along with swelling and stiffness
Who it affects
More common in women, from the 40s onwards, and in individuals with a genetic predisposition to osteoarthritis
Is it serious?
Not dangerous, but can significantly affect grip and pinch strength if it progresses
Treatment options
Splinting, activity changes, injection, or surgery
First step
A consultation and x-ray to confirm the diagnosis and grade the severity
Symptoms and how Thumb Base (CMCJ) Osteoarthritis presents
The main symptom is pain at the base of the thumb, worse with pinching and gripping activities such as opening jars, turning keys or writing. Other symptoms include swelling, a bony prominence at the joint, reduced grip and pinch strength, and stiffness that is often worse first thing in the morning.
Causes and risk factors for Thumb Base (CMCJ) Osteoarthritis
- Age, with symptoms most common from the 40s and 50s onwards
- Being female
- Joint laxity or hypermobility
- A previous thumb fracture or injury
- Repetitive pinching activities
- A family history of osteoarthritis
How is Thumb Base (CMCJ) Osteoarthritis diagnosed?
Thumb base osteoarthritis is usually diagnosed from your history and an examination, including a grind test that reproduces pain by compressing and rotating the joint. An x-ray confirms the diagnosis and shows how advanced the joint wear is, which helps guide treatment. Thumb base osteoarthritis can affect the first CMCJ alone, or it can affect the STT (scaphotrapeziotrapezoid) joint, or both joints. The pattern of the osteoarthritis can affect the recommended treatment.
Treatment options for Thumb Base (CMCJ) Osteoarthritis
Self-care measures for thumb base osteoarthritis
- Applying heat or cold, such as a warm compress or an ice pack, to ease stiffness and pain
- Wearing a thumb splint to rest and support the joint during activities that provoke pain
- Gentle stretching and strengthening exercises for the hand and thumb
- Protecting the joint by avoiding repetitive or forceful pinching and gripping, and using larger joints for load where possible, for example carrying bags on the forearm rather than gripping with the fingers
- Using ergonomic aids such as jar openers, larger-grip pens, and adapted kitchen utensils to reduce strain on the joint
- Simple wardrobe adjustments, such as slip-on shoes or Velcro fastenings, to reduce demand on the thumb
- Simple pain relief or anti-inflammatory medication, taken as directed
Mild to moderate symptoms are often helped by the self-care measures above, ideally guided by a hand therapist. A hand therapist is a physiotherapist or occupational therapist with additional training in conditions of the hand and upper limb, and can fit a splint correctly, tailor an exercise program, and advise on joint protection and equipment suited to your daily activities. If you have not already seen a hand therapist, it may be worth doing before your appointment, as it may improve your symptoms and will give Dr Tomlinson a clearer picture of what has already been tried. A corticosteroid injection into the joint can also provide good symptom relief, sometimes for months at a time. Dr Tomlinson refers patients who have basal joint arthritis to a radiologist for a corticosteroid injection under ultrasound guidance.
If symptoms are severe or not controlled by these measures, surgery may be recommended. Options include removing the affected trapezium bone (trapeziectomy) with a ligament reconstruction, or in select cases joint fusion or joint replacement. Which option suits you depends on your symptoms, activity levels and the appearance of the joint on x-ray.
When to see a hand surgeon about Thumb Base (CMCJ) Osteoarthritis
It is worth seeing a hand surgeon if you have persistent pain at the base of the thumb that is limiting everyday activities like opening jars or writing, or if splinting and simple measures have not helped.
What to expect at your Thumb Base (CMCJ) Osteoarthritis appointment
At your appointment, Dr Tomlinson will take a history of your symptoms, examine your thumb and hand, and arrange an x-ray if one has not already been done. Together you will discuss the treatment options that suit your situation.
If you have not already seen a hand therapist and tried non-surgical treatment for your basal joint osteoarthritis Dr Tomlinson recommends that you try this before discussing surgical options.
Frequently Asked Questions
What is thumb base osteoarthritis?
Wear-and-tear arthritis of the carpometacarpal joint (CMCJ), the joint at the base of the thumb where it meets the small bones of the wrist. As the smooth cartilage wears down, the joint becomes painful, stiff and sometimes enlarged.
What causes it?
Age, most commonly from the 40s and 50s onwards, being female, joint laxity or hypermobility, a previous thumb fracture or injury, repetitive pinching activities, and a family history of osteoarthritis.
What can I do myself?
A thumb splint, activity modification, joint protection, and simple pain relief or anti-inflammatory medication can help mild to moderate symptoms. Heat or cold, ergonomic aids such as jar openers, and small wardrobe adjustments such as slip-on shoes can also reduce strain on the joint day to day.
What can a hand therapist do?
Provide and fit a thumb splint, teach gentle stretching and strengthening exercises, advise on joint protection and ergonomic aids for daily tasks, and support your recovery with therapy if you have surgery.
What can a hand surgeon do?
Confirm the diagnosis on examination and x-ray, which shows how advanced the joint wear is and helps guide treatment. A referral can be arranged for a corticosteroid injection under ultrasound guidance, which can provide good relief, sometimes for months. If symptoms are severe or not controlled by these measures, surgery may be recommended, including removing the affected trapezium bone (trapeziectomy) with a ligament reconstruction, or in select cases joint fusion or joint replacement.
What can I expect from treatment?
Splinting and activity changes help many mild to moderate cases, and an injection can provide good relief for some time. Surgery is a well-established option aimed at relieving pain and restoring function, with the specific procedure depending on your symptoms, activity levels and the appearance of the joint on x-ray.
What happens if it's left untreated?
Pain and stiffness can continue to affect grip and pinch strength, making everyday tasks like opening jars or writing more difficult over time. Earlier assessment gives more treatment options.
Related conditions and treatments
Thumb base osteoarthritis affects the joint at the base of the thumb. If pain and stiffness instead affect the smaller joints further along the fingers, you may be dealing with finger osteoarthritis, or if the wrist itself is affected, wrist osteoarthritis.