What Implications Does “Envelope of Function” Have for Designing a Plan to Beat Knee Pain?

Last week I described Scott F. Dye’s common-sensical idea of the “envelope of function.” He believes that patellofemoral pain patients should try to “maximize the range of painless loading for a given symptomatic joint (envelope of function) as safely and predictably as possible.” Such an idea is consistent with my own belief in slowly strengthening a damaged joint.

This week, I want to consider implications of the “envelope of function” perspective. In other words, how does it translate into practice?

At the end of this post, I’ll tell you what Dye himself recommends for treating achy knees.

Before that, I want to share my own observations about what “envelope of function” implies.

But even before that, it’s worth taking a few moments to examine which popular theories Dye rejects as insufficient to explain knee pain. Doing so helps explain what compelled him to develop his analytical framework in the first place.

Dye, a long-practicing orthopedic surgeon, surveys current approaches to handling patellofemoral pain with more than a touch of dismay. What he sees are theories that often lead to “corrective” surgery that is worse than ineffective; it actually harms the patient.

For one, some in his field are obsessed with cartilage to the point that they try to fix damaged tissue through chondroplasties and microfractures. (Note: here my thinking somewhat diverges from his, on the role of bad cartilage in contributing to knee pain, but that’s a long digression -- in any event, I think he’s right that much surgery is unnecessary).

As Dye observes, the level of pain a patient experiences doesn’t always correlate well with the degree of chondromalacia in the knee. You may have advanced chondromalacia and no symptoms, or articular cartilage that appears normal that’s associated with a very painful joint (all true, but I think the total picture is a bit more complex).

Dye also rejects the “malalignment” school of thinking (what I have often disparaged as “structuralism”), which commonly blames knee pain on an improperly tracking kneecap. He gives several reasons why this analysis doesn’t make sense.

If the presence of observable factors of malalignment is so important ... why does one find patients with bilaterally radiographically determined patellofemoral malalignment [that is, mistracking in both knees as indicated by X-ray], with only unilateral symptoms [that is, symptoms in only one knee]?

Or there’s this to ponder:

Why do more than 90% of patients with anterior knee pain who have a diagnosis of malalignment as the cause have a successful response to conservative therapy, even though there has been no documentation of long-term restoration or correction of the supposed causative underlying indicators of malalignment.

Finally, he points out:

The malalignment theory also does not explain the variability of patellofemoral symptoms in the same patient at different times, including the presence of sharp pain on occasion and then dull aching pain on another.

He does recognize that “some patients have clinically significant malalignment” that responds well to corrective treatments, such as a lateral release. “However,” he goes on to caution, “in my experience, the numbers of these patients are relatively few.”

Finding the blame-the-cartilage and blame-the-malalignment frameworks for understanding and dealing with knee pain wanting, he comes up with “envelope of function.” But what does this perspective imply, in practical terms, if you’re trying to fix a couple of bad knees?

Here are what I consider two interesting implications:

“Envelope of function” is kind of a big tent idea. That is, you can interpret it as being somewhat agnostic about the origin of knee pain. What matters, a believer could argue, is the fact that you have a certain degree of knee pain and, given that, what’s the best way to heal?

For example, I thought my pain stemmed from cartilage problems. Maybe I was right. Maybe I was wrong. Arguably, an “envelope of function” approach works in either case because, primarily, your concern is staying within the range of loading that your joint can tolerate.

Obviously, this concept wouldn’t make sense for a patient who has an important, identifiable contributor to knee pain that must be dealt with before healing can occur -- the equivalent of an iron spike sticking out of the joint that must be removed first. But I don’t think that describes the vast majority of patients who have chronic knee pain.

An “envelope of function” approach suggests it’s absolutely critical to determine that range of optimal loading for your bad knee. The best place to do this, in my opinion: at a doctor’s or physical therapist’s office, using machines/devices that can quantify exactly how much load your knee can safely tolerate.

Yet very few medical professionals attempt to do this. This is one reason I think we’re still in the Dark Ages on treating chronic knee pain. The American military can fire a cruise missile down a chimney 1,000 miles away, but the U.S. medical establishment can’t (or has no desire to, more significantly) measure how much force an individual can safely put on a bad knee joint, over the course of a 24-hour day.

