Thumb Joint Replacement for Thumb Arthritis (Rhizarthrosis)

You have arthritis at the base of your thumb, called rhizarthrosis. Your surgeon has recommended a thumb joint replacement, also known as a trapeziometacarpal prosthesis. To help you make an informed decision, it’s important to understand the surgery, the possible risks, and what to expect after the operation.

Why have a prosthesis?

Rhizarthrosis is a type of arthritis that affects the joint at the base of your thumb — where the trapezium bone and the first metacarpalbone meet. This joint wears out over time, causing pain, loss of strength, and eventually, thumb deformity. It also becomes stiff, making it hard to grip or pinch objects.

At the beginning, non-surgical treatments like splints, cortisone injections, or hyaluronic acid injections can help with pain. But if these treatments stop working or the thumb becomes more deformed, surgery is often the best option.

A simple X-ray usually confirms the diagnosis. Sometimes, a CT scan is needed for a more detailed view of the joint.

How does the surgery work?

The operation is done under regional anesthesia (you stay awake, but your hand and forearm are numb). A small cut, about 3 cm long, is made at the base of your thumb.

The surgeon removes the damaged joint tissue and places a prosthesis made of three parts:

• a cup inside the trapezium bone,
• a stem inside the metacarpal bone,
• a small head that helps keep the tendons and ligaments tight and working properly.

Possible complications during surgery

Some minor injuries can happen, such as:

• small nerve damage (causing numbness or tingling),
• injury to a nearby artery.

These are usually not serious. A fracture of the metacarpal or trapezium can happen, especially if the bone is fragile (osteoporosis). If this happens, the surgeon may need to change the surgical plan.

What to expect after surgery

Movement exercises usually begin in the first week. Your wrist and thumb will be in a splint for about 4 weeks. Daily activities can be restarted slowly, but avoid vibration-heavy tasks (like power tools) for 2 months.

The surgery is meant to reduce pain and restore the pinch function of your thumb. The prosthesis usually lasts around 15 years, but it may wear out sooner if the thumb is used too much.

Long-term complications (rare)

• Complex regional pain syndrome (CRPS): painful swelling that limits movement.
• Nerve issues: scar sensitivity or temporary numbness in the thumb and index finger.
• Tendonitis, like De Quervain’s syndrome.
• Prosthesis dislocation, which may need another surgery.
• Stiffness from extra bone forming around the joint.
• Implant loosening if the bones are weak.
• Allergy to metal, causing pain or redness at the scar.

Before and after the operation

Before surgery:

• Keep your hand clean.
• Remove nail polish and jewelry.

The surgery is usually done as a day case (you go home the same day). After surgery, your wrist and thumb will be supported with a splint or bandage. You’ll go home after seeing the surgeon and receiving your prescriptions (for pain, work leave, etc.). It’s best to have someone with you when going home.

This surgery is a long-lasting solution to relieve pain and improve thumb function; especially when you follow all the instructions given after surgery.