Medical Studies About Bad Knees: Approach With Caution

Recently I came across an essay by an accomplished doctor about knee pain. I read through it with interest. Toward the end, he noted this Mayo Clinic study as evidence that strong quadriceps muscles prevent knee cartilage from deteriorating.

Now, let me get something out of the way: I do believe that having strong quads is helpful for knee pain sufferers. So what follows is written partly in a spirit of mischievous contrariness. But that’s okay, because today’s message is really about how to evaluate medical findings.

First, did you take a look at the abstract I linked to? Go ahead. I’ll wait. ;)

Now, with regard to preventing knee cartilage loss, what’s worth noting about this study?

The claim is very modest.

Let’s look at that section of the conclusion:

Greater quadriceps strength had no influence on cartilage loss at the tibiofemoral joint, including in malaligned knees. We report for the first time that greater quadriceps strength protected against cartilage loss at the lateral compartment of the patellofemoral joint, a finding that requires confirmation.

The claim isn’t that stronger quads protect against cartilage loss all across the knee joint. Or even that they protect against loss all across the patellofemoral part (where the femur and patella meet). Rather, benefits are restricted to the “lateral compartment” (the outer one, in other words) of the patellofemoral joint. And this finding “requires confirmation.”

At this point, I should backtrack a little: That’s really nothing to be alarmed about. Medical researchers write with an abundance of caution and interpret findings conservatively. That’s a good thing. Still, it shows the study didn’t prove that much (though, again, I do believe that quad strength does help protect joints and would expect the findings to be confirmed by other studies and perhaps expanded, in terms of the benefits).

The claim may not even be proven.

This is where I wish I had the full study to examine, but it’s behind a paywall. Oh well.

Anyway, consider what appears to be going on here, reduced to simple terms: An inverse correlation has been observed between two variables. When A (quad strength) is high, B (cartilage loss) is low.

So A inversely influences B.

Or does it?

Notice the assumption of cause and effect here: a higher A (quad strength) causes less B (cartilage loss). But what if cause and effect should be flipped around? Namely, more B contributes to less A?

Well, how would that work, you may be wondering. Consider this: The process of cartilage loss, especially in those with knee osteoarthritis (the members of this study), is generally inflammatory/painful, as fragments of cartilage migrate out to the nerve-rich synovium. So cartilage loss causes knee discomfort, knee discomfort discourages the sufferer from moving/exercising, and the inactivity leads to weaker quads.

Ergo, cartilage loss causes weaker quads! And so, by a little logic jiu jitsu, the conclusion is stood on its head.

Or consider another possibility: there is a larger force at work here, which causes both weaker quads and more cartilage loss. Let’s say it’s the disease process of osteoarthritis. Let’s suppose inflammatory factors associated with the disease cause more cartilage loss, and at the same time the pain of osteoarthritis results in less movement, and thus weaker quads.

In such a scenario, it wouldn’t make sense to speak of more A (strong quads) leading to less B (cartilage loss), or even the opposite, because they are both at the mercy of the intensity of the disease.

The claim isn't prescriptive.

A naive reader, after perusing this abstract, may conclude, “Oh, because I’ve got osteoarthritis, and strong quads protect against cartilage loss, I should build up my quads!” But the conclusion is observational (more A leads to less B), not prescriptive (if you have osteoarthritis, you need to exercise so that you’ll have more A).

In fact, that same point is basically made by this article that summarizes the study (my bold):

Although the study did not involve exercise training to strengthen the quadriceps, there have been several short-term studies that show that improving quadriceps strength has a beneficial effect on knee pain and function.

Ah, but you may be thinking, that even though the Mayo Clinic study doesn’t settle the issue, “there have been several short-term studies that show that improving quadriceps strength has a beneficial effect on knee pain and function.” So surely they settle it, right?

Maybe not. Because look at this line from the Mayo Clinic study:

While our findings suggest that maintaining strong quadriceps is of benefit to those with knee OA, further work is needed to determine the type and frequency of exercise regimen that will be both safe and effective.

This is the crux of the matter. Even if you’re convinced that strong quads protect weak knees, what’s the most effective way of gaining (or maintaining) quad strength when your knees hurt most of the time? What if, paradoxically, it’s better not to worry about quad strength for a while and strengthen your joints instead? For example, what if, in those studies showing improved quad strength benefiting knee pain and function, the subjects have a 60 percent success rate, while if they focused on improving joint strength (what I did), they might have a 90 percent success rate?