Now, what does Dye himself recommend for patellofemoral pain patients, besides a “scrupulous adherence to load restriction within the patient’s reduced envelope of function”?

An anti-inflammatory program.

He appears to favor icing and medication, and approvingly cites a regimen of icing 15 to 20 minutes, two or three times daily.

Indeed, runaway chronic inflammation -- the undesirable kind -- is a problem among those who have constant knee pain. I’m a little leery of his solution though, as I usually associate icing and medication with people who use both to keep doing unhealthy things (such as running when their knees aren’t strong enough). Also, icing and medication interfere with the signaling you get from your knees that’s often telling you, “Stop doing that!” (sitting, standing, whatever)

Still, anti-inflammatories may be a good idea, if used smartly.

He also supports painless (his emphasis) muscle strengthening, stretching and patellofemoral taping.

My own opinion (as I’ve made clear on this blog): stretching isn’t of much use but if it feels good why not?, muscle strengthening should be put on the back burner completely in favor of “joint strengthening”, and as for taping -- sometimes it can offer relief, so why not try it as an interim measure?

“A period of 6 to 9 months of conservative therapy often is required” to improve an ailing joint, Dye informs us soberly, then warns: “The first pain-free day does not mean that the envelope of function has been fully restored but that healing is occurring.”

Getting to the right healing program isn’t easy, as Dye observes. “It is not unlike trying to find the numbers to a combination lock.” True, so true. However, when you succeed in finding the right sequence that springs that stubborn lock, and get squarely on the long-term path to getting better, it’s really a great feeling.

Why You Need to Know About the “Envelope of Function”

Ah, where to begin?

This will be a two-parter because there’s so much to say.

First, anyone who’s read Saving My Knees knows that I openly acknowledge a huge debt to Doug Kelsey, a very smart physical therapist who heads a clinic in Austin. His writing showed me (1) Bad knees can get better; don’t listen to any doctor who says they can’t (2) The right kind of exercise to rehab a bad knee joint is low load, high repetition.

At some later point, I found Paul Ingraham on the Internet. Ingraham, a former massage therapist in Vancouver, wrote long essays that were sharply reasoned and easy to read, often debunking things that 99 percent of his colleagues believe. He showed me that (1) stretching probably isn’t of much use at all (2) physical therapy’s obsession with “crookedness” has led the profession down a questionable path.

So I had managed to stumble across, quite fortuitously, two therapists whose insights possessed great appeal. All that was missing, really, was a doctor to provide a more formal framework for the right way to understand chronic knee pain.

Enter Scott F. Dye.

I’ve been aware of some of his ideas (such as the “envelope of function” and the importance of tissue homeostasis) for a while, but only recently (because of a reader comment) was prompted to look into them more deeply. And I’m glad I did.

The idea of the “envelope of function” is the cornerstone of his thinking on nagging knee pain. He describes it as “the range of painless loading compatible with tissue homeostasis of a joint without causing structural or physiologic injury.”

In other words, there’s an optimal range of load-bearing activity for your bad knee, within which healing can occur. If you drift outside of this range, or envelope -- either by pushing your knee too hard or not placing any demands on it at all, which leads to its own problems -- you’ll thwart that healing process.

Simple, and spot on, from my own experience.

Dye identifies a problem many of us face after hurting our knees:

The envelope of function, or the safe range of painless loading, frequently diminishes after an episode of injury to the level where many activities of daily living that previously were well tolerated become symptomatic, leading to the prolongation of symptoms.

Huge.

This is exactly the issue for so many people, but they don’t modify their behavior in response. The above quote brings to mind a wince-inducing comment I recall reading once from someone who couldn’t climb stairs without pain. His solution? “I just pop a couple of Advil.”

Umm, right.

And people like that wonder why their knees never heal?

So if you want to fix your bad knees, it’s important to determine your own “envelope of function” and faithfully stay within it, healing slowly and steadily. Of course that does raise a bunch of interesting questions about the therapeutic implications of an “envelope of function” approach to beating knee pain.

