Physically Active Children May Have Stronger Knees as Adults

Do you have children?

I have one, age three and a half. The way she uses (and abuses) her little body never ceases to amaze me. I sit and watch, without comment, as she takes part in marathon sessions of charging at the couch and slamming into the cushions.

One time she advanced across the rug, whipping her head violently back and forth, trying to induce dizziness. I recall thinking, “My God, my God -- your neck!”

Is she active? Do bears you-know-what in the woods?

If you have a similarly high-energy toddler, or older child, there’s good news. All that running and jumping about may be laying the foundation for stronger knees later in life.

That, anyway, is what a study of 298 Australians found. Subjects had their strength and fitness tested as children, then researchers did MRIs of their knees 25 years later. The findings, according to this summary article:

Childhood physical activity, including physical work capacity, leg and hand muscle strength, sit-ups, and long and short runs had a significant, consistent association with greater tibial bone area. In addition, higher childhood physical work capacity measures were associated with greater tibial cartilage area.

(The tibia, by the way, is the bone in your lower leg that meets the larger femur in the knee joint.)

Why this beneficial effect? One investigator in the study, Graeme Jones, speculates that it’s as simple as “bone area gets larger to cope with the extra demands put on it by higher levels of physical activity, and then this leads to more cartilage, as cartilage covers the surface of bone.”

Does this mean though that, if you’re an adult who spent his childhood watching cartoons instead of playing kickball, you’re out of luck now?

That seems highly unlikely to me. One thing that impressed me, after doing a lot of reading about knee cartilage while working toward my own recovery, was how dynamic the tissue is. It’s constantly changing -- sometimes for the worse, true, but often for the better too.

It has been shown that the knee cartilage of triathletes is thicker than normal. Is that because they were active as children? I very much doubt that. More probably, it’s because their present-day physical activity is busily modifying their cartilage in a lot of good ways.

Why Is My Story Relevant If Your Knee Pain Differs From Mine?

Sometimes I get a reaction like this to my book:

Interesting story, but it doesn’t really apply to me. The author hurt his knees cycling, while my knee pain is due to nothing related to sports/no identifiable cause/insert something else here. Also, the author struggled with knee pain for about a year, while I’ve had problems for 2 years/5 years/insert some other length of time here. And the author’s symptoms were burning sensations around the kneecaps and difficulty sitting while mine are problems walking/swelling/insert some other symptoms here.

First, don’t misconstrue what I’m about to say as a marketing pitch (Step right up and buy this book! A panacea for all your knee woes, of any kind, of any severity!) Clearly my story isn’t relevant for certain types of knee problems (e.g., a torn ligament). It’s also not useful for a certain kind of person who mainly wants details on specific exercises to do or who seeks an “other” directed solution to his problems.

But for those suffering from that mysterious condition called patellofemoral pain syndrome, or who have been told they have chondromalacia, or who have chronic knee achiness, diffuse burning, pain of unclear origin -- and for those who believe they themselves must be very involved in fixing their problems -- I think it can be of great benefit. Here’s why:

(1) “All happy knees are alike; all unhappy knees are unhappy in their own way” isn’t quite true. (Apologies to Tolstoy.) Which is to say, I think there are a lot of similarities among knees afflicted with patellofemoral pain syndrome, chondromalacia or osteoarthritis.

For example, many problems will relate to damaged cartilage, and they’ll be frustrating to deal with, because cartilage has no nerve endings. This was a major frustration that I faced certainly.

The upshot: What unites us may be more significant than what separates us.

(2) Some good practices are just universal, regardless of your particular symptom set -- for example, the importance of movement or weight loss (or weight control at least, if you’re thin already).

It’s hard for me to imagine a chronic knee pain patient for whom these good practices aren’t relevant. In the book (and on this blog), I’ve supplied more context -- from medical studies, from my own experience, from examples drawing on common sense -- for why they matter so much.

(3) You need the right kind of optimism to succeed, if you’re going to triumph over knee pain.