Some kind of exercise/motion is beneficial for bad knees, I’m pretty sure, but exactly what kind needs more rigorous scientific investigation. In the meantime, remember to read scientific studies carefully, and make sure you understand what is really being proven -- and what isn’t.

Comment Corner: Finding That Sweet Spot for Movement -- Not Too Much, Not Too Little

Letters, we get letters (well, comments):

I'm 44, weigh 119 lbs, and hurt my knees running marathons 6 yrs ago. Thank you so much for helping the rest of us! You've mentioned "pushing the envelope" and I'd like to know how to plan my recovery. Do you suggest increasing the # of steps by a certain amt/% each week? I feel lost in knowing what to do - I would like a plan. I wear a pedometer and it's showing my daily steps are around 10,000. That seems like a lot compared to what you've mentioned. I don't feel any better (I'm in discomfort all day) but also not worse - you've said that is ok, right? Or should I do less steps until I feel better and then increase my steps? How does one know how to "push the envelope" without causing further harm? Thanks!!! Theresa

This is a great comment because these are some of the best (and hardest) questions. I wish I could pluck simple, satisfying answers from the air (6,400, at least nine weeks but no more than 12, when it turns red but is not inflamed). Unfortunately, there is no magic formula.

(Usual disclaimer by the way: I'm not a doctor or trained medical professional, so naturally discuss the following with one).

Do you suggest increasing the # of steps by a certain amt/% each week?

No. In my opinion, that would be crazy.

That would be crazy because all knees are different and, what's more, a strict rule (or even a rule of thumb) doesn't allow for inevitable setbacks. You may be happily increasing your step count by 15 percent every four weeks, then boom! You go on an ill-advised hike, suffer a setback, and all of a sudden you're struggling just to maintain your normal daily program.

However, I would consider (a) starting a knee journal, to help figure out when it's appropriate to increase step counts (b) getting on a once-a-week planning schedule. I used to do a weekly entry in my knee journal where I jotted down my observations about what went right (and wrong) that week and laid out my plan (including step counts) for the upcoming 7 days.

I don't feel any better (I'm in discomfort all day) but also not worse - you've said that is ok, right?

It seems that may be okay. But that may not be okay. It depends.

If you've been doing 10,000 steps daily for a year, and you feel about the same, I'd tend to say, "That's not okay." You're not getting better.

If you've been doing 10,000 steps daily for a few weeks, with no improvement, but before that you were feeling worse each week, I'd tend to say, "That's probably okay." Hopefully, you're in a transition period to getting better.

Or should I do less steps until I feel better and then increase my steps?

It's hard to say, but I do believe that with healing bad knees, you have to err on the conservative side. I went really, really conservative at one point (just doing simple walkarounds at the pool) and was surprised how effective that was.

If, by nature, you're competitive, motivated and driven (as I was, and I suspect you are), I would modify that comment a little to: ERR ON THE CONSERVATIVE SIDE. That's because you're especially at risk of pushing too hard because of who you are.

How does one know how to "push the envelope" without causing further harm?

First, I think you have to think more in terms of "nudging" the envelope, if you will. Still, this is the hard crux of the matter. It returns us to that central puzzle: How many steps should you be taking, and how do you know when (and by how much) to increase them?

Here are my two best ideas:

Try to work with a smart physical therapist, who (hopefully) can measure the strength of your bad knee and help you design a program around what it's capable of doing. Someday, I predict, most physical therapists will do these measurements as a matter of course. Today, sadly, we're still in the semi-Dark Ages on chronic knee pain and how best to treat it.

However, Sports Center in Austin does this sort of "load" testing. If you can go there, I would.

Experiment. I spent a lot of time doing this. Experimenting does require a good ability to sniff out immediately when something isn't working and when it deserves to be given a few weeks or so before being abandoned.

Is 10,000 daily steps too much? Try 5,000 or 6,000 or 7,000 for a few weeks. Or try taking steps in smaller bunches. Or trying taking different kinds of steps. Or ...

The possibilities are constrained only by your imagination. Whatever you do though, document it carefully and smartly so you're constantly learning what works and what doesn't. Pretend you're a scientist. That's what I did, basically.

Yeah, no easy answers. Yeah, a lot of work (and patience) required. But if it was easy, no one would have bad knees, would they? :)

Some Thoughts on Moving Your Knees: How Much Is Enough?

