Sunday, October 28, 2012

Beating Knee Pain: Do You Have a Plan?

A while ago, while working out at the gym, I heard a canned announcement over the PA system designed to sell the services of the on-site trainers.

“Do you have a plan to get fit?” a pleasant voice asked.

At the time, it struck me as deeply ironic.

We accept the need for a plan to build muscle strength and improve cardiovascular fitness. But that’s child’s play compared with managing knee pain, with an eye toward actually getting better. If the former requires a half-page plan, the latter demands something like three pages of detailed notes.

Yet how many knee pain sufferers are there who just muddle along, day to day, and never try to plot a path toward healing?

Broadly, what should go into a plan for beating knee pain?

I think it helps to start with a realistic appraisal of your condition. And be willing to be humbled. You may want to start out walking three miles a day; your knees may quickly tell you that they can only do half that much comfortably.  

Also, of course, you have to decide what your regimen will consist of, day to day, in terms of walking/cycling/swimming/other joint-friendly activities, and how much of each.

Not too hard so far -- rather like designing a workout program in fact. Here’s where it gets tough. You need to be able to adjust on the fly, and play medical detective.

Example: You wake up one morning during week five and your bad knee is really stiff. Oh no! What do you do? You have to be able to ease off for a few days -- or even a few weeks, if needed. Also you need to try to figure out what may have caused the stiffness, so you can avoid doing that again.

So you want to keep some kind of knee journal, to make sure your plan is working and help guide you in revising your plan as your knee gets stronger (yay!) -- and also help you figure out what went wrong when your knee gets worse (ugh!).

To beat knee pain, I’m convinced you need a thorough, though flexible, plan. It may sound challenging. But the rewards are great if you succeed!

Sunday, October 21, 2012

Yet More Proof Your Doctor Isn’t Infallible

One of the first criticisms I got about Saving My Knees went like this:

“This is a lousy book. All he does is complain about how all his doctors and physical therapists are wrong and I can’t tell if he got better anyway.”

(By the way, if anyone else is similarly puzzled on that last point, I can unequivocally state that yes, I got a whole lot better. My knees are fine today.)

Read between the lines, and the reviewer appears to be annoyed that I have the temerity to suggest there’s something wrong with the expert advice I was given on treating knee pain.

Why such a harsh reaction?

I think among certain people there is a reflexive, total deference to the opinions of “experts,” even though what is accepted as truth by one generation of experts may be soundly rejected by the next. (History is full of examples; in Saving My Knees I mention the once widespread medical practice of bloodletting to cure a host of ailments, which has been debunked as nonsense.)

Today I’m going to show you that your doctor is very much human -- and not an infallible expert at all -- with a bit of math. It’s taken from Fooled by Randomness by Nassim Taleb, who himself has borrowed the anecdote from Randomness by Deborah Bennett.

Medical doctors were given this problem to solve:
A test of a disease presents a rate of 5% false positives. The disease strikes 1/1,000 of the population. People are tested at random, regardless of whether they have the disease. A patient’s test is positive. What is the probability of the patient being stricken with the disease.
(If you want to try to figure it out yourself, go ahead. I start to disclose the solution immediately below.)

Most doctors -- more than four out of five -- got this wrong. They answered 95% because they focused solely on the accuracy rate. But the question being asked isn’t, “How accurate is the test?” The question, stated more fully, is “What’s the probability the patient has a somewhat rare disease if a test that’s wrong 5% of the time says he does?” And the answer to that question is very different: less than 2%.

Taleb explains how he arrives at that figure:
Assume no false negatives. Consider that out of 1,000 patients who are administered the test, one will be expected to be afflicted with the disease. Out of a population of the remaining 999 healthy patients, the test will identify about 50 with the disease (it is 95% accurate). The correct answer should be that the probability of being afflicted with the disease for someone selected at random who presented a positive test is the following ratio: number of afflicted persons/number of true and false positives. Here, 1 in 51.
Got that? The difference between the right answer and the most commonly mistaken one is very significant. It’s the difference between “you almost surely have the disease” and “you almost surely don’t have the disease.”


There are a few points worth making here. The less interesting one, to me, is that doctors often can be mistaken.