More specifically, you need optimism grounded in reality. It’s not the optimism of the terminal cancer patient who, with a 1 in a million chance of a cure, stubbornly vows, “I’m going to get better.” It’s the optimism of a reasonable, intelligent person who thinks he or she can get better because there’s plenty of evidence supporting that belief.

The book is largely about providing the proper context for such optimism. You can get better because I did is part of the message. But you can get better because defects in bad knees can heal -- that’s a bigger, universal message worth shouting from the rooftops. And scientific evidence for that assertion is in the the book (and on this blog).

I believe my story does have a wider relevance than here’s-one-thing-that-worked-for-one-guy. My hope is that others will have their own success stories, following similar principles, and together we can force doctors and physical therapists to rethink how they treat chronic knee pain.

Does Vitamin “D” Stand for “Dud” When It Comes to Knee Pain?

In case you haven’t noticed, vitamin D has become the “in” vitamin over the last four or five years. I’m not sure I'd be surprised if a study claimed that takers of a vitamin D supplement sprouted wings and learned to fly. It seems that good. (Full disclosure: I take a vitamin D pill daily.)

But for knee pain, don’t get your hopes up.

This recent study showed that taking vitamin D supplements did not (1) slow the progression of knee osteoarthritis or (2) reduce the associated discomfort. And, for knee pain, those are really the only two things that matter.

146 patients, who were 45 or older and who had symptomatic knee osteoarthritis, participated in the trial. Half received a strong dose of vitamin D (2,000 IU each day); the others got a placebo.

At the end of the two-year study, 61.3 percent of the supplement takers had the desirable level of vitamin D in their blood of 36 ng/ml or higher. That compared with 8.3 percent of those who took the placebo. Yet there was no significant difference between the two groups in terms of pain or cartilage loss.

Earlier studies had suggested that higher levels of vitamin D in your blood might somehow play a part in slowing the progression of arthritis. But alas, it appears not to be so.

Now for my take: Pills are easy. Surgery is relatively easy too (you put your faith in someone else to make you whole again). It doesn’t surprise me that the “easy” stuff to fix chronic knee pain usually doesn’t work. That feels right to me, like cosmic karma.

What’s hard is slowly and diligently and patiently rehabbing your knees. It’s not hard like pushing a boulder up a mountain is hard. It’s hard because it requires you to be completely engaged in the process of healing, every day.

Someday, maybe someone will find a magic pill that will allow you to effortlessly banish knee pain. But I wouldn’t count on it.

A Deeper Look at Hip Strength and Knee Pain (Part II)

Last week, in Part I, we looked at shortcomings in the structuralist explanation of how hip weakness causes knee pain.

This week, we get down to brass tacks.

If studies have shown hip strengthening reduces knee pain (and let’s assume for now that many studies have shown this, though I don’t know if that’s necessarily true), one attitude might be:

Who cares why it works? I’ve got bad knee pain. I’ll try anything that works, especially if it’s gone through the crucible of rigorous scientific testing.

So this week we’ll look at that argument, but in an unusual way. The first half of the post will be simple and visual (Cool! Pictures!).

Hey, why not have a little fun? :)

So, in other words, we’re going to start with a:

Now then, if you’re a carpenter, you’re familiar with the image below. Even if you’re not a carpenter, I bet you know what it is:

That’s right. A nut and bolt. There are many, many things in this world joined by nuts and bolts. But what if, at some point, you need to remove that nut? Hmm. How are you going to do that.

Now I know everyone knows what this is:

Praise be to opposable thumbs! Using your fingers, if the nut isn’t screwed on too tightly, you can remove it.

Let’s be charitable and say FINGERS are OKAY for removing nuts from bolts. (Actually, if we’re honest, we’d rank them as short of OKAY. But at least they’re better than nothing.)

“OKAY” isn’t very good though.

What about this instead:

A pair of pliers! That will certainly work fine -- for most nuts tightened to bolts. So let’s say PLIERS are BETTER at removing the nuts. We’re making progress!

But, alas, you’re going to run into that really-tightly-screwed-on nut or that rusting nut or that difficult-to-remove-for-whatever-reason nut. Sweat will break out on your forehead as your trusty pliers succeed only in stripping metal off the fastener’s edges.