Next week I’ll look at some of those.

Another Reason to Think Twice About Surgery

Operations to repair a torn meniscus are fairly common. I once thought this was one of those instances where surgery was appropriate. How else would this rubbery disk in the knee joint, only a small part of which receives a flow of blood, get better?

But maybe I was wrong.

If you’re older, and have a meniscus tear, it appears that you’ll do just as well skipping surgery and focusing on physical therapy instead. That’s according to a Brigham and Women’s Hospital study, the results of which were published a few months ago in the New England Journal of Medicine.

351 patients, aged 45 and older, who had a torn meniscus and arthritis as well were randomly assigned either to surgery or six weeks of physical therapy (those whose treatment consisted of physical therapy were allowed to have surgery if their bad knee didn’t improve; 30 percent opted to do so before the end of the one-year study).

The patients who didn’t have surgery fared as well as those who did. They had a similar level of pain relief and improvement in function. (Note: It’s important to point out that chances are good they had less severe meniscus tears that were more likely to heal without intervention.)

There’s still a role for surgeons, notes Dr. Jeffrey Katz, who led the study and was quoted in this Boston Globe summary of the results.

Immediate surgery may ... be more appropriate for younger folks who get a torn meniscus from an injury rather than from arthritis and aging, according to Katz, since previous research suggests these sudden tears often require surgery to fix and take longer to heal on their own. People in their 20s and 30s also recuperate more quickly from the procedure than those over age 65.

Even so, it’s nice to know that studies are confirming what a lot of us already suspect: that for a lot of knee problems, surgery shouldn’t be considered the first option, but rather the last.

What I Like About ‘Taking Smaller Steps’

Have you ever seen a sand mandala?

They’re beautiful. Tibetan monks painstakingly arrange grains of brightly colored sand in striking patterns to create them. (And then, finally, they are swept away -- so there’s always a larger, humbling message about our impermanence in a permanent universe.)

When you stand before one, the feeling must be one of awe.

Last week I wrote about “Runners Knee Cured,” an interesting and entertaining success story. The punchline was that, after taking pain pills and stretching and icing and getting bad (and conflicting) advice from doctors and trying half a dozen other things, the author fixed the problem himself.

The two-word solution, embarrassing in its simplicity:

Smaller steps (while running).

This week I decided to write about what I like so much about “smaller steps.” The first part of the appeal is really on a figurative level. Saving bad knees, like creating a mandala from nothing more than bowls full of dyed sand, requires enormous patience and great attention to detail. And, like putting together a mandala, it requires “going small.”

Metaphorically, for one, you must take smaller steps.

I found it very comforting when I concluded that fixing my knees would take many months, or even years. Why? Because I could get off the crazy up-and-down merry-go-round of hope and despair, where one week I felt a bit better and thought I was making progress, then the next I felt worse and a lost, hopeless feeling returned.

Adjusting to a long timeframe for healing is what I call “getting on cartilage time.” Getting better will demand extraordinary patience, as you slowly push your knees harder. If you walked two miles a day this month, next month maybe you increase that to three. Or maybe only to two and a half.

So the advice “take smaller steps” has a figurative appeal to me.

But I also rather like it as a literal prescription. Take smaller, easier steps. Reduce the impact on your joints. Nothing wrong with that!

I recall the many months I spent working toward my recovery. I did take smaller, slower steps. I knew I was injured and had to heal, but the process couldn’t be rushed. I knew that I needed to move my joints, but at the same time I tried to reduce the forces being transmitted through them.

You should have seen me walk downhill. It was like there was an egg between the bones in my knee joint that I was in fear of breaking. That’s not because of any sensations of pain; rather I knew that walking downhill posed special risks because it’s easy to let your legs slam forward, step by step, propelled by gravity. I actively resisted that tendency.

And I’m sure I was taking smaller steps while doing so.

So this part of his story really resonated for me. I like the simplicity of the message, and the advice works on multiple levels.

