12 Oct Thumb Base Arthritis: Understanding 1st CMC Joint Osteoarthritis
Thumb Base Arthritis: Understanding 1st CMC Joint Osteoarthritis
Have you noticed pain at the base of your thumb when opening jars, turning keys, gardening or gripping objects? You may be experiencing thumb base arthritis, also known as 1st carpometacarpal joint osteoarthritis (1st CMC OA).
Thumb arthritis is a common condition affecting the base of the thumb and is one of the most common locations for osteoarthritis in the hand. It can cause pain, stiffness, reduced strength and difficulty completing everyday activities that rely on gripping and pinching.
What is thumb arthritis?
In thumb CMC osteoarthritis, the smooth cartilage covering the ends of the bones within the joint gradually wears down. This can lead to increased friction, inflammation, stiffness and pain. The affected carpometacarpal (CMC) joint sits at the base of the thumb where the trapezium bone connects with the first metacarpal bone. The 1st CMC joint is saddle-shaped, allowing the thumb to move in multiple directions. These movements are essential for everyday tasks such as gripping, pinching and grasping objects.
What causes thumb arthritis?
Thumb CMC osteoarthritis usually develops due to gradual changes within the joint over time.
Factors that can contribute include:
- Ageing
- Genetics or a family history of osteoarthritis
- Repetitive thumb movements involving gripping and pinching
- Previous injury to the thumb joint
The thumb CMC joint is exposed to significant forces during everyday activities. Pinching in particular places high loads through the joint, which can increase stress on the cartilage and supporting ligaments.
What are the symptoms of thumb arthritis?
Symptoms can include:
- Pain at the base of the thumb
- Swelling and tenderness
- Aching after prolonged use
- Stiffness and reduced thumb movement
- Reduced grip and pinch strength
- Difficulty opening jars, bottles and containers
- Difficulty turning keys or door handles
- Difficulty gardening, using scissors or carrying objects
- A small bump developing at the base of the thumb
These symptoms can make everyday tasks more challenging and may affect hobbies, work and other activities.
How is thumb arthritis diagnosed?
A hand therapist will complete an assessment to understand how your thumb symptoms are affecting your function. This may include assessing thumb movement and flexibility, tenderness or swelling, grip and pinch strength and how your symptoms affect everyday activities. Your doctor may also request imaging such as an X-ray to assess changes within the joint and assist with diagnosis.
How is thumb arthritis treated?
The aim of treatment is to reduce pain, improve thumb function and help you continue participating in daily activities.
Treatment commonly involves a combination of splinting, exercise, education and activity modification.
Splinting
A custom-made thumb splint can provide support to the CMC joint by reducing painful movements, improving thumb positioning and reducing strain on the joint during activities.
Exercise
A tailored exercise program can help maintain thumb movement, strength, joint stability and hand function.
Joint protection and activity modification
Your hand therapist can provide strategies to reduce stress on the thumb joint. These may include changing how you complete painful tasks, avoiding prolonged or forceful pinching where possible, using larger handles or adaptive equipment and learning thumb-friendly techniques for daily activities.
Other treatment options may include heat therapy to reduce stiffness and soft tissue techniques.
Managing thumb arthritis long-term
Although thumb arthritis cannot be cured, symptoms can often be managed through regular prescribed exercises, maintaining thumb movement and strength, modifying aggravating activities and using appropriate splints or aids when needed.
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