The other day I got this comment from “An”:

I’m a 25 year old woman who has never been an athlete (to be sincere, just the opposite), but I’m determined to beat this knee pain as it’s keeping me apart from my life, my career, my friends and even daily life activities. I don’t have another option, anyway. It’s this pain or me. And it’s gonna be me, definitely.

I have some doubts about your healing program. Those short walks you did every ten minutes around your apartment… did you do them only the first month of your program (when you were not prepared to walk a lot) or did you keep doing them when you were building distance? Did you do them ALL day? Didn’t that irritate your knees?

Sorry for asking such personal and specific questions but I can’t walk as much as you did at the beginning of your plan. I can only walk less than a mile daily without pain, after many moths (I started with 200 metres per day), and sometimes I feel as if I wasn’t doing enough (type A way of thinking, I guess). I walk a few steps around my home every two hours or so.

First of all, not to worry -- that information isn’t what I consider personal (unlike, say, what color underwear I have on). Also, you may not be an athlete physically, An, but you appear to have some of the essential mental attributes. For one, you’re determined and focused on a goal: beating this condition!

To answer your questions: (1) As I recall, I did my “walkarounds” (which involved setting a timer to go off every 10 or 15 minutes, then taking 70 or so steps around my apartment) for the first few months of my recovery -- more in the beginning and less as my knees got stronger. By the six-month point, for example, I wasn’t really doing them, and was focusing on taking longer, more challenging walks. (2) Maybe I didn’t do them all day, but most of the day, yes. So you see: I’m very disciplined (and maybe a little crazy). Also, remember I had no job then. I had embarked on a one-year experiment to save my knees. Healing was my No. 1 focus, constantly. (3) Doing walkarounds didn’t irritate my knees. But if it bothers yours, then maybe you need to do them less frequently, or take fewer steps, or find some substitute activity.

So those are my answers.

But here’s the postscript, which you all can probably see coming.

Doing exactly what I did almost surely won’t be the right thing for your particular knees. Your knees may need to do some variety of walkarounds for a week, a month, a year -- or not at all. Maybe another activity suits them better. I liked walkarounds because they got me moving in short, manageable bursts and got me moving in an activity that was useful (in other words, my knees were making adaptations in order to walk more -- and walking is something we need to do all the time, as opposed to say leaning against a wall as if sitting in an invisible chair).

In my opinion, that’s the bigger picture (which I think An already recognizes). The really big picture requires stepping back and thinking about what walkarounds and other similar activities are meant to accomplish.

And sometimes it’s good to look at the really big picture.

I started doing walkarounds because (1) I knew motion was critical to healing bad knees (2) my bad knees thwarted my attempts to move as much as I wanted to (3) my knees responded well to short bursts of walking.

For me, these were the main ideas to keep in mind, as I fashioned a program to get moving.

Finally, to An: congratulations! You can now walk less than a mile a day without knee pain, up from 200 meters. I know what you’re thinking: Yeah, but that’s after many months! True, but you’re in the middle of a loooooong process. It’s hard to overemphasize, in fact, how long this type of healing takes.

The good news is, the stronger your knees get, the faster it goes (and the more tolerant your joints become of the mistakes you invariably will make along the way). That was my experience anyway.

Good luck!

Which Qualities Do You Need to Beat Knee Pain?

Recently I was pondering who my message about how to beat knee pain would benefit the most. Let’s face it: Different books (and messages) resonate with different types of people.

For example, there are those who are intensely curious about drugs that will mute their discomfort. For those people, Saving My Knees would probably be a waste of ten bucks. The more I learned about knee pain during my own recovery, the less impressed I was by what drugs could do for me. In fact, it became clear they could contribute to making my problem worse.

So there are people that the book and this blog aren’t suited for. Then there's my ideal audience. I have come to the conclusion that that’s “athletes” -- but not for the reasons you probably think. (I’ll return to those quote marks later.)

First, here’s why I bet you think I said that:

* I was athletic myself (and injured my knees cycling).

* Athletes sometimes are born with physical gifts that could include a better ability to heal.

* Athletes are better conditioned and thus better capable of succeeding in a motion-based program.

All interesting points.

But all irrelevant.