Note: Commenters have noted that the author of "Runners Knee Cured" actually had his knee pain return. If so, I think there's a good message of caution in the coda to his tale: Healing painful knees is very, very slow and be careful of declaring victory prematurely.

A Quick Note About Comment Spam

I've been getting a lot of comment spam lately.

Comment spammers are kind of like parasitical worms. Instead of building a website themselves, they try to leech off someone else's hard work.

Again: I don't mind if you post a comment vehemently disagreeing with me (just try to be civil). I don't mind if you link to something that's relevant to the topic, or talk about something (a product, book, lifestyle change, whatever) that helped you beat knee pain.

What I object to are empty comments that are designed purely for advertising such as:

Really fantastic post. I couldn't agree more. Check out my blog/website at grubforbreakfast.com.

So I encourage everyone never to follow a spammer link. I'm scrubbing them off the blog's comment section as fast as I can. However, I think the only way to kill these pests may be to change how I handle comments. I may try to erect a "low fence" to keep parasites out, but not be too bothersome to the people who actually have bad knees and who have worthwhile things to say.

Update: I have just enabled "word verification" on comments. Shouldn't slow real people down more than a couple of seconds and (hopefully) will drive away the spambots. Let me know how it works!

How One Runner Found Knee Pain Relief

As readers of this blog know, I like to share success stories.

A rather interesting, somewhat humorous one came to my attention not long ago. In the comments section of a recent post, Ron Wiltse provided a link to “Runner’s Knee Cured.” The author recounts in an entertaining, visual fashion everything that failed to fix his runner’s knee -- before he finally found a two-word solution to his troubles.

What are those two words? To heighten suspense, the solution isn’t immediately revealed. First comes a staggering list of everything that didn’t work.

If you’ve battled chronic knee pain, this will be a depressingly familiar list. It includes stretching (which led to more intense pain), shoes to correct over-pronation (more pain), physical therapy that emphasized leg strengthening and stretching (yet more pain), ice bags (resulting in cold knees presumably with underlying pain).

The failures also included ibuprofen, custom-made orthotics and a $4,000 treadmill with “SOFT” suspension. And he had a close call with “lateral release” surgery (the operation was to correct a supposed “Q angle” problem that led to a mistracking kneecap -- or two bogus issues -- but he got impatient in the surgeon’s waiting room and left. Smart move, as I think the number of unhappy lateral release patients is fairly high).

Okay, no more suspense. So what worked?

Spoiler alert: If you haven’t read “Runner’s Knee Cured” and wish to, please do so now, because I’m about to reveal the happy conclusion.

This is what cured his years-long ordeal with knee pain:

Taking smaller steps while running.

This, he claims, is why it worked:

He stopped landing heels first when he ran.

So what do I think about (a) his analysis of the problem and (b) his solution?

One I rather like, the other not so much.

This week I’ll tell you what I don’t like so much, and why. Basically, it’s the implication that runners who heel strike are guilty of bad form while forefoot striking is the proper technique.

Let me preface the following with an admission: I haven’t looked much into this matter of “How is the foot supposed to land during the act of running?” But I did come across a thoughtful 2008 essay on the topic on The Science of Sport website (I like the skeptical, fact-based way that authors Ross Tucker and Jonathan Dugas think), as well as a nice summary piece by Gretchen Reynolds on a New York Times blog just a few months ago (“Is There One Right Way to Run?”). The following is mainly based on those sources.

Now, if you believe that landing forefoot first is the “correct” way to run, you probably believe one or more of the following:

Most good runners run this way.

Running this way makes you faster.

Running this way best approximates how our barefoot ancestors ran (in other words, all this “heel striking” can be blamed on the modern fat-cushioned running shoe).

Running this way reduces injuries.

But all these claims appear dubious.

Most good runners run this way.

Most elite runners are actually heel strikers. A study of Japanese runners in a half-marathon showed 74 percent were heel strikers (only 1 percent were forefoot strikers, and the rest landed on their midfoot). A study of more than 2,000 runners at a Milwaukee marathon found 94 percent struck the ground heel first.

Running this way makes you faster.

