If thumb pain or arthritis is bothering you, you’re not alone. A recent study looked at 104 hands from people who donated their bodies to science, and the researchers discovered some fascinating information about how the tendons of a muscle in your thumb, called the abductor pollicis longus (APL), attach to different places in the hand.
Here are a few key findings:
- Almost everyone has several tendons from the APL muscle going to different places in their thumb.
- One of those tendons always attaches to the base of the thumb bone, while others often connect to nearby areas like the wrist bone called trapezium.
- Arthritis at the base of the thumb was incredibly common, with 97% of the hands studied showing signs of it!
All these details were studied to explore if there’s any link between how the tendons attach and the severe arthritis many people experience. In this article, we’ll take a closer look at what the study uncovered and what it might mean for you.
In this article
- What is the abductor pollicis longus?
- How do its tendons attach?
- Does this cause thumb arthritis?
- FAQ
- Conclusion
- Disclaimer
What is the abductor pollicis longus?
The abductor pollicis longus (APL) is a fancy name for a muscle in your forearm. It helps move your thumb away from your hand, which is important for gripping, holding, and reaching. To work, it uses tendons—cord-like tissues that connect muscles to bones and pull on the bones to create movement.
How do its tendons attach?
Here’s where it gets interesting. This study discovered that for most people (95% of cases studied), the APL muscle doesn’t just have one tendon. It splits into multiple tendons, which attach to different spots in your hand and wrist.
For everyone studied, there was always one tendon attached to the base of the first metacarpal bone, which is part of your thumb. In 70% of cases, there was also a tendon going to the trapezium. The trapezium is a small wrist bone that forms part of the joint at the thumb’s base. Additionally, 42% of people had an extra tendon attaching to the fleshy part of the hand under the thumb, known as the thenar eminence.
| Insertion Location | Percentage of Cases |
|---|---|
| Base of thumb bone (first metacarpal) | 100% |
| Wrist bone (trapezium) | 70% |
| Fleshy part under thumb (thenar eminence) | 42% |
Does this cause thumb arthritis?
You may be wondering why this matters. The researchers wanted to see if there’s any connection between these tendon arrangements and arthritis in the first carpometacarpal (CMC) joint. This joint is where the base of your thumb meets your wrist, and it’s a common place for arthritis.
Here’s what they found:
- An astounding 97% of the hands studied showed arthritis in this joint. In most cases, the outer (lateral) part of the joint was the first to be affected.
- However, there was no clear link between severe arthritis and how the tendons of the APL muscle attach.
This means that while thumb arthritis is very common, it doesn’t seem to be caused by the specific way the tendons are arranged.
The researchers even explored whether cutting some of these tendons early on might prevent arthritis from developing. But based on their findings, early surgery to cut tendons cannot be recommended.
FAQ
- Q: What is rhizarthrosis?
- A: Rhizarthrosis is another name for arthritis affecting the base of your thumb. It can make the joint painful and stiff.
- Q: How might I know if I have arthritis in my thumb?
- A: You may feel pain at the base of your thumb, have trouble gripping objects, or notice swelling in the area.
- Q: Can thumb arthritis be prevented?
- A: This study suggests that tendon arrangement doesn’t seem to cause arthritis, so preventative surgery isn’t advisable. Exercise and proper care may help ease symptoms.
Conclusion
To sum it up: arthritis at the base of the thumb is very common, but it doesn’t appear to be linked to how the tendons of the abductor pollicis longus attach. While it might be tempting to look for surgical solutions, based on this study, early tendon surgeries are not recommended.
If thumb pain is impacting your life, speak with your doctor or hand surgeon about other ways to manage symptoms. Exercises, braces, and other treatments might help you feel better.
Disclaimer
This article is for informational purposes only and is not medical advice. Always talk to your doctor for professional guidance on your health.
Article Citation
Bouchlis, G.; Bhatia, A.; Asfazadourian, H.; Touam, C.; Vacher, C.; Oberlin, C., 1997. Available at: https://www.ncbi.nlm.nih.gov/pubmed/9479442