The point that I find more interesting (and empowering) is that you don’t have to be a medical school graduate and a practicing physician to analyze information about medical conditions (claims, studies, empirical evidence) and come to conclusions that, in some cases, may be superior to those held by so-called experts.

What’s more, when it comes to your bad knees, you do know more than your doctor on one very important subject: how your knees behave (what they like and don’t like, what causes pain, etc.)

So if a doctor says, “Ah, your knees will never get better” (which is what I was wrongly told), remember: doctors can be wrong -- very wrong.

After all, four out of five missed the correct answer to a basic statistics problem. :)

Extra credit: Did you notice Taleb's approach to solving the problem? Out of a population of 1,000, he removed the person who has the disease (remember, it strikes 1 out of 1,000 people), then calculated that 5% of the remaining 999 were false positives (49.95). So the chance of having the disease is 1/50.95 or 1.9627%.

Alternatively, you could apply the 5% rate of false positives to the population of 1,000, resulting in 50 people who wrongly test positive for the disease, then add the one person who actually has it. So the chance of having the disease this way is exactly 1/51 or 1.9608% -- a bit different.

So, given the information as laid out in the problem, which answer is correct, and why?

Note: The difference in the results from the two approaches is trivial, so you may think it hardly matters which one is correct. While that's true for this example, it wouldn't be for another, say where 30% of the population has some disease and the test has a rate of say 20% false positives.

Sunday, October 14, 2012

Glucosamine Sulfate and the Placebo Effect

I was doing some housekeeping recently on the computer, cleaning out old files, when I came upon this:
In a landmark meta-analysis of 10 placebo-controlled trials of glucosamine and chondroitin that researchers said should “close the book” on whether these popular supplements actually help arthritis sufferers, Peter Juni, MD, of the University of Bern in Switzerland, and colleagues concluded, ”Our findings indicate that glucosamine, chondroitin, and other combinations do not result in a relevant reduction of joint pain or affect joint-space narrowing compared with placebo … We believe it unlikely that further trials will show clinically relevant benefit of any of the evaluated preparations.”
The article isn’t that old (from last year), but it did manage to transport me back to the summer of 2007, and the early days of my struggle with knee pain.

My very first orthopedist introduced me to glucosamine. At the time, I was afraid I had some sort of damage inside my knee joints. I liked the idea of rebuilding my cartilage using natural supplements that supply a key ingredient for ensuring the tissue’s strength and elasticity.

By 2007, glucosamine had been the subject of a number of flattering books and articles. A decade earlier, in 1997, New York Times health columnist Jane Brody spurred sales after writing about how glucosamine and chondroitin supplements helped her arthritic dog. She then thought, “Hey, what if they can help my arthritic knees too?”

According to this Web site:
She limped, had difficulty with stairs, and with playing tennis ... After a year of taking glucosomine sulfate and chondroitin sulfate she is not totally pain free but neither is she disabled. Jane Brody now plays singles tennis two to four times a week, skates four or five times a week, and takes brisk 3 miles walks.
As for me, sadly, glucosamine had no perceivable effect on my knee health, as I note in Saving My Knees. After many months, I stopped taking it, convinced it was doing nothing. Eventually, I got around to investigating why it had done nothing for me.

That glucosamine is vital for ensuring healthy cartilage isn’t in dispute. Also, it’s been shown in studies to have a salutary effect, when additional amounts are introduced to cartilage sitting in petri dishes. But the glucosamine story goes awry at this point: in the real world, your knee cartilage isn’t conveniently lying in a petri dish -- you have to swallow tablets of the supplements, which unfortunately (as at least two studies have shown) get pretty well whacked apart by the liver.

An insignificant amount of glucosamine winds up making its way into your knee joints (here's one study that found that: "Low Levels of Human Serum Glucosamine After Ingestion of Glucosamine Sulphate Relative to Capability for Peripheral Efffectiveness," Annals of the Rheumatic Diseases 2006).

So why do so many people exult about the benefits of glucosamine? The closer you look, the more the answer appears to be the placebo effect. Still, what’s wrong with a placebo? Less pain is less pain, after all. I think this is a valid point, but a big caveat should accompany it.

The reason for that caveat I can illustrate with the story of my “Superman pill.”

A man seeks relief from chronic back pain. I give him a bottle of “Superman pills,” which (known only to me) are nothing more than super placebos. Anyone who ingests one feels a lessening of pain and believes he or she has a healed back as strong as Superman’s.

