If you’ve been dealing with thumb pain or rhizarthrosis, which is arthritis in the base joint of your thumb, there is news from science. A prosthesis called scapho-metacarpal dual mobility might help your thumb move better, reduce pain, and keep its length.
Here are some key findings:
- A new prosthesis was tested on patients after their previous surgeries didn’t work.
- Thumb function and grip strength improved greatly.
- Only minor complications were seen in this study.
In this article:
What is rhizarthrosis?
Rhizarthrosis is arthritis in the trapeziometacarpal joint that connects your thumb to your wrist. The name uses trapezio because of the small bone at the base of your thumb, and metacarpal because it joins the longer thumb bone.
This condition is common in women over 50, and it can cause pain, reduced grip strength, and trouble moving the thumb. You might notice thumb shortening or stiffness too.
How does the Touch prosthesis help?
The Touch prosthesis is a type of artificial joint for the thumb. Instead of removing the trapezium bone completely or fusing the bones, this device uses a ball in a socket. The cup part of the prosthesis sits inside the scaphoid bone, a wrist bone near the thumb.
This design aims to keep thumb mobility while avoiding the problems of other surgeries, like permanent stiffness or shortened thumbs.
What were the study results?
Let’s look at the study findings.
Who participated?
11 patients were studied, with 13 thumbs treated. Some had both hands treated. These patients had already had unsuccessful thumb surgeries before.
What changed?
After surgery:
- Thumb movement improved. Patients scored 9 out of 10 on a test called the Kapandji score, which measures thumb opposition, how well your thumb touches the other fingers.
- Grip strength returned to about 80–90% of that in their other hand.
- X-rays showed the implants were well-placed without loosening.
| Improvement Area | Result |
|---|---|
| Thumb opposition (Kapandji score) | 9/10 |
| Grip strength recovery | 80–90% |
Were there any problems?
Most patients healed well. There were only two small complications:
- One person had mild numbness in the thumb area, but it didn’t affect their function.
- Another person had a scaphoid fracture during the recovery period.
What questions do people ask about this?
- What does this surgery replace? It replaces surgeries that remove thumb bones or fuse them completely, which can limit movement.
- How long does recovery take? The study followed patients for an average of 16 months, but most healing happens in the first few months.
- Can this prosthesis fail? Yes, but the good news is that other surgeries like thumb fusions are still possible if it doesn’t work.
- Does it hurt? Every surgery can cause temporary discomfort, but long-term pain was reduced for these patients.
What is the bottom line?
Thumb pain can be frustrating and limit daily activities. This new prosthesis offers hope for patients who need another option after unsuccessful surgeries. Talk to your doctor about whether this treatment might work for you.
If you’d like to learn more about rhizarthrosis and treatments, keep exploring this site. Simplifying science for thumb health is what we do!
Is this medical advice?
This blog post is for educational purposes only and does not replace medical advice. Always speak with your healthcare provider for personal recommendations or treatments.
What is the cited article?
Glaser, J.; Aman, M.; Krohn, T.; Duerinckx, J.; Panzram, B.; Harhaus, L., 2025.
Scapho-metacarpal dual mobility prosthesis for TMC-1 joint salvage: technical insights.