Is there any explanation for why some of our family members develop osteoarthritis and others don't? My 56-year-old sister has terrible arthritis of the hand while our 90-year old grandmother does not. I don't have it either and I'm older (62), but there are some cousins on my father's side who all seem to have some sort of arthritis.
We may not have a simple, direct answer to that question. As it turns out, osteoarthritis is a fairly complex disease and one that is not very well understood. Taking a look at risk factors may shed some light on the subject.
Let's take the most obvious: overuse of the hands. You might think the way people use their hands at their jobs would make a difference. But researchers have not been able to clearly establish a link between occupation and arthritis. Cotton-pickers and industrial workers are at a disadvantage and are more likely to develop hand arthritis. But that's as far as the evidence goes.
Okay, so what about age? Are we agreed that the older you get, the more likely it is you will develop arthritis? Well, yes, in a way age is related because the majority of people who have osteoarthritis of the hands are older (over 55). But as you pointed out, what about all the older folks who don't have arthritis? There are plenty of adults up into their 80s and 90s who are arthritis-free (including your grandmother). How do we explain that?
Genetics. It seems the most recent scientific research has been able to put a finger on the contribution of genetics as a potential risk factor. Gene mutations have been identified that when present may explain the higher incidence of hand arthritis in some, but not all, people.
Hormones seem to play a role here, too. Postmenopausal women are more likely to see their arthritis get worse despite treatment. But even this risk factor is inconsistent because only certain joints (for example, the base of the thumb) are affected. If low estrogen levels are linked with arthritis, then why aren't all the joints involved? Scientists are still scratching their heads over that one -- they simply don't know.
Racial/ethnic background and hand dominance are two final risk factors under investigation. So far, it looks like there may be something here as both being Caucasian (white) and favoring one hand over the other for most activities may lead to a greater risk of developing finger arthritis. Using one hand more than the other and ending up with arthritis is probably due to the added biomechanical load on the joints.
Why Caucasian Americans have much more hand arthritis of the proximal interphalangeal (PIP) joints compared with Chinese people is unknown. There may be genetic, lifestyle, joint mechanics, or other protective factors in the Chinese group that have not yet been identified.
It's likely that there are some specific factors (more than one) that interact with each other in such a way that the final outcome is joint arthritis. Knowing how important the hand is for daily activities, especially self-care (grooming, toileting, preparing and eating food), research needs to continue placing an emphasis on unraveling the mysteries of this disease.
There are many avenues to explore from genetics to types of arthritis, risk factors, and joint changes. Prevention may eventually be possible and when that isn't successful, then finding treatment techniques that work is next.
Benjamin J. Jacobs, MD, et al. Proximal Interphalangeal Joint Arthritis. In The Journal of Hand Surgery. December 2010. Vol. 35A. No. 12.
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