Friday, February 25, 2011

A Scientific Investigation: What Effect Does Physical Activity Have on Knee Joints?

After last week's ultra-long post, I'm going to go short this week.

So today, without a lot of elaboration, we'll look at the latest scientific roundup on how activity affects knee joints.

An article on exactly that subject (just released online) is slated for March publication in the journal Medicine and Science in Sports and Exercise. What's more, it's a systematic review -- double gold in my eyes, because a systematic review aims to synthesize the evidence from a pile of existing studies.

Such a method reaches a more certain truth because, as we all know, individual studies can be confusing, as they sometimes contradict each other.

The article's researchers, led by Donna Urquhart, examined a total of 28 studies. Here are their conclusions (with my comments afterward). I've ordered the list from least to most interesting to build up a little suspense.

(1) There is limited evidence that there is a positive relationship between cartilage volume and physical activity.

Good news! And not surprising! (I suspect future studies will supply even more evidence). So this means people who are physically active have more cartilage in their joints than their lazier brethren.

(2) There is strong evidence that there is no relationship between joint space narrowing and physical activity.

At last, it's time to shut up the "tut tut" birds. You know the ones: they look at you askance and warn that with advancing age, running/cycling/playing basketball will just hasten the inevitable breakdown of your knee joints. For example, running will lead to deteriorating cartilage, and that means eventually the bones will be brought into closer proximity (joint space narrowing), until you're in danger of having bone scrape painfully on bone ...

Great Halloween horror story. But not necessarily true, it appears.

(3) There is strong evidence that there is an inverse relationship between cartilage defects and physical activity.

Hooray! In other words, the physically active have fewer cartilage defects. I'll go even further and predict what a systematic review may find in another 10 years or so: not only do physically active people have fewer defects, but more of those defects will be shown to improve over time than among the general population.

(4) There is strong evidence that there is a positive relationship between osteophytes and physical activity.

Okay, this is the one that should have surprised me greatly, except I had read this New York Times piece a while back. Osteophytes (or bone spurs) don't have to be bad; they can be of the good "protective" variety, it turns out. Spurs are sometimes just a way the knee adapts to the forces pulling on the joint. "There is ... evidence to suggest that osteophytes can develop without explicit injury to cartilage," according to this latest article.

Yet more good news ...

Time to get active!


  1. Hello,

    I have a question about your book and whether it would be a good purchase for me. I was diagnosed with chondromalacia (both knees) about 20 years ago and told to strengthen my quads. My knees gradually calmed down and I was mostly comfortable until a recent and unexpected flare-up in Nov., following development of a Baker's cyst, which I'd never had before. I've still got the cyst, but my OS said to not worry about it, but rather, to pay attention to pain signals from my knee.

    Now, at age 55, I've been diagnosed with osteoarthritis (both knees) showing up mostly in the PF compartments with some areas of full-thickness cartilage loss in the right knee. My OS indicated joint replacement might be in my future, but to stay active and put that off as long as possible. I got sent to PT and have been dutiful and sometimes skeptical. Motivation is not a problem, but I want to invest my efforts, time and money where they're more likely to pay off.

    Given my OA diagnosis, am I "too far gone" for you book, which seems to be geared toward PFPS, rather than OA, per se? If there's a good way to rehab the insides of my knees, I'd sure like to know. Thanks very much for your thoughts.

  2. I forgot to specify where the cartilage loss and damage are--both patellas, with the areas of full thickness loss on the right patella, the poor thing. Thank you.

  3. Hi, Patricia, and welcome. I don't consider anyone "too far gone" (though the worse your knees, the greater the challenge in your recovery, obviously). True, I didn't have osteoarthritis (though I was heading in that direction). Still, what I learned about healing bad knees I think applies to a wide range of problem joints. My book is my story -- how I got better even when I was told I couldn't -- and so provides some inspiration, I hope, along with a framework for understanding what bad knees need to heal. This framework is so, so important, I think. Can full thickness defects of cartilage heal? Certainly, but it can be a challenge. I would consider (1) losing weight (2) finding a nice, gentle, high-repetition activity that my knees tolerate well (cycling backwards, if necessary) and (3) modifying my daily lifestyle as is needed (maybe lessen sitting, no more floor-scrubbing on my knees -- whatever). Good luck!

  4. Thank you for your response and recommendations, Richard. Will your book become available in a format compatible with Barnes & Noble's Nook? If not, I'll read it on my PC, since the format conversion methods I've found are a hassle, but I prefer using the Nook when I can easily do so.

    I hope you and your knees are doing great. Your story is an inspiring one.

  5. Wanting to read your book on my BN Nook inspired me to research again the available means of conversion from Amazon's MOBI/.azw format to BN's ePub, and I found a much easier way to accomplish this. In case anyone else asks you if you're going to make your book available in formats other than Kindle's MOBI/.azw, a description of the easier conversion method I found is here:

    This conversion is no doubt a technical illegality, but if one has purchased a book through legitimate channels, it's certainly not unethical. I purchased your book and am about 25% of the way through it. Having worked as a technical editor, I appreciate not only the clarity and readability of your writing, but also its lack of errors, the presence of which can so undermine an author's credibility.

  6. Good question about the Nook -- I have been asked that before. The answer is I am edging toward Nook-compatibility and hope to be there in say a month or two ... unfortunately I'm a man of many projects :) and this is about #3 on my list right now (partly because my research shows that 90% of e-readers are buying through Kindle, with Nook and others a distant second). Cheers!