Arthritis spares flexible fingers

People with unusually flexible fingers seem to be able to give the slip to osteoarthritis in the hand, new research suggests.

The study of 1,043 men and women found that the 4 percent with "hypermobile" joints - commonly called double-jointedness - were two-thirds less likely than their less flexible peers to have arthritis in the middle joint of the finger.

A similar benefit was seen among adults whose joints were highly flexible in their youth but had since grown rusty, according to findings published in the journal Arthritis & Rheumatism.

All of the study participants were at risk of extensive hand arthritis because all had a family history of the condition and each had shown X-ray evidence of arthritis in the joint near the fingertip.

The results are somewhat surprising since joint hypermobility has been suspected of raising the risk of osteoarthritis, the form of arthritis associated with aging and caused by wear and tear of the joints.

One study has linked extreme joint flexibility to a higher risk of knee arthritis. It's thought that excessive range of motion in a joint may put abnormal stress on it, as well as raise the risk of injury - both of which may predispose a person to arthritis.

But in this study, flexibility - and limber fingers, in particular - appeared to be an asset.

The researchers, led by Dr. Virginia B. Kraus of Duke University Medical Center in Durham, North Carolina, assessed hypermobility with a series of standard tests. Two of the tests looked at how far backward the little finger and thumb could bend. An analysis of a sub-group of the participants showed that all who were deemed hypermobile owed the label, in part, to highly bendable digits.

A previous study found that joint hypermobility appeared to protect against arthritis in musicians who need nimble fingers, such as flutists and string musicians.

The current findings, Kraus and her colleagues conclude, suggest that extreme joint mobility may stave off hand arthritis even in people who are genetically predisposed.

According to the researchers, a person's grip strength may sway the risk of developing arthritis in the fingers, and research suggests that hypermobile people tend to have lesser grip strength. It's possible, they suggest, that hypermobility alters joint stress produced during gripping or pinching motions.

SOURCE: Arthritis & Rheumatism, July 2004.