Hmm. What works better than pliers?

How about these:

Yup. Socket wrenches. The mouth of the wrench fits snugly over the six-sided nut. It’s the perfect tool for the job. This is what the socket wrench was designed to do, tighten and remove metal hexagonal-sided nuts.

That doesn’t mean it will always work. There are times it will fail. Still, it does the best job.

So let’s say SOCKET WRENCHES are BEST at removing nuts from bolts.

Okay, we’ve reached the end of the picture book session. :)

What does all this have to do with rehabilitating bad knees by strengthening your hips? Well, actually it has more to do with the Big Picture: finding the best way to rehab your knees.

Imagine a one-year study broken into the following groups of chronic knee pain sufferers:
(1) 100 people who do nothing but live their ordinary, rather sedentary lives (our control group).
(2) 100 people who go through a program of hip strengthening.
(3) 100 people who go through a program of quad strengthening.
(4) 100 people who go through a program of high-repetition, low-load activity that only gradually increases in intensity (basically, the kind of program that saved my knees).

Say that in the original 100 people, the knees of 5 spontaneously get better after one year. Not many, but a few. So that’s our benchmark.

Now the 100 people who go through hip strengthening will potentially get several benefits. They should gain from getting in at least some activity (by doing exercises related to hip strengthening, which is certainly better than sitting around on the couch). They may benefit too from the placebo effect -- the mere fact that a physical therapist is working with them will encourage some to think they’re getting better. (Note: One problem with such an experiment is that it can never be truly blind for participating subjects; it’s impossible to disguise who’s getting the physical therapy attention and who’s not).

Still, I would guess that many will not get better.

Say in the hip strengthening group, the knees of 20 subjects appear to improve. If you just compare hip strengthening with doing nothing, then you have to conclude: strengthening the hips is a winner!

But what if we look at the quad-strengthening group -- there have been studies showing that quad strengthening helps bad knees. Strong quads arguably have a more direct effect on the joints and can help cushion them from harmful impacts. While the quad exercises will probably be too strenuous for some knees, others will tolerate them fine.

Say in this quad strengthening group, the knees of 35 subjects improve. Once again, if you just compare strengthening the quads to doing nothing, bulking up the quads wins the day!

But what if, in the last 100 people, who are trying to heal the joint itself, there is even more success? Say in this group, the knees of 80 subjects improve. Now where are you?

Well, the analysis would be something like this:

HIP STRENGTHENING is OKAY for beating knee pain.
QUAD STRENGTHENING is BETTER for beating knee pain.
JOINT STRENGTHENING is BEST for beating knee pain.

Naturally, this is what I expect such a study would show. It’s a shame no one has done one, so we don’t know.

If this is the case, the fact that quad strengthening shows some success, as does hip strengthening, tends to muddy the waters. They work okay for treating patellofemoral pain syndrome, but not great. In fact, where we’re at today in terms of standard treatments for managing PFPS can be summed up like this: Nothing works very well, but a number of things work better than nothing. (If you doubt this point, just review the literature about this condition -- I have -- and see how often medical professionals complain that PFPS is a mysterious problem that’s hard to solve. That's the best indictment I know of the standard treatments.)

But the fact they sometimes work means people keep using and trying to modify them. Unfortunately, no one seems prepared to make the radical (yet simple) leap: Why not just try joint strengthening? It’s an injured knee. Maybe it just needs to be healed, just as other injured structures do?

Closing note: I can imagine a structuralist type fuming about the statements “hip strengthening is okay” and “quad strengthening is better” with the remark, “Well, it depends on what’s causing the knee pain in the first place! Maybe hip strengthening is great for weak hips and quad strengthening the best approach for problems related to weak quads!”

But let’s get real for a moment. The fact is, right now, the mass of patellofemoral pain syndrome sufferers are basically like those in the hip strength study I began this series by looking at: They suffer “diffuse peripatellar and retropatellar pain of an insidious onset” and there’s no clear sense of what’s going on. Six different medical specialists may say six different things. A LOT of confusion surrounds PFPS. So in my hypothetical study above, I’m just assuming we round up a lot of PFPS patients with diffuse knee pain that appears to have an unclear origin -- because that’s what the real world looks like.

