Anthropology of Knee Osteoarthritis

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By: Dr. Jill Murphy

deep squat positionSometimes in healthcare and life we just walk on through our day and never sit and ponder the reason why things have come into being. For instance, why do toddlers and preschoolers have the best squat form in the world, will play in this perfect squat position for hours, only to lose this perfect body mechanics the minute their rear end hits the chair once they start attending school every day?

The same deep thoughts can go for knee osteoarthritis. Did our ancestors knees, hips, and shoulders wear out? Of course, the technology to replace these joints has just come about now. But what happened in the days and times before fusions and joint replacements? Well, the short answer, is the body fixes itself by self-fusing. This is the process of losing cartilage, the bony ends of the joint grow together, and boom, no more pain, because your joint is no longer moving!

While this is one approach, in our modern day society, we skip the years or decades of pain, stiffness, and limping, we just go ahead and visit our orthopedist or neurosurgeon and we get the work done. Especially in this era of slim to no pain control options for the long term, even the possibility of toughing it out is pretty much over.

But the truth is, hundreds of years ago when Americans spent all day farming, milking cows, gardening and hunting for food sources, their knees didn’t wear out! Why? Because no one sat down until all the work was done- dinner time or well after dinner is what I reveal from the Little House on the Prairie episodes. Maybe only in winter would you sit a bit more, because of the blizzard billowing outside, limiting chores to feeding and maintaining the animals, cooking, and cleaning.

Some facts to back this up? The prevalence of knee osteoarthritis is double what it was just 75 years ago according to researchers studying skeletons from as old as 1800. And we all know what has happened in the past 75 years- the industrial/technology revolution?! That thing that was supposed to save us all this time and improve our lives has resulted in sitting in once place to perform all of our work, from ordering our food in, to hiring our housecleaner, to ordering supplies we once shopped for, and everything is done from the comfort of our living room recliner or desk chair. And work? According to the New York Times, 80% of our jobs are now sedentary, a decline in more physical or manual jobs by 30% over the past 50 years, causing the new sit to stand stations now available to be THE hot new commodity for sedentary office workers!

The good news? Well, the prevalence of knee osteoarthritis overall in the research of subjects of our era (the post-industrial era) is 16% overall, meaning, it still may take a significant injury or poor genetics to force you to schedule a knee replacement surgery at some point in your lifetime. More good news or maybe neutral news, body mass index did not seem to increase the risk of knee wear and tear; however, this was difficult for researchers to accurately measure on skeletons from prehistoric samples. On the flip side, if you have it in one knee, you are likely to have it in the other as well, as bilateral knee osteoarthritis is evident in 42% of those of us in our era, whereas both knees had OA in 30% of early industrial era samples, and only 17% in the prehistoric group.

So what’s the takeaway? Get off your duff! Physical activity participation on a daily basis may be able to mitigate our eight hours or more of sitting on the job. Go ahead and utilize that sit to stand station, and maybe event the treadmill station (or just take a walk during lunch!). While body mass index was a low-level player in this study, we know we are overall healthier with reduced risk of hypertension, diabetes, and heart disease if we keep our body mass down. Finally, don’t wait forever to treat your knee pain! There are so many successful treatments we can do in physical therapy and ways to teach you how to move in a mechanically better way to reduce the wear and tear on your knees to prevent or delay the onset of knee osteoarthritis. If ice and rest along is not doing the trick, don’t let your knee pain limit your overall activities! Address it today to reduce your risk of surgery this year or in the next thirty years with physical therapy!