#9 – Can your quadriceps save your knee from arthritis?

Why does everyone think quadriceps strength will stop knee pain? Find out how this idea got popular and why the strategy can so often fail.


Analysis of the discordance between radiographic changes and knee pain in osteoarthritis of the knee.


Hi, everybody this is Matt Hsu from Upright Health, and welcome back to the Upright Health Podcast. We are now on Episode 9. So way, way back in Episode 6, we talked about osteoarthritis at the knee and I asked the question, “Can you really actually have arthritis on the knee?” And we looked at a study that talked about diagnosing osteoarthritis from X-rays and how the X-ray diagnosis of arthritis actually has no correlation to pain and symptoms — loss of range in motion, functional capacity being impaired. And so I came to the conclusion — and hopefully you also started coming to the conclusion — that maybe this whole idea doesn’t make that much sense.

Now, some of you may have knee pain yourselves or you may know other people who have had knee pain. And you may have gone to physical therapy and had your quadriceps focused on like nothing else. You had a physical therapist tell you, “You know what, knee pain? No problem. You just got to strengthen up your quadriceps group. You just need to straighten up your Vastus Medialis Oblique or VMO. No problem. Knee pain? No problem. We know what that is. We just work on the strength of your knee. If you have arthritis on your knee, no problem. We’re just going to make your quadriceps stronger.”

And if you’ve gone that route, you’ve probably noticed that it doesn’t work. You probably noticed that if it made it better, you’re lucky. And if It made it worse, you’re the type of person that I’ve seen a ton of times. And it makes sense when you look at it from a zoomed out view. So one should ask a question, “How did this idea of quadriceps strength gets so popular in terms of trying to treat knee pain?”

I have wondered it a lot myself, and so I did a little bit of digging. And I came up with this study done 1993 in the Annals of the Rheumatic Diseases. It’s Volume 52, Issue 4. 1993, Pages 258-262. The title of this study is “Determinants of Disability in Osteoarthritis of the Knee.” And so the idea of this study was, “To evaluate the influences of radiographic severity, quadriceps strength, knee pain, age, and gender on functional ability in patients with osteoarthritis of the knee.”

And so what they did is they were in English, there were basically looking at X-rays, quadriceps strength and whether this person had knee pain, whether age seemed to have any difference and whether gender seemed to play any role in the pain. Equal numbers of knee pain positive and negative respondents to a survey of registrants, aged more than 55 years, at a general practice were invited to attend for knee radiographs and quadriceps femoris isometric strength estimations. They also measured disability by using the Stanford Health Assessment Questionnaire.

And so basically, they are taking a bunch of people who are over 55 years of age who had knee pain or didn’t have knee pain and said, “Please come here. Let us take X-rays of your knee and test your quadriceps for strength in an isometric strength exercise.” Which by the way, I would submit is probably not a very functional test, but whatever, that’s how they did the study. Most of us don’t need to do an isometric quadriceps contraction for that long. Anyway, so they had 70 men, 89 women. Average age of the men was 72.7. Average age of the women was 68. 44% had knee pain. 48% had x-ray features of osteoarthritis. And 32% had some degree of disability.

So here’s the kicker if in fact the X-rays are useful in diagnosing arthritis, we should see a correlation between the radiographic score and knee pain. What they found was the radiographic score had no influence at all. So it appeared that the X-rays, it really didn’t matter what the X-rays look like. But what did matter was quadriceps strengths.

So what they stated in their conclusions was “Quadriceps strength, knee pain, and age are more important determinants of functional impairment in elderly subjects than the severity of knee osteoarthritis as assessed radiographically.” There is an implied therefore here. “Strategies designed to optimize muscle strength may have the potential to reduce a vast burden of disability, dependency, and cost.”

So, what they’re arguing is if you look at the muscles instead of the X-rays, you will probably get a better functional result. You’re going to be able to improve this person in front of you, if you’re a patient. If it’s somebody like me, it’s my client, it’s somebody I’m just training to (1) stop thinking of themselves as a patient; (2) think of themselves as a capable human being again. But when you’re dealing with this person, if you’re going to help them, you’re going to help them much more by dealing with the muscles rather than paying attention to what you see in that X-ray – which is great. I completely agree. But now, let’s think about what’s happened.

Now, you had another study that says the X-rays don’t matter, and the quadriceps strength seems to matter more. Does it logically follow that quadriceps strength only is that the thing you need to focus on to help somebody who has a limited functional ability with knee flection and extension? If you are zooming out and looking at the way the human body moves, it would make absolutely zero sense to think that strengthening only one muscle group is going to change everything for the better.

Now, don’t get me wrong. I think this is definitely something that goes in the right direction, but we don’t all need to have super strong quadriceps, and then have super weak back sides. I think there’s definitely something to it. Having a quadriceps group that is capable of supporting your weight and contracting and then extending the knee joint, I think that is certainly important. But those are not the only muscles that determine whether or not you can get up out of a chair. Those are not the only muscles that determine whether you are comfortable walking for more than fifty feet. There are many other muscles, and I’ve mentioned them before. And we’ve all heard of them – the gluts, the hamstrings, Gluteus Medius Maximus, the deep hip rotators are very important. What your Adductors are doing are also important.

It makes no sense to simply say, “Well, we measured the quadriceps, so the quadriceps are the only thing that matter.” But that seems to be what has happened. So this is a case, I believe of pretty strong tunnel vision and not recognizing the limitations of what was being measured. There are a lot of variables with the human body. And it goes without saying that there are a number of factors that go into every aspect of health. Especially with the muscular skeletal system. It really doesn’t make sense to think that if you just measured and addressed one group of muscles, that you would magically fix symptom X or symptom Y. It really is about looking at what the body is capable of doing. How everything is working together to make sure that a minimum of strain is being focused into one spot.

So if you know somebody who has knee pain and who has gone through physical therapy, who has done all the work on the quadriceps and was frustrated, or you are that person; if you know somebody who’s done that, I want you to share this with them. And if you are that person, you’re already here, so I’m glad you’re listening. Realize that the research that has been done to date on how to deal with knee pain is very limited at best. There are all kinds of different studies.

I realize what I’m sharing with you was done in 1993, but I’m sure you’ve noticed treatment strategies have not changed that much. But the research that underpins a lot of what is done, is really limited and is really subjected to this tunnel vision that really limits the amount of progress that you can really make. So this is why I always come back to the idea of setting a very high goal for yourself and then working gradually towards that goal.

I should actually share this idea that one of my clients shared with me yesterday, actually. It’s completely in line with what I believe. And what he said was… he rides a motorcycle out in the mountains. He’s a dirt biker. And he said, “You know, when you’re riding your motorcycle or riding you dirt bike, you look ahead to where you want to go. The biggest problem is when you get a new rider who is afraid of running off the cliff and he keeps staring at the edge, and naturally then naturally drives towards it. The trick is to keep your eyes on the path ahead and keep focused on what you’re going to do to get to the next spot.”

So I thought I’d share that with you. I hope it helps you. And I hope that you remember that pain sucks – life shouldn’t.


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