Maybe someday, in another 10 or 20 years, we’ll be at the point where we can focus on comparing hip strengthening to knee joint strengthening for specific subsets of patients, who fit certain criteria that leads some to believe their hip weakness is the essential contributor to their knee pain. But even so, I’m betting that, if put side by side, joint strengthening would prove superior as a treatment. Hopefully, someday we’ll see.

Taking a Deeper Look at Hip Strength and Knee Pain (Part I)

Today I’m revisiting the relationship between knee pain and hip strength. That’s because after this post, in which I mentioned a study that showed that strengthening muscles in the hip didn’t improve the biomechanics of runners, I got this comment from “Knee Pain”:

You've cited studies saying that these types of structuralist exercises don't help knees. I'm wondering if there are some other studies that show that these exercises to help knees? Otherwise, gosh, where are our physical therapists getting the guidance to tell us all to do all these hip/glut exercises? (I've been given that advice by three professionals helping me with my knee problem.)

This is a very good point.

It’s not as if a couple of physical therapists were lying in a meadow, gazing at cloud formations on a lazy summer day, and one said to the other, “What about the hips? Try strengthening the hips?” And the other replied, “Sure. Why not?” So they began treating chronic knee pain by focusing on stronger hips, other physical therapists blindly followed their lead, and this treatment gradually became accepted protocol.

On the contrary: Therapists giving you such advice might cite various studies of their own if pressed for evidence. For example, here’s a recent one that looked at 28 female subjects with patellofemoral pain (14 underwent hip strengthening, 14 constituted the control group).

It reaches what looks like a slam-dunk conclusion:

A program of isolated hip abductor and external rotator strengthening was effective in improving pain and health status in females with [patellofemoral pain] compared to a no-exercise control group. The incorporation of hip-strengthening exercises should be considered when designing a rehabilitation program for females with PFP.

Here’s another one -- actually it’s a couple of case studies, so only two subjects were involved. For both individuals, treatment “occurred over a 14-week period and focused on recruitment and endurance training of the hip, pelvis, and trunk musculature.” The result, in part:

Both patients experienced a significant reduction in patellofemoral pain.

Well, that does seem convincing! But let’s take a step back and ask, more deeply: What do such studies really show?

MINDING THOSE P’S and Q’S

First, let’s look at a slightly different kind of study, though it’s very much related. The researchers wrote up its results in the January 2008 edition of the Journal of Orthopaedic & Sports Journal Therapy. It goes by this rather dull name:

Hip Strength and Hip and Knee Kinematics During Stair Descent in Females With and Without Patellefemoral Pain Syndrome.

A prominent star on the online copy of the report signifies that it won an “excellence in research” award by a sports physical therapy group.

The researchers begin the journal article with a sort of embarrassing sidenote, if you’re a believer in the pre-eminent role of structure in causing injuries. For a while, there was a fascination with the relationship between the “Q angle” (the quadriceps angle, which shows the propensity for the patella to track improperly) and patellofemoral pain syndrome. The hypothesis: The size of the Q angle correlates with the incidence of knee pain (the larger the angle, the more problems). Women in particular, with their wider hips, are likely to have a larger Q angle.

However, “many studies have not supported the relationship between an increased Q angle and PFPS [patellofemoral pain syndrome],” we are told.

Oh well.

Moving along.

REACHING FOR A HOLISTIC THEORY 

The “Kinematics During Stair Descent” study delves into why hip strengthening makes sense as a treatment. Now this is actually a very important thing if you want a solid, holistic theory of the relationship between weak hips and bad knees. It’s one thing to show that strengthening the hips helps reduce pain (which we’ll return to later), but why?

Okay, remember the simple “x leads to y” explanation in my earlier post. I’m going to use that, except with some big words thrown in:

Hip abductor and hip rotator weakness --> too much hip adduction and internal rotation --> stress on the patellofemoral joint causing pain.

