Saturday, February 2, 2013

With Knee Pain, What We Believe Influences How We Interpret What We See

This is a famous drawing:

What do you see?

Do you see the dainty, pert-nosed young beauty, her head turned away? Or the large-featured old hag?

If you see the young woman, and your friend sees the hag instead, your first reaction may be to scoff and say, “No way! Look again!”

Now, suppose you are studying cartilage defects in human knees and learn the following set of facts:

* Between 34 and 62 percent of people having knee surgery are found to have cartilage defects.

* Some 50 percent of athletes (from recreational to professional) who have cartilage defects don’t have knee pain.

* The vast majority of people with moderate knee osteoarthritis don’t have functional limitations.

What would you conclude?

Colin Hoobler, a physical therapist, connects the dots thusly in this Q&A:

“... it’s entirely possible that your knee pain isn’t caused by your cartilage defects, but something else (muscle weakness, inflexibility and/or lack of coordination).”

(A quick aside: the “lack of coordination” explanation for knee pain I find a bit odd; I’ve never encountered it before and it seems to make sense mainly if this lack of coordination causes you to fall on your knees a lot. :))

Now, if you remember back to last week, you’ll realize that on the matrix for knee pain treatment and beliefs, Mr. Hoobler probably belongs in the upper right corner (among those recommending treatment that is “Not Joint Focused”). He will work on addressing your muscle weakness, tightness and general klutziness.

That’s because, when presented with the group of facts above, he sees one picture. But might there be another picture here, if we look again?


It might be described like this:

“It’s entirely possible that your knee pain is caused by your cartilage defects, but you don’t have to get rid of them to become pain-free, as they’re actually quite common and don’t always cause problems.”

This is great news! This belief (that I didn’t have to restore my cartilage to a pristine state) sustained me during a long recovery from knee pain.

In fact, this was my thought process as I embarked on the journey:

“An MRI shows I have “mild” chondromalacia, but my knees are really crunchy and always inflamed. Any MRI is imperfect*, so maybe it hasn’t detected what’s really wrong with the cartilage (after all, chondromalacia starts with damage deep within the tissue). I’m betting the problem is with my cartilage. I can either despair -- oh no, it’s damaged and will never be perfect again -- or I can take solace in the fact that lots of people are walking around with defects and feel fine. I just have to strengthen the tissue slowly (and hopefully it will heal along the way, as it’s done in various studies). Yeah! I can do this!”

But why would some defects be painful while others aren’t? Recall that cartilage has no nerves. Hugely significant. So the tissue itself isn’t sending out pain signals, but rather nearby structures are. Pain may result when the cartilage becomes too thin or too soft or too ragged -- but it won’t be a problem with all lesions.

So when you look at your bad knees, what picture do you see?

* Serendipity! As I was writing this, along came this brief article saying that MRI exams underestimated the size of cartilage defects by 70 percent (compared with what surgeons actually found during an arthroscopy), according to one study. So that MRI that suggests you have a small problem, or no problem at all, may not be trustworthy.


  1. Hi Richard, thank you for the post.

    Replying about the brief article you mention which states MRI's underestimate cartilage defects by 70%. Unless I'm interpreting their wording wrong, 1cm^2/3cm^2=30%, not the huge 70% they're quoting. Also, it could be that within the up-to-one-year between the MRI and arthroscopy that the defect actually did grow 30%? Although 30% doesn't seem all that significantly and statistically different to me...takeaway should be MRI's still identified the detects which makes them a very useful tool.

    Along these same lines, and as I've stated in previous posts, I believe you should still follow up with an MRI since you've healed, and compare that to your pre-healed MRI result. It won't change the fact you healed your knees, but it would be great to see if it correlates to your theories. I feel you kindly owe us all this.

    BTW, my defect size is around 0.5cm^2 as estimated by MRI. I definitely plan on following up with a subsequent MRI if my knee continues to heal with biking to work.

    Thank you very much. Do appreciate this blog and your book so much...please don't interpret my post another way. I believe reading your book is the number one reason my knee is improving.

    Thx, -Erik

    1. Glad your knee continues to improve!

      On the 70% figure -- I went back to the original abstract and it makes the same claim, that the MRI's underestimated defects by 70%. I agree that 30% (or actually more like 35%) appears correct, but there must be another piece of the calculation we're not seeing. Also, yes, MRI's are quite useful -- my point is just that they are limited.

      On a follow-up MRI for my knees, if anyone wants to donate an expensive MRI, I'd do it. However, I don't think it'd be that worthwhile because (1) My MRI was taken a few months before the worst of my knee pain (which came after my disastrous weightlifting), so I don't think it captured the worst state of my knees (2) I only had "mild" chondromalacia on the MRI anyway, not any large cartilage defects. I wouldn't be surprised if a new MRI showed about the same, even though my knees feel 20 times better (and I think the cartilage is about 20 times healthier).

      If I had had large defects, an MRI would be much more interesting. I'd be very curious about what an MRI shows on your knee in another year or two, if you continue the easy cycling. If you do one, please let me know!

  2. Just a note to say that I purchased the Kindle book today...and today is the first time I have felt some hope re: recovery since receiving the chondromalacia diagnosis back in 2005. (Which ended my military career.) Thank you for all of your hard work. I'll keep reading! It's refreshing to 1.) finally feel some optimism, 2.) get some "why" answers, & 3.) to have some ideas re: how to chart a course towards improvement amongst this...often confusing & discouraging journey through knee pain! ~ Molly in Michigan

    1. Thanks for checking in, and please let me know how you progress. I think optimism is very, very important, as the recovery is unfortunately long (but possible!).

  3. I've just found your blog & tonight will order your book.

    This blog is a revelation & has given me new hope after being on the dumb medical PFS round-a-bout for 10 months.

    My story is so similar to yours, it is amazing. I've been doing triathlons for 20+ years, long course triathlons the last 5, how the Hell could my quads be weak - I ride up to 250kms per week for Christ sake!

    In April, my L medial meniscus tore badly on a little run, had to have a chunk removed because it was catching & damaging the femur cartilage. From there, both knees went downhill with identical symptoms to yours - aching/stiff/burning/prickling knees, sore sitting at work etc etc.

    MRIs showed 'high grade chondromalacia' in R knee, and a little in the left. Physios went for all the usual crap you mention, plus fix hips/glutes. Sports Drs wanted to do surgery - drill holes in back of kneecaps, platelette injections/lateral release of ITB because kneecaps had a lateral tilt.

    Thankfully, alarm bells were ringing & I did not want more surgery (and my original OS who did the meniscus agreed more surgery was not the answer). So I started my search for a more conservative approach, and ended up here thankfully! Now I have some clues to follow.

  4. Thank you for your blog. I stumbled onto it when I had nowhere else to turn. After reading it a few hours I started riding my exercise bicycle a half hour a day. (no load, effortless pedaling. A couple days after I started I was walking at work and I was perplexed. My knees felt supergreased. Then I remembered what you said about NEW KNEES. I try to be more careful with them now so they can heal.

    1. Healing is definitely a long process, but it sounds like you are starting out very smart with the no load, effortless pedaling. Keep me updated on how that's going, cheers.