What happens next? Well, the back pain sufferer thinks he’s cured, decides to help his brother move a wood stove up three flights of steps (or something equally ambitious), and ends up really damaging his spine.

That, to me, is the big danger of the placebo effect: thinking you’re actually healed (or are healing) when you haven’t (or aren’t).

Which brings us back to Jane Brody. What the Web site I directed you to earlier doesn’t say (even though it claims to have been updated in 2011!) is that Brody had a double knee replacement, apparently in 2004 (which she discusses, in frank detail, here). Did taking glucosamine cause her to over-exert herself? Did she wrongly believe she could indulge freely in skating, tennis playing and brisk walking because the glucosamine supplements were busily repairing her bad cartilage?

I don’t know. But her story is certainly a cautionary tale for glucosamine enthusiasts.

Saturday, October 6, 2012

Do Flat Feet Cause Bad Knees?

This article would have you think so.

I was initially drawn to the story by the breathless tease on the top:
Having flat feet can destroy your knees: Many think wonky feet are a joke -- but the effects are often crippling.
Granted, this isn’t the New England Journal of Medicine. It’s Britain’s Daily Mail. Still, I was curious how flat feet could destroy a pair of perfectly good knees.

The story is that of Arti Godkhindi, 34, who describes her knees as “chronically bad.” The 5-foot-7-inch IT consultant weighed about 10 stone (140 lbs.) and got pregnant and gained two stone (28 lbs.) -- or 20 percent of her original weight. (For me, that would be like going from 175 lbs. to 210!)

During her pregnancy, she walked an hour a day to stay fit. After her daughter was born, she had trouble shedding her excess weight, so she joined a gym. “I started gently,” she says, then adds, “But as soon as I tried to do any running or stretching, I felt this excruciating pain on the inside of both knees.”

So she had an MRI done, which showed tears in the meniscus (pads of cartilage in the joint that absorb shock) in both knees. She was diagnosed with patellofemoral pain syndrome (which is pretty much a worthless diagnosis, I found: see here).

What’s the cause of her “permanent, disabling knee pain,” according to this article?

Her flat feet! Because, we are told, people like her (the quotes are from her doctor):
“... may have been living with faults in the way they walk, such as overpronation — also known as flat feet (which cause the feet to roll inwards) — or supination, where the feet roll outwards. They manage perfectly well until there is weight gain.”

Flat feet or other faults cause you to carry your weight through the wrong part of the foot, he [Dr. David Jones] explains, setting off a chain reaction upwards through the body.

“Where the knee cap connects with the thigh bone or femur, there is a V-shape groove, to help the knee cap glide up and down.

“If your feet roll inwards, the knee cap doesn’t move smoothly through this groove. We call this bad tracking and, over time, it leads to damage of the cartilage and pain.”
This is a conventional, structuralist sort of explanation for knee pain. However, as I’ve noted before, maltracking kneecaps may not be a significant predictor of knee pain (according to this study). And orthotics (which are recommended for flat feet sufferers later in the article), may be useless anyway, according to the New York Times ("The idea that they are supposed to correct mechanical-alignment problems does not hold up").

(Note: It is a good idea, of course, to wear proper-fitting shoes with good cushioning; that's common sense.) 

So, if I’m Arti’s flat feet, I’d start looking for a good defense attorney. After all, her Dad also has flat feet -- but no knee pain. What else may have caused her knee pain?

She gained a lot of weight during her pregnancy. Weight gain should always be a suspect in a knee pain whodunnit, whether you have flat feet or perfect arches.

Changes to her body during pregnancy (softening of muscles and ligaments, altering biomechanics, e.g.), as mentioned in the article, may have predisposed her to knee pain.

Her efforts to lose weight after the pregnancy should be strongly considered as possible culprits. Did she go from being fairly inactive to suddenly active? It wouldn’t need to take much either -- notice how a reference to running (“As soon as I tried to do any running or stretching, I felt this excruciating pain ...”) is quietly slipped into a quote.

But that’s huge! Running can be very hard on joints, especially if you’ve never done it before or are resuming the activity after a long layoff.

I’m not saying her flat feet are necessarily totally blameless. But I suspect their role in this misfortune has been much overstated.