Remember our old friend “cause and effect”? Well, it may not be that running on the balls of your feet makes you faster, but rather that when you run faster, you naturally run on the balls of your feet! (Try it -- IF you don’t have knee pain! Run slowly, then pick up speed to a sprint, and notice how the landing position of your feet changes.)

Running this way best approximates how our barefoot ancestors ran.

You may believe this in part because of a Harvard study (published in 2010) of lifelong barefoot runners from Kenya. Almost all turned out to be forefoot strikers. But then a newer study came along of a different barefoot Kenyan tribe, the Daasanach. And most of them were heel strikers, with hardly any forefoot strikers.

(Curious note: why were members of the tribe that Harvard researchers studied mainly forefoot strikers? Well, during the experiment they averaged a sub-five-minute-mile! The Daasanach were considerably slower, at about 8 minutes a mile. This suggests that speed, indeed, tends to influence which part of the foot you land on.)

Running this way reduces injuries.

It’s not at all clear that changing running form reduces injuries, according to the New York Times piece. In a study published last October, heel strikers were asked to temporarily switch to forefoot striking. The change wasn’t exactly a success.

... they found that greater forces began moving through the runners’ lower backs; the pounding had migrated from the runners’ legs to their lumbar spines, and the volunteers reported that this new running form was quite uncomfortable.

Still, when it comes to injuries, you might argue that if you have a strong spine and weak knees, you’d rather have your spine taking more of the impact from running and your knees less. Also, shifting weight forward could help, if for no other reason, because you may stress your knee joint differently and take some pressure off the areas of cartilage and bone that ordinarily take a pounding.

All possible, true. What’s more, Ron says that moving to a forefoot strike helped his bad knees, so it could be useful for some people. I’m skeptical though that it represents the “right” way to run.

Next time: The part of the “Runner’s Knee Cured” message I liked.

If Stretching Is Useless, Why Does It Feel So Good?

When it comes to stretching, I’m a skeptic about its purported benefits (see here, here and here for instance). I’m a huge fan of warming up before exercising. But stretching? Eh.

But, when you have knee pain, stretching your leg muscles often feels good. I was a bit of a “closet stretcher” myself during my recovery, long after I was convinced that stretching was a waste of time.

Why?

Because I was injured. When you’re injured, the hurt area feels tight and uncomfortable. It’s like your bad knee is smack dab at the center of an intense knot.

Partly that’s because of swelling in the joint, according to Doug Kelsey. A little swelling goes a long way. It inhibits muscle function, impairs movement, and leaves you eager to stretch everything from your IT band to hamstrings for relief.

I certainly did! Early on, my physical therapist prescribed quad stretches. My immediate reaction: “Wow! This is great. Why didn’t anyone tell me about these before?” But a stretched muscle eventually contracts and, sadly, I discovered that the window of relief from stretching began shrinking. (Note: In Paul Ingraham’s long essay on the subject, he notes that it has been shown to take at least 20 minutes of sustained stretching to actually improve range of motion. Try doing that every day for all the muscles you want to stretch, and you may find you need to switch to a part-time job just to get all your stretching in).

So, you must be thinking, I gave up stretching after learning all I did. Wrong! Occasionally, I still stretched during the later stages of my recovery. Again, it felt good. Plus, in the back of my mind, I was always thinking, “Hey, what if I’m wrong? At the very least, it can’t hurt.” (Which is true, I believe, for most stretches if you do them gently enough.)

Fast forward to today. My knees are fine. And I’m back to being the same old Richard as before my go-round with knee pain: a slender, fairly fit person with very little flexibility. (I’m almost the opposite of double-jointed, whatever that is.) And I never stretch.

Should you stretch? If it feels good and isn’t hurting your knees, and you want to, I see no reason why not to. Go for it! My sole reservation would be this: If you have only 30 minutes a day, say, for activities related to knee rehab, and you’re spending 10 of those minutes on an elaborate routine of stretching, I’d hit the rethink button (note: this isn’t the same as the reset button, but it’s close :)).

Between 10 minutes of stretching and 20 minutes of easy walking, and 0 minutes of stretching and 30 minutes of easy walking, I know which I’d choose, in a heartbeat. What about you?