Again, the short form:

Muscle weakness in hip --> bad form --> knee injury

So, based on this analysis, what would you expect to find in people with PFPS? A couple of things: (1) weak hip muscles (2) bad form.

HOW THE STUDY WAS SET UP 

The study’s methodology appears pretty solid (to my relatively untrained eye).

The experimental group consisted of 18 females with PFPS who reported to the University of Kentucky Biodynamics Laboratory for testing. Each was matched with a healthy female (the control group), in terms of age, weight and height.

Subjects with PFPS were asked to rate their pain. Also, all participants had their leg strength tested, by a handheld dynamometer that was 99 percent accurate. For the researchers to be able to make careful observations about form, everyone in the study was videotaped with a seven-camera system as they descended a short set of stairs while wearing reflective markers at key locations on their bodies.

The results: Weakness in hip muscles was indeed found. The subjects with knee pain “generated 24 percent less hip external rotator torque and 26 percent less hip abductor torque compared to controls.”

So far, so good for the structuralist model. Then the problems start.

FIXING A PROBLEM THAT DOESN’T EXIST

The study’s other major finding, beyond that of weak muscles, undoubtedly made its researchers more than a tad uncomfortable:

Subjects with hip weakness did not demonstrate excessive hip internal rotation, hip adduction and knee valgus compared to controls.

Oops.

Remember our causal chain again:

Muscle weakness in hip --> bad form --> knee injury

In the structural analysis, strengthening the hips should work because it corrects the bad form that caused the injury.

But if there isn’t any evidence of “bad form,” what does that mean? Why are you trying to fix “bad form” if there’s no “bad form” to fix?

That’s a head scratcher, but there’s an even bigger revelation -- a real bomb -- that the authors of the report drop at the end.

THE STUDY’S BOMBSHELL

Before we get to that, imagine that I tell you that 90 percent of everyone with patellofemoral pain syndrome in a study is found to also have something I refer to as “x”. You might think, “Well, let’s find a way to get rid of ‘x’! That should correct their PFPS!”

Then if I told you “x” was “depression,” you might retort, “Of course they’re depressed! They have knee pain. Take care of the PFPS, and you’ll get rid of the depression!”

Cause and effect. It’s absolutely critical to get those in the right order.

Now, for the University of Kentucky study, check out this admission about the weaker hip muscles (my bold):

It remains elusive if such weakness was the cause or the result of PFPS.

CAUSE AND EFFECT: WHAT MAKES THE MOST SENSE?

That’s a hole big enough to drive two trucks through. Think about it. The patellofemoral pain syndrome subjects had weaker hip muscles. But what are the chances they had weaker quad muscles too -- and weaker other leg muscles as well? After all, we’re told that the average duration of their problems was 14.4 months, “indicating a chronic condition.”

What happens when you have a chronic condition that discourages you from using your legs and knees normally, so you use them less? The associated muscles weaken. That’s a powerful argument for PFPS helping to create weak hips, not the other way around.

And, if the structuralist model was correct, you’d at least expect to find evidence of bad form during the stair-descending exercise -- which wasn’t the case.

So the structuralist explanation for weak hips causing knee pain appears to be a long way from proven.

But let’s return to the original studies. They show that strengthening hips did reduce knee pain. So maybe your attitude is this:

Who cares why it works? Maybe it works for a different structuralist reason. Maybe it works for a non-structuralist reason. All that matters to me is it works! Why don’t I do it for that reason?

Next week: Why not, indeed? A look at the Big Picture when it comes to treatments for patellofemoral pain syndrome.

Update: Since writing this, I've found this good essay by Paul Ingraham, "Does Hip Strengthening Work for IT Band Syndrome?", in which he asserts "'weak hips' is a weak theory." Have a look!

More Evidence on the Limits of Surgery

What would you do, if you were a surgeon, and a knee you happened to be operating on for an ACL tear was found to have deep cartilage lesions?

This seems like a no brainer, right? You’re already inside the joint. You see damaged cartilage. Why not fix it, to the best of your ability?

