Osteoarthritis, and a Post-Industrial Era Mystery

The latest issue of Harvard Magazine looks at a curious mystery.

Two biology researchers from Harvard University discovered the mystery after visiting medical institutes across the country and examining skeletons over the centuries.

They were searching for evidence of knee osteoarthritis (bone-on-bone rubbing in places where the cartilage has completely eroded, which leads to polished bone surfaces that are a telltale sign of the disease).

When they compared the skeletons from the prehistoric and industrial eras to those from the postindustrial, they found that the prevalence of knee OA has more than doubled since World War II.

You might think: Sure, of course it’s higher. People live longer. More people today are obese.

But controlling for age and body mass index didn’t make the difference go away. To be sure, obesity contributes hugely to knee OA. But it wasn’t causing the spike in cases.

The researchers still aren’t sure what’s going on, but they’re testing a hypothesis that I think will yield their answer.

Physical inactivity, they speculate, may be what’s to blame. The mid-twentieth-century shift to service-sector jobs put more people in workplaces where they got less movement. The modern desk rat was born.

We sit, and sit, and sit, and sit, and then wonder one day why our knees hurt.

Because our knees weren’t designed to do nothing at all for long stretches?

Or, as the article says, in more prolix language: there’s a “suspicion that OA is a case of human physiology being partly maladaptive to modern environments.”

Healthy, joint-nourishing motion IS important.

This, I believe, is the key to preventing knee pain, or once you have it, recovering your pain-free knees once again.