I don’t think it’s what athletes possess physically that matters, but rather their strengths mentally. In fact, that’s why I put quote marks around the word athlete. Because even amateur athletes who have no physical talent at all can be remarkable for their attitude and approach to training.

So here’s what I find impressive about the athlete mindset, and why I think these types are well-suited to beating knee pain the way I did.

* They’re fighters. They’re not quitters. I think they tend to be more optimistic about life in general, or at the least, convinced that their actions affect outcomes in their lives.

* They’re self-motivated and driven. They set a goal and they work toward achieving it, even if that takes many months (which healing bad knees will).

* They’re organized and focused. Ever talked to someone in training for a road race? He (or she) usually is on some kind of schedule: x miles this week, with a couple of longer 10-mile runs say, and an easy run on Monday etc. And meanwhile, during practice runs he's noting splits for each mile and trying to set personal best times. This is someone who will feel comfortable with the knee pain sufferer’s best friend: a good knee pain journal.

* They’re disciplined and willing to make sacrifices. They pass on that extra slice of pie or on “guy’s (or gal’s) night out” because they’re in training, for example. They forgo short-term pleasure to achieve long-term results. They are the kind of people who can lose that 5 or 10 pounds in order to better control their knee pain.

Three Reasons Why “Let Pain Be Your Guide” Can Be Bad Advice

At first I was going to title this “Three Reasons Why ‘Let Pain be Your Guide’ Is Bad Advice.” But, although provocative, that title is rather misleading. You do need to listen to those pain signals coming from your knees and react smartly to them.

So what am I objecting to now? This, in a nutshell: The all-too-hasty examination of a bad knee (or knees) by a medical professional, who concludes with some breezy advice to be careful and “let pain be your guide.”

What’s wrong with that?

* If pain is all you know, it’s probably dead-end advice.

Think about it. Your knees always hurt. You try to minimize the pain (“Let pain be your guide”) by using them less. Before you know it, you’re caught in a death spiral.

The death spiral goes like this: 1. Your knees hurt so you move them less. 2. Because you move them less, over time, they hurt even more.

Now, go back to #1 and repeat the cycle, ad nauseam, until you have a pair of completely wrecked joints.

What can you do if you do hurt all the time? There are ways to move a lot without over-stressing your knees, as I discuss here.

* The advice needs to be more nuanced, to account for the delayed symptom effect.

Knee cartilage has no nerves. When I discovered this, I remember thinking, “Wow. That’s huge.” Indeed, it’s very, very significant for a number of reasons.

One of them: You can overstress and damage knee cartilage and not even know it until sometime later.

Here’s a real-life example (from my own experience): You move a heavy object, such as a pedestal fan, down a couple of flights of stairs. Your knees feel okay at the time. Two days later, you’re out casually strolling and you notice one of your knees is aching.

“Let pain be your guide” suggests that the casual strolling is the activity that should be curtailed (to be fair, you probably do want to take it easy on your walk, even if it didn’t cause the problem). You felt no pain while carrying that fan down the stairs, right?

But when you have bad cartilage, and it’s overstressed, symptoms can take a day or even two to appear.

So, in this example, you run the risk of learning the wrong lesson. Instead of resolving not to carry heavy objects on the stairs until your knees get stronger, you decide your joints can’t handle easy walking.

* The advice needs to be more nuanced, to make more-subtle distinctions.

One thing I learned from battling knee pain: your joints will throw off lots of different sensations. Sure, there’s outright pain, but you need to be able to parse all the sub-pain signals, because some of them indicate that pain, while not present, will be soon if you don’t change what you’re doing.

So, instead of “Let pain be your guide,” I’d suggest “Let sensations from your knees be your guide.” I can imagine someone reading that sentence and rolling his or her eyes. How is that any more helpful?

Well, it isn’t and it is.

Because the next step involves doing some work. You need to figure out what various signals from your particular knees mean. There’s only so much you can learn by studying medical articles about how the knee works and how pain and discomfort arise from damage to cartilage and soft tissue.

Those are general guides. You have a pair of specific knees, with specific problems that will result in an array of weird tinglings and sensations. You need to understand what they all mean. You have to learn the language of “knee,” as it applies to your knees.

If you really do follow “Let pain be your guide,” in a simple way, you’ll probably make the same unfortunate discovery I did. By the time you’re in pain, it’s already too late. You screwed up. You went backward. You need to figure out how to gradually work your way out of pain -- and then, once there, stay there.