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Video:Causes of Thumb Arthritis

with Dr. Nader Paksima

Thumb arthritis is a common ailment and is often caused by the severe stress put on the thumb every day. Learn more about the causes of thumb arthritis.See Transcript

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Transcript:Causes of Thumb Arthritis

Hi I'm Dr. Nader Paksima, orthopedic hand surgeon at the NYU Langone Medical Center for About.com. In this video, I will be discussing about why the thumb joints are particularly prone to damage.

What Is the Thumb Joint?

The thumb is the most important digit of our hand and we ask it to do a lot. Most joints in the body move in one direction. For example, look at that joint right there. That joint only moves in an up and down direction. But the base of the thumb, we ask it to go up and down, side to side, and also to rotate. So a tremendous amount of motion goes through that joint.

Overview of Causes of Thumb Arthritis

Arthritis occurs when the cartilage wears off of a joint. So why does the thumb arthritis occur? When you look at the joint of the thumb, it's basically shaped like two saddles sitting on top of each other. They go forward and backwards, side to side, and they also rotate. So a tremendous amount of forces go through these joints.

Severe Stress on Joint Can Cause Thumb Arthritis

Because of the bio-mechanical forces, the way the muscles and tendons are attached to your thumb, the forces that you generate at your finger tips when you pinch are multiplied by 12 times the force at the base of your thumb. A typical person will have the pinch strength of 10 to 20 pounds. If it's a 20 pound pinch, 240 pounds of stress are going through the basal joint of your thumb. So that joint can easily see forces that are greater than your body weight.

Compare Thumb Joint to Shoulder Joint

We use the thumb for every singe thing so throughout the day stresses are going through that tiny little joint. Compare the thumb basal joint to the shoulder joint, a joint that is very resistant to arthritis. The shoulder joint has a tremendous amount of motion but it is a large joint. It's basically shaped like a basketball sitting on a dinner plate. So those forces are spread all around into different areas and one part of the cartilage doesn't see all of the wear and tear. Whereas in the thumb, all of those forces are concentrated into a tiny little area. So significantly more pressure goes through it.

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