Thumb Base Arthritis

This leaflet provides general information to help you understand thumb base arthritis and the available treatment options.

Not everyone with thumb base arthritis needs surgery.

At the heart of my practice is Shared Decision-Making. Whether we pursue conservative management (Plan A) or surgical intervention (Plan B), the goal is to create a tailored treatment plan that aligns with your lifestyle, values, and functional goals.

The Anatomy of the Thumb Base

The thumb base is a mobile joint that lets you pinch and grip, relying on several structures working together.

How the Joint Works

A saddle-shaped joint gives the thumb its range:

• The thumb bone meets the trapezium wrist bone
• It works like a 'universal joint'
• This lets the thumb swivel, pinch and grip

The Cartilage

A smooth, slippery coating cushions the two bones so they glide over each other without friction, for pain-free movement.

What Goes Wrong

• The smooth surface thins over time
• The bones begin to rub together
• This causes pain, swelling and weakness
• Bone spurs and a 'bump' can develop

As It Advances

• Pinch and grip become weaker
• A visible bump appears at the thumb base
• The thumb can take a 'zig-zag' shape
• It often coexists with other hand problems

The Result

Everyday tasks like opening jars, turning keys and pulling zips become painful, though many people have X-ray changes with little pain.

What Is Thumb Base Arthritis?

Thumb arthritis occurs where the thumb bone meets the wrist (the trapezium). Over time the smooth cartilage that cushions these bones wears away, and when the bones rub together it causes pain, swelling and loss of strength.

Who Gets It

Some groups are affected more:

• Women, about nine times more often than men
• Usually between the ages of 40 and 60
• Seen on X-ray in many women over 55

What Causes It?

Wear of the joint over time, made more likely by:

• Age and previous heavy hand use
• Earlier injury to the thumb base
• A family tendency to arthritis
• Repetitive pinching and gripping

Symptoms & Examination

Symptoms

• Deep aching pain at the base of the thumb
• Worse when pinching or gripping
• Weak grip, stiffness and a visible bump

Examination

• The thumb base is tender and may be swollen
• A 'grind' test can reproduce the pain
• Grip, pinch and movement assessed

Diagnosis

• Usually confirmed by examination and X-ray
• Ultrasound or MRI occasionally for other causes

Treatment Options: A Shared Decision

I will discuss all available treatment options with you, explaining the benefits and risks of each. Your preferences, values, and lifestyle will be considered as we work together to create a treatment plan best suited to your needs — this shared decision-making process ensures you are fully informed and involved in your care.

Treatment Depends On

• How severe the pain and cartilage loss are
• How much it limits your daily activities
• Your response to splints and injections
• Your preferences and goals

Many people improve with simple measures — pain often settles on its own over time, and doing nothing is always an option.

Plan A — Non-Surgical

• Activity: new ways to grip that reduce strain on the joint
• Splints: a thumb splint supports the joint during heavy use
• Medication: NSAID gels or tablets reduce pain
• Injection: steroid or PRP can give useful pain relief

Plan B — Surgical

Considered when…

• Persistent Pain: despite splints, medication and injection
• Daily Life: pain and weakness limit hand function
• Trapeziectomy: the worn bone is removed to stop the rubbing
• Replacement: an artificial joint is now a reliable option
• Approach: chosen to suit your joint and your goals
• The Procedure: known as Trapeziectomy or Joint Replacement, surgery removes or replaces the worn joint to relieve pain, usually under anaesthetic. A separate leaflet will be provided for the surgery.

Management Pathway

Questions You May Wish to Ask

• What treatments should I try first?
• How long should I try them for?
• What improvement can I expect?
• What happens if I don't have surgery?