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Posts Tagged ‘injuries’

Stress fractures: is it weak bones or muscles?

October 23rd, 2011

A new study from researchers at the University of Calgary, published in the November issue of Medicine & Science in Sports & Exercise, looks at bone quality and leg muscle strength in a group of 19 women who have suffered stress fractures in their legs, and compares them to a group of matched controls. The basic results:

  • the women who got stress fractures had thinner bones;
  • at certain key locations, the quality of the bone was lower in the stress fracture group;
  • the stress fracture group also had weaker leg muscles, particularly for knee extension (lower by 18.3%, statistically significant) and plantarflexion (lower by 17.3%, though not statistically significant).

Now, this sounds very similar to the results of a University of Minnesota study published a couple of years ago. Here‘s how I summed up the conclusions reached by those researchers:

What’s interesting, though, it that the bone differences were exactly in proportion to the size of the muscles in the same area, and there was no difference in bone mineral density. What this suggests is that the best way to avoid stress fractures is to make sure you have enough muscle on your legs — presumably by doing weights and (it goes without saying) eating enough.

What I don’t understand is that, in the new Calgary study, even though they mention the Minnesota study repeatedly in their discussion, they don’t discuss at all this idea that it’s the lower muscle strength that dictates the reduced bone size and thus the stress fracture risk — even though that was the primary conclusion of the Minnesota study. Instead, they say “the role of muscle weakness in [stress fractures] is unclear from previous studies,” and suggest that weaker knee extension might change running form to produce a “stiffer” running stride or somehow alter the direction of forces on the bone during running — both of which seem like unnecessarily complex and speculative ideas compared to the straightforward link between muscle strength and bone strength.

It’s entirely possible that I’m missing something here, because the paper is quite complex. But what I take away from it is, once again, that strengthening your legs is likely (though not yet proven in a prospective trial) to reduce your stress fracture risk.

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Sports medicine: evidence-based or sales-based?

September 6th, 2011

Great article by Gina Kolata in the New York Times on the challenges facing sports medicine doctors, and lack of evidence-based medicine that sometimes results:

[...] Patients “see a high-profile athlete and say, ‘I want you to do it exactly the same way their doctor did it,’ ” said Dr. Edward McDevitt, an orthopedist in Arnold, Md., who specializes in sports medicine.

The result is therapies that are unproven, possibly worthless or even harmful. There is surgery, like a popular operation that shaves the hip bone to prevent arthritis, that may not work. There are treatments, like steroid injections for injured tendons or taping a sprained ankle, that can slow the healing process. And there are fads, like one of Ms. Basle’s treatments, P.R.P., that soar in popularity while experts debate whether they help.

All this leads Dr. Andrew Green, a shoulder orthopedist at Brown University, to ask, “Is sports medicine a science, something that really pays attention to evidence? Or is it a boutique industry where you have a product and sell it?”

“For a lot of people it is a boutique business,” he said. “But are you still a doctor if you do that?”

The article focuses on platelet-rich plasma (PRP) therapy, since it’s a perfect example of the hype-before-evidence phenomenon that’s so common in sports medicine. Kolata discusses the mishmash of conflicting evidence, and the reasons the treatment seems plausible. But she also points out the inevitable conflicts of interest from some of the scientists whose evidence is used to support PRP:

They included Dr. Allan Mishra, an orthopedist in private practice in Menlo Park, Calif., who is supported by and gets royalties from one of the P.R.P. equipment makers, Biomet, and is on the board of directors and owns stock in another company, BioParadox, which is exploring the treatment for cardiovascular disease.

Dr. Mishra says more research is needed but offers the treatment for a variety of injuries. His Web page includes a TV news video that claims P.R.P. cured a Stanford football player, James McGillicuddy, with a torn knee tendon. On the program, Dr. Mishra says that, in general, 90 percent of the patients he treats “get better and stay better” after the treatment.

Wow, 90 percent success rate! Too bad he didn’t publish those results, because that’s not what any of the studies say. It sounds more like he “has a product and is selling it” — and unfortunately, that’s all too common with “breakthroughs” in sports medicine and physiotherapy.

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Relative injury risk of cycling, walking, driving and motorcycling

April 15th, 2011

Monday’s post on whether helmets encourage risky behaviour sparked a rather spirited discussion in the comments section. One of the louder claims was that, by choosing to write an article about bike helmets, I was making an implicit and unwarranted assumption that biking is more dangerous than, say, walking.

It’s an interesting question: is cycling more any more dangerous than walking? I went to look for some data. This is the first paper I found on Pubmed. I don’t know if it’s representative; I didn’t do a comprehensive search, and I’m under no illusion that this data will change anyone’s mind. Nonetheless, it’s data, from a paper published last fall in BMC Public Health. Researchers examined records from New Zealand’s Mortality Collection and National Household Travel Surveys to determine the incidence of injuries for several different survey periods. Here’s what they found for the most recent period, 2003-7 (the full paper is freely available at the link above, if you want to see the rest of the data):

Activity / Total injuries per year / Injuries per million hours spent travelling

Cyclists / 682 / 30.74

Car/van driver / 1714 / 2.10

Car/van passenger / 1086 / 2.89

Motorcyclist / 784 / 107.64

Pedestrian / 471 / 2.38

[UPDATE April 19: I've closed comments on this post, as I think we've reached a point of diminishing returns. Thanks to everyone for their contributions!]

Helmets, head injuries and “risk homeostasis”

April 11th, 2011

This week’s Jockology article in the Globe and Mail takes a look at helmets and the slippery concept of “risk homeostasis” — the idea that wearing protective equipment will cause you to take more risks and cancel out any safety benefits:

The message that Mikael Colville-Andersen offered to his audience at the TEDx conference in Copenhagen last November isn’t what you’d expect from a cycling advocate who travels the world promoting urban bike use.

“There are actually scientific studies that show that your risk of brain injuries is higher when you’re wearing a helmet, and that you have a 14-per-cent greater chance of getting into an accident with a helmet on,” he said. “These are not things that we hear about too often.”

With hockey head shots in the news, and revelations that ex-players like Bob Probert suffered from a form of brain damage called chronic traumatic encephalopathy, head protection is a hot topic. But Mr. Colville-Andersen’s controversial anti-helmet crusade offers a reminder that technology and equipment, on their own, can’t keep us safe. We have to consider the underlying factors that influence our risk-taking decisions – and those of the people around us… [READ THE WHOLE ARTICLE]

UPDATE April 11: Lots of e-mails and comments on the Globe site: this is clearly a controversial topic, so I’d like to expand on a couple of points. The truth is that I started working on this article with the idea of presenting the counterintuitive research that Mikael Colville-Andersen discusses in his TEDx talk, showing why helmets are actually a bad idea. But when I dug into the literature, I found that the picture was much more complicated than the way he portrayed it.

There are really two separate questions: physics and public policy. The first is fairly straightforward and asks whether, in the context of certain types of mishaps that sometimes occur on bicycles, a helmet will significantly reduce the severity of your injury. In the lab, we can clearly see that helmets can mitigate the effects of certain impacts. It’s much harder to show that this is the case in the real world, because we can’t have access to “controlled” scenarios of people going head-over-heels with and without helmets. And statistical studies of injury rates are hindered by all sorts of very serious limitations (e.g. we don’t actually know how cycling rates change, let alone traffic conditions, road surfaces, cycling skills, etc.)

Now, one could argue (as many people do) that the lack of crystal-clear epidemiological evidence of reduced cycling-related head injuries is PROOF that helmets don’t work. This is specious. Just because something is difficult to prove doesn’t mean that it’s not true. We can debate where the burden of proof should lie, but my personal assessment of the laboratory data, in combination with the admittedly circumstantial epidemiological data, is that there are certain situations in which I’d be very glad to have a helmet on my head. I certainly accept that other people might look at the same data I looked at and decide that helmets aren’t worthwhile – after all, risk calculation is a personal thing. But those who claim that it’s “proven” that helmets make no difference whatsoever in the context of individual accident scenarios are simply delusional, in my opinion.

Where Colville-Andersen is more convincing is in his public policy arguments, rooted in some of the factors I discuss in the article (risk homeostasis, safety in numbers, etc.). There have been dozens and dozens of studies on cycling injury rates and how they changed (or not) with the introduction of helmet campaigns and laws. My impression after reading through many of these studies: there are more studies supporting the efficacy of helmets than there are null studies, but the results are surprisingly weak and the overall conclusions are equivocal at best. All of the studies are plagued by serious methodological challenges inherent in trying to study this question. There are certainly plenty of studies that forcefully conclude that helmets are either good or no good, and plenty of people who cherry-pick those results in order to claim that the debate is settled one way or the other. But if you open both eyes and look at the totality of the data, I don’t believe there’s enough evidence to reach a conclusion either way.

And that leaves us with some interesting policy debates. If the overall effect of helmets is weak at best, are we justified in imposing a helmet law on children? How many cases of brain damage in Ontario would have to be avoided each year to make such a law worthwhile? One? Ten? 100? 0.1? These aren’t science questions, they’re policy questions. They’re worth debating – certainly, I’m more open to the idea of scrapping helmet laws than I would have been before watching Colville-Andersen’s talk. But as I concluded in the Globe article: based on what I learned from going through all this literature, I’ll still be wearing a helmet when I bike.

Early rehab after knee surgery pays off

March 10th, 2011

Back in 2009, I wrote about the trend to move from passive rehabilitation to active rehabilitation — that instead of “RICE” (rest, ice, compression and elevation), we should think in terms of “MICE” (movement, ice, compression and elevation). In that light, I was interested to see a new Spanish study that tested when rehab should begin after knee replacement surgery. They took 300 patients and randomly assigned them to begin rehab either within 24 hours of surgery or 48 to 72 hours after surgery. The results were clear:

On average, those beginning treatment earlier stayed in hospital two days less than the control group and had five fewer rehabilitation sessions before they were discharged. An early start also lead to less pain, a greater range of joint motion both in leg flexion and extension, improved muscle strength and higher scores in tests for gait and balance.

Obviously they weren’t doing jumping jacks or anything like that on day one:

The post-operative treatment began with a series of leg exercises, breathing exercises, and tips on posture. By the second day walking short distances with walking aids was added, and in subsequent days this was built up towards adapting to daily life activities, such as beginning to climb stairs on day four.

Anyway, just thought it was an interesting data point — that even for something as major as a knee replacement, lying around and staying immobilized is no longer seen as the optimal way to promote healing.

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Swelling helps healing, so are ice and NSAIDs bad?

November 23rd, 2010

Lots more to come from the sports nutrition conference in Canberra, but first I just wanted to quickly put up a link to my article in today’s Globe about new research suggesting that swelling may help injuries heal faster:

Every weekend athlete knows the RICE rule for dealing with minor sprains and strains: rest, ice, compression and elevation, with the latter three tactics aimed at minimizing inflammation.

But a study published last month by researchers at the Cleveland Clinic adds to growing evidence that swelling actually plays a key role in healing soft-tissue injuries. The result is a classic tradeoff between short-term and long-term benefits: reducing swelling with ice or anti-inflammatory drugs may ease your pain now, but slow down your ultimate return to full strength.

“This whole discovery has really thrown into question all of our traditional approaches to treating injuries,” says Greg Wells, a University of Toronto exercise physiologist who works with national-team athletes at the Canadian Sport Centre. [READ THE WHOLE ARTICLE...]

Another blood spinning study finds no improvement in Achilles tendons

November 15th, 2010

Actually, the title isn’t quite true — this is a just new wrinkle on the same Dutch study reported earlier this year that found no difference between platelet-rich plasma injections and placebo (saline) injections for 54 patients with chronic Achilles tendinopathy. The new paper, just published online at the British Journal of Sports Medicine, presents further data from this experiment: in addition to the previously reported pain scores (which, admittedly, are a bit wishy-washy and subjective), they used “ultrasonographic tissue characterization, a novel technique which quantifies tendon structure.”

Basically, they used ultrasonic imaging combined with computer image recognition to get an automatic (i.e. objective) measure of tendon health. The results: scores improved for both PRP and placebo (note that the subjects were also doing a rehab regime involving eccentric exercises during the study), but there was no significant difference between the groups.

Given the results presented earlier, this isn’t a big surprise — and of course, certainly isn’t proof that PRP doesn’t work in any context. But it’s another reason for skepticism. As the authors conclude, “these data argue against clinical use of this form of PRP in present clinical practice.”

Biomechanics for performance and injuries

November 1st, 2010

My Jockology column in today’s Globe and Mail takes a look at the growing use of biomechanics technology by elite and recreational athletes, both to enhance performance and address injury problems. The two guys I spoke to were Dana Way, the Winnipeg-based biomechanics expert who travels with the Canadian track team, and Reed Ferber, who runs the University of Calgary’s Running Injury Clinic and has been rolling out a 3-D gait analysis system at clinics in western Canada.

[...] In typical laboratory “motion-capture” systems, small reflective markers are affixed to the athlete’s body at key points such as joints and extremities. Video cameras connected to a computer record the motion of these markers, and use the data to draw a stick-figure that duplicates the essential features of the athlete’s motion.

While traditional systems used a single camera to capture motion in two dimensions, the latest systems use multiple cameras to create a three-dimensional model. Major League Baseball’s Boston Red Sox, for example, are using a 20-camera system to analyze the throwing motion of their pitchers.

At the University of Calgary’s Running Injury Clinic, biomechanist Reed Ferber has been using an eight-camera system with 20 reflective markers to analyze the running gait of his patients and research subjects. But he’s found that for the 3-D gait analysis systems he’s started installing at sports clinics across the country, three specially designed cameras are sufficient. [READ THE WHOLE ARTICLE...]

The accompanying graphic, by the Globe‘s Trish McAlaster, does a nice job of showing how the 3-D gait analysis works:

lf-jockology-biomechanics-graphic

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Achilles tendons, platelet-rich plasma and Megan Wright

October 11th, 2010

Today’s Globe has my article on new approaches to treating and preventing Achilles tendinopathy, including platelet-rich plasma therapy, a.k.a. blood spinning. Since I’m in Delhi, I had a chance to speak to the experts here with the Canadian team, and to Megan Wright (2008 Olympic 5,000-metre finalist who missed most of 2009 with Achilles tendon problems):

… In some cases, though, tendinopathy doesn’t respond to conservative treatment. In the months before and after the Olympics, Ms. Wright tried icing, acupuncture, sleeping in a “night splint” and “kinesio taping” – applying special tape along the length of the calf to relieve strain on the tendon. She even tried intramuscular stimulation, sometimes called “deep needling,” in her calves – a procedure that, as the name suggests, involves sticking needles deep into the calf muscle.

Finally, she turned to platelet-rich plasma. Since tendons have a very poor blood supply (unlike muscles), minor tears and inflammation tend to heal slowly. PRP therapy involves drawing a small amount of the patient’s own blood, spinning it in a centrifuge to concentrate the most useful components (the platelets) and reinjecting this concentrated plasma at the injury site. The platelets then release various “growth factors” that stimulate the body’s natural healing response… [READ THE REST OF THE ARTICLE]

Wright races tomorrow night against a tough field, including the inevitable trio of Kenyans. I’ll be live-tweeting the race, which is scheduled to start at 11:20 a.m. Eastern time, at @sweatscience.

Inflammation is needed to repair injured muscle

October 9th, 2010

There’s growing recognition that anti-inflammatory drugs aren’t always the best response to muscle soreness or injury. In that light, the press release accompanying a new study in the FASEB Journal is overstating things when it says “the study shows for the first time that inflammation actually helps to heal damaged muscle tissue, turning conventional wisdom on its head.” Still, the results are interesting:

The research report shows that muscle inflammatory cells produce the highