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Is there any truth to the idea that being overweight is linked with thumb arthritis? I have both and I've been told there's a connection. What is it?

Scientists from Finland have reported a direct link between increased body mass index (BMI) and arthritis of the thumb. Specifically, carpometacarpal (CMC) arthritis was identified. The CMC is located at the base of the thumb as it connects to the wrist.

There are at least two possible reasons for the observed link. First, people with a higher BMI have increased mechanical load on this joint. This is true even though the joint is not a true weight-bearing joint. Any amount of increased load across a joint can cause increased wear and joint destruction.

Second, there may be a biochemical reason for obesity being linked to CMC arthritis. It's likely that changes in chemicals associated with obesity affect the joint. There are differences in the levels of lipids (fats), insulin-like growth factor, and sex hormones in patients with a higher BMI. Biochemical changes of this type may promote early joint degeneration.

Trauma, altered biomechanics, and anatomical differences may be risk factors, too. More studies are needed to find out the exact cause and effect for this condition. It may be multifactorial (many causes) but if any risk factors can be changed, then it may be possible to prevent this painful problem from occurring.

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