Well, what if your intervention makes absolutely no difference.

Check out the findings of this study.

Between 1991 and 1995, 43 patients were treated during surgery for tears of the anterior cruciate ligament but not for associated cartilage lesions. The defects were significant too: Outerbridge grades 3 and 4, signifying that at least half the cartilage, and sometimes all of it, had worn away at a given location.

The study’s researchers followed up with the subjects 10 and 15 years after the surgery. Outcomes were compared with those of a matched group who had the same operation performed, and who went through the same rehab program, but who didn’t have any cartilage lesions.

The difference?

None.

There was absolutely no disadvantage to leaving those severe lesions untreated.

In fact, there may have been an advantage. Because consider this: The best possible outcome should be that of the group with ACL tears but no lesions. But the group with ACL tears and lesions that were left untreated fared as well as this “gold standard” group.

That leaves one group that wasn’t included in the study: patients with ACL tears and treated lesions.

How would such subjects have done? It’s impossible to know, but they couldn’t have done any better than the other two groups, be definition. There’s no way that a surgeon can “fix” cartilage defects in a way that makes them better than what they were before the tissue was damaged. But it’s possible that these people might have done worse. Yikes!

One of the authors of the study, Wojciech Widuchowski, said in a presentation (my bold):

Our conclusions are these cartilage lesions found during ACL reconstruction left with no treatment do not appear to affect the clinical outcome at 10 and 15 year follow-up. Our study seems to reinforce the question whether treatment of a symptomatic lesion provides improvement over that of the natural history.

So the study has good and bad news:

(1) It’s pessimistic about the ability to improve areas of bad cartilage in the knee joint by using surgery to “clean up” or otherwise fix them.

(2) It’s optimistic about the ability of knees with damaged tissue to do acceptably well on their own (Note: that’s what the results seem to suggest anyway).

Strengthening Your Quads: Another Reason It’s a Failed Approach

A number of times, I’ve expressed my frustration with physical therapy’s obsession with quad strengthening to treat weak, painful knees.

On this blog, I once compared strengthening your quads before strengthening your joints as being similar to putting your shoes on before your socks.

And in Saving My Knees, I related how following this advice almost ruined my knees.

To me, this approach just doesn’t make much sense.

Now here’s some clinical evidence:

In September 2010, the Journal of Pain reported the results of an interesting study. The question that researchers set out to investigate: Does knee pain reduce muscle strength?

A test was performed on 18 healthy subjects. To create knee pain, “hypertonic saline” was injected into the fat pad near their patellas. After that, subjects had their maximum muscle strength measured while flexing and extending their legs. On a separate day, a placebo that caused no pain was injected into the fat pad, then the strength measurements were made again.

The findings: muscle strength was 5 to 15 percent lower under conditions of induced knee pain. The amount of reduction was proportionate to the severity of the pain. The conclusion (my bold):

This study showed that knee joint pain has a significant impact on muscle function. The findings provide evidence of a direct inhibition of muscle function by joint pain, implying that rehabilitative strengthening exercises may be antagonized by joint pain.

In other words, your joint pain is working at cross purposes with your attempts to strengthen muscles in your leg. You’re trying to make muscle fibers stronger when they’re able to effectively function at only 85 to 95 percent (or maybe even less, if your knee pain is quite severe) of capacity.

Now be careful to grasp the full import here -- the 85 to 95 percent doesn't refer to the percentage of your maximum strength if you were fit and toned. It’s 85 to 95 percent of your existing strength.

You may be thinking: Well, 85 to 95 percent doesn’t sound too bad. But remember the optimal way to strengthen muscles. You push them to their limit, then they respond by going through a repair/rebuild cycle.

But if you can recruit only 85 percent of their strength, how can you push them hard enough? (Note that I’m not even addressing the elephant in the room -- should you try to push this hard anyway and risk further damage to your joints?)

By the way, an interesting corollary to these findings should be that the worse your knee pain is, the less successful the strengthening approach should be. And, at least based on anecdotes I’ve heard, that sounds just about right.