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!

Friday, February 18, 2011

Comment Corner: Can Even Badly Damaged Knee Cartilage Heal?

Before the regularly scheduled programming begins: If you've read Saving My Knees and enjoyed it, please drop by the book's Amazon page and post a review. There's no crack team of publicists working the phone for this book -- I'm relying on good old-fashioned word of mouth.

Now here's the second installment of "Comment Corner" (okay, it's a bit hokey as a name), in which I answer a reader comment at some length. Buckle your seat belts; this one is a bit of a long ride!

Last week I was talking about strengthening the knee instead of the surrounding muscles, and exactly what that means. That prompted this comment:
I'm curious about the repair capability of severely damaged cartilage. I had a microfracture procedure in my left knee. My symptoms were primarily mechanical -- my kneecap would catch painfully every time I moved it through a certain angle.

When I got the pictures from the arthroscopy, I noticed that the damaged cartilage almost looked like hair. It looked "fuzzy", with hundreds of tiny strands that had clearly been torn apart. It's hard to describe unless you've seen pictures of it. Mine was worn down to the bone in places.

Do you think cartilage damage of this type can heal naturally through gentle movement? I'm having trouble imagining the mechanism that could promote healing in this case. The chondrocytes are captured in their lacunae, presumably within the loose strands of visibly damaged cartilage. How can they possibly "capture" the free-floating ends of the torn fibers in order to reattach them? I guess I'm having trouble understanding the mechanism that would allow badly damaged or torn cartilage, as is seen in Outerbridge grade 3/4 lesions, to heal. It's easier to understand how it might work in earlier-stage chondromalacia where the cartilage is still contiguous but is soft and has stopped providing adequate shock absorption.
Good questions. I recognize a kindred soul, trying like crazy to figure things out, as I once was.

First, normal cartilage looks like this (images borrowed from Nice and smooth, like a baby's bum:

Then you have "horror show" cartilage. Degenerated, fibrillated, like a fright wig:

Yow! No wonder knee pain patients staring at photos of their scoped joints feel a sickening little roll of the stomach. How the hell does image #2 ever improve and turn back into #1? That would seem about as unlikely as your broken vase, lying on the floor, jumping up and spontaneously reassembling itself.

Okay, let's look at the prospects for healing bad cartilage -- really bad cartilage that looks like a hairy crab. We'll do this in two parts, because there's Stuff I Know and then Stuff I Think Might Be Right.

Stuff I Think Might Be Right

So how does this "cartilage hair" reattach itself, as Anonymous wonders, to make your cartilage whole again?

Thought experiment: Imagine taking a cheese grater (don't really do this!) and barking it a few times, quite roughly, against the skin on your forearm. What's your arm going to look like after you finish? Probably you'll have a lot of little pieces of skin hanging off.

How does this skin then reattach itself to make your skin whole?

Answer: It doesn't, of course. The irregular bits eventually fall off. Over time the surface of your skin heals.

My guess is that something similar probably happens with raggedy cartilage that succeeds in healing. In fact, my best theory of what was going on with my joints -- I had a lot of problems though an MRI detected only "mild" chondromalacia -- is that I had some of this "cartilage hair," at least in certain places.

Now if I'm correct, the "cartilage hair" is just going to flake off. You have to accept that. Further, as it does, little bits of cartilage detritus will migrate to your synovium and make your knee sore. That, too, you have to accept.

What you have to focus on is the underlying cartilage that's intact: That stuff is too soft. It is in prime "hair-making" mode. It will eventually fissure too, turn into synovial seaweed, and go the way of its surface brethren if you do nothing. Which is what a lot of people do: nothing.

The intervention I believed was necessary: strengthening and stiffening the existing cartilage, very slowly. While this process occurs, there will be some pain associated as the bad stuff flakes off and migrates away through the joint. But you need more resilient tissue and the only way to get it is through motion coupled with appropriate load (a big hat tip to Doug Kelsey!).

You may be wondering: what about the chondrocytes (cellular cartilage-making factories) that are trapped in the "cartilage hairs." My guess is they go bye-bye. But if that unduly stresses you (I can tell Anonymous is doing the "extra-curricular reading" and is aware that chondrocytes are not that plentiful to start out with, scattered throughout the tissue), these cells have apparently shown an ability to regenerate.

This is from a prolotherapy Web site -- I'm not saying I'm a fan of prolo, or that I agree with everything on this page (though much of it makes sense), but the cited study is paywalled so I can provide only the prolo summation:
... data suggest that under circumstances of chronic injury, such as is seen in osteoarthritis or trauma, chondrocytes are capable of mounting a significant reparative response and can replicate their DNA to form new cells.
Okay, the above is Stuff I Think Might Be Right. Anyone with more knowledge/insights, please weigh in. Now for:

Stuff I Know

I know that cartilage doesn't have to heal completely, to pristine condition, in order for knee pain sufferers to escape their torments. Most of the population over 30 has some damaged cartilage in their knees. So first thing: the bar you have to jump over is lower than you may think. You don't need normal cartilage again, just cartilage that functions well and doesn't hurt.

I also know that very damaged cartilage has been shown to heal over time. I think the scale being used in studies I've read has been on ICRS grading, not Outerbridge, but if you look at these photos here, the two are similar (e.g., an ICRS Grade 3 is basically an Outerbridge III).

Here are some interesting numbers from a report published in Rheumatology magazine in 2006 entitled "Factors Affecting Progression of Knee Cartilage Defects in Normal Subjects Over Two Years."

Initially, there were 14 locations at Grade 3 (less than 50 percent thickness) in the subjects' knees. Three remained the same and five went to bare bone -- that's the bad news. However the good news is that almost half of them improved: four became Grade 2 and two Grade 1, which is nearly normal!

There were five sites at Grade 4, or bare bone. Now you'd expect at the end of two years, those five sites would still be at Grade 4, absent surgical intervention (such as a microfracture). But one ended up Grade 3, two were Grade 2, and one even healed all the way to Grade 1!

I'm willing to bet that, if these knees with Grade 3 and Grade 4 lesions had been scoped, you'd see plenty of that "cartilage hair."

So far I'm telling a wonderful story, but caveats are in order.

As careful readers no doubt noticed, these were normal subjects. Also it's not clear how big their lesions were. Still, I think the big takeaway is that cartilage can heal, even when you've got no more than exposed bone to work with. That's a really great, inspiring message.

If you're Anonymous, though, what you face is fairly challenging. You've got to give your knees enough motion, and the proper amount of load, without blowing them out, so to speak. This will not be easy. This will take a lot of time, I bet (maybe four or five years).

But, if you can see yourself gradually getting better over that long stretch, it's certainly better than the alternative: resigning yourself to a life of constant pain. Remember, there's always hope.

Friday, February 11, 2011

What Does "Knee Strengthening" Mean Exactly?

My belief is that, to heal bad knees, you need to focus on strengthening the joint -- that's what's causing you trouble after all -- and forget about obsessing over your leg muscles. (You can build up your quads all you want, until they're as thick as tree trunks, after you fix your knees!)

That's how I succeeded in my recovery, which I describe in my just released book, Saving My Knees.

But what does it mean to "strengthen" a joint? In my case, I had to contend with bad cartilage. An MRI revealed I had "mild" chondromalacia (though I had not-so-mild pain symptoms, so I suspect that the problems lay deeper than the MRI could see). So my mission became to restore that cartilage to better health, to make it stronger. But how?

I began digging around in the world of articular knee cartilage. What constitutes weak or poorly functioning cartilage anyway? Obviously, if it's worn down or damaged structurally, the tissue won't work as well. But then I learned something curious: bad cartilage is generally too soft.

Now here's where things can get confusing. If you cruise the Net long enough, you'll find at least one instance of a doctor pooh-poohing the diagnosis of "chondromalacia," saying that the term makes no sense because it means "soft cartilage," and cartilage is supposed to be soft. That's a rather disingenuous thing to say though.

Because chondromalacia means an "abnormal softening of cartilage." Cartilage is somewhat soft because it must act as a rubbery shock absorber, compressing and then bouncing back to its original shape. Cartilage-as-a-brick wouldn't function too well; a brick has no ability to deform to absorb shock, then recover to its original state.

The issue arises with a kind of excessive and unhealthy softness that (at its extreme) is captured in this delightful bit of imagery from the book Heal Your Knees: "If a man in his eighties tears a meniscus, it wouldn't make sense to try to repair it, because that would be like trying to put stitches in a Boston cream pie."

You don't want Boston-cream-pie cartilage, certainly, that can't hold a stitch -- or bear the burden of a walk up a hill. To better understand why, consider this excerpt from Disorders of the Patellofemoral Joint, by John Pryor Fulkerson (my bold):
Closed chondromalacia is common and may or may not be symptomatic ... it consists of simple softening of articular cartilage, which begins in a very localized area and then extends progressively in all directions ... softening, which may at times appear fluctuant, may be present in varying degrees of severity, from simple softening to a more advanced form in which a type of "pitting edema" can be observed after digital or blunt instrument pressure. This loss of elasticity, which this softening represents, decreases the function capacity of cartilage and explains the reaction of adjacent subchondral bone to which the compression forces are transferred abnormally.
There we go. That supplies the needed clarity. Soft = loss of elasticity. Loss of elasticity = not very good shock absorber. Since cartilage's key role is to lessen shocks/forces transmitted through the knee joint, too much softness means lots of problems. Plus there's this to consider: soft tissue is more prone to flaking, fraying and tearing. Flaking off bits of cartilage can be a source of pain, as they migrate through the synovial fluid to the nerve-rich synovium. And I hardly need to belabor the point that you really want to avoid tearing your cartilage.

So my calculus was simple: I didn't want to prematurely have Boston cream pie (or anything resembling it) in my joints. That meant I needed to strengthen and stiffen my knee cartilage (here I'm talking about indentation stiffness, and not brittle stiffness), through a long program of high-repetition "exercise" that gradually increased in intensity.

I knew that approach could work, from a Swedish study ("Positive Effects of Moderate Exercise on Glycosaminoglycan Content in Knee Cartilage"). Moderate physical activity boosted the content of glycosaminoglycans (GAGs) in the cartilage of participating subjects. Having more GAGs in your cartilage is great; they contribute to making the tissue healthier and more resilient.

So for anyone trying to understand how I healed, that was one important, basic insight. I knew my cartilage was weak/damaged/soft. And I knew I had to make it stronger.

And I did, and by doing so, strengthened my knees.

Saturday, February 5, 2011

"What Should I Do If I Have 'Weak' Knees?"

As I promised a while back, occasionally I'll lift a "story" from the comment section and turn it into a blog post. Today is the first installment of that occasional series. For the umpteenth time, I'm not a doctor or physical therapist, so I'll just offer "things to think about" and "observations from my own experience beating knee pain and researching knee injuries." Other readers with insights (which may be much better than mine) are welcome to chime in (my comments section is completely open).

I strongly believe in patients becoming smarter about their knees and pain symptoms so that they are equipped to ask good, incisive, challenging questions of the medical professionals that examine them. That's what I'd like to help people with: getting smart enough to ask some good questions.

So without further ado, here is Anonymous complaining of "weak knees":
Have you or anyone had just "weak knees?" For over 7 years, I have had this issue and have seen a variety of doctors, multitude of tests, physical therapy and still...same old..same old thing. I was wearing a rocker type shoe from Kmart for about 6 months and my weakness went away, but...then my feet started to tingle and get sore from them. It became too tried the Sketcher brand and the weakness came back. So now, I am back to a good pair of running shoes with good support wit weak knees. I am considering on seeking out another orthopedic surgeon's thoughts, but...because I am not in pain they feel nothing is wrong. If I wear knee supports the feeling goes away, but in several days, I get tingling in my feet. One doctor thought that since my knees are OK with supports that by realigning and tightening the knee cap, the problem would be solved. I should be happy that I don't have pain...but...a weakness all day can be just as brutal. No medication works on manage through the day. When I relax at home on the couch, the feeling will go away in about an hour and then the problem starts all over again the next day.
I found this case interesting mainly because of the vagueness of the complaint: "weak" knees. Notice as well the comment "because I am not in pain they (doctors) feel nothing is wrong."

First, I'm going to go out on a limb here and say that, even though nothing is currently wrong, I bet Weak Knees (Anonymous, this is your moniker for the rest of this post :)) isn't that far away from having problems. The fact that something in your body feels amiss is often a softly blinking red warning light. Before my knee issues flared up, I was having twinges in my right knee while cycling uphill. I would adjust my stroke briefly, easing up, then the sensation would go away. So I continued to ride as hard as before, thinking (wrongly) that the problem would eventually just fix itself.

Second, I'm going to put on my swami hat and surmise a few things about Weak Knees. I could be wrong about all three speculations, but let me list them and explain my thinking:

1. There is a good chance Weak Knees is overweight.
2. There is a good chance Weak Knees leads an inactive lifestyle.
3. The physical therapy that Weak Knees did was directed at muscle-strengthening and not at improving aerobic capacity.

Again, I could be completely wrong about all three points, especially because there is so little information given about what "weak knees" means exactly. Do the knees feel like they are about to give way? Do the knees feel like they offer poor support for ordinary daily activities, such as squatting or kneeling? Do they ache at all? Or after climbing a few flights of stairs, does Weak Knees just not feel that good?

The vagueness of this self-diagnosis intrigues me, however. Much of my life I have enjoyed a sporting lifestyle. That means I have spent a lot of time with people who enjoy a similar lifestyle.

And when they have pain in one of their joints, such as the knee or spine, they describe it in a variety of manners, but "weak" is generally not one of them.

Symptoms of diffuse weakness I associate with people who tend to be overweight and out of shape. Excess weight is probably the worst thing I can think of for someone seeking to recover from knee pain or avoid it in the future. That extra fat means your knees have to work much harder to move your body around. That weight discourages you from moving in general. And, I think on some level, being overweight makes people more susceptible to "general malaise" type of disorders.

The best kind of exercise, I'm convinced at the grand age of 49, is something that gets your heart beating without your body taking a beating. That isn't meant to dismiss the benefits of running. I don't believe the myths that knees just wear out from all the pounding of running and inevitably become arthritic, though that may be true for runners who don't watch their weight or who run carelessly (e.g., who take off four months, then try to resume at the level they were at previously without building up their training). But if you've got knee joint issues, cycling (or swimming, or walking) may be a more suitable activity.

If I were Weak Knees, knowing that my joints were just weak and not hurting, I'd first drop onto my weak knees and praise the Lord I've got some time to sort out any issues before the curtain of pain descends :). Then I would talk to my doctor about what aerobic activity might be good for me that would help strengthen the knee joint and improve my cardiovascular fitness. You'd have to start slow, if you've been inactive, but exercise -- SWEATING exercise -- does a body much, much good. It's like acquiring a protective invisible force field against future knee damage (and I have yet to meet a cyclist who's complained of weak knees). I wouldn't waste a minute looking into this.

One last note: if my analysis above is anywhere close to correct, I would NOT have surgery to try to correct this condition. Surgery is generally best considered a last resort for non-specific knee pain. But again, Anonymous, talk to a qualified doctor about this.