CMJ Thumb Replacement

This leaflet provides general information to help you understand joint replacement surgery for painful thumb base arthritis.

This day-case procedure replaces the worn joint while keeping thumb movement.

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

Cartilage gradually wears away:

• 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.

About the Operation

Thumb base joint replacement removes the worn joint surfaces and fits an artificial joint to relieve pain while preserving thumb movement and strength. It is a day-case operation, suited to painful thumb base arthritis that limits daily life when keeping motion is a priority.

Why It's Done

The operation aims to:

• Relieve pain from the worn joint
• Preserve thumb movement and strength
• Restore pinch, grip and fine hand use

The Procedure, Step by Step

The operation, step by step:

• Anaesthetic: regional or general anaesthetic
• Removal: the worn joint surfaces are removed
• Implant: an artificial joint is fitted to the prepared bones
• Closure: dissolvable stitches, dressing and a supportive splint

Before, During & After Surgery

Recovery & Results

Recovery is a partnership. The timeline below is a guide — I will adapt it to your healing and your goals — this shared decision-making process ensures you are fully informed and involved in your care.

Recovery Milestones

• Splint: supports the thumb for the first weeks
• Hand therapy: guided movement begins early
• Stitches: dissolvable; reviewed at about 2 weeks
• Good recovery: movement by 6 weeks, fuller by 3 months

Results

Joint replacement gives good pain relief while keeping thumb movement and strength. Most patients return to daily tasks; implant wear or loosening is uncommon.

After Surgery — The First Weeks

• Dressing & Splint: a supportive splint protects the thumb early on
• Pain Relief: start painkillers before the block wears off and take regularly for 24–48 hours
• Hand Therapy: guided movement begins early to restore motion
• Scar Care: gentle scar massage with cream once healed

Risks & Complications

Uncommon, but possible

• Infection: uncommon; treated with antibiotics if it occurs
• Stiffness: some early stiffness that improves with therapy
• Implant Wear: wear or loosening is uncommon but can need revision
• Nerve Irritation: temporary numbness near the scar can occur
• CRPS: rare; prolonged pain and stiffness needing therapy

Return to Activity

This can be extremely variable and discuss with the surgeon. These are just guidelines.

• Desk work: 2–3 weeks
• Light manual work: 6–8 weeks
• Heavy manual work: 12–16 weeks
• Driving: once comfortable and safe for an emergency stop
• Movement: improves with therapy over 3 months

Questions You May Wish to Ask

• When can I use my hand normally again?
• When can I drive and return to work?
• How much improvement can I expect?
• What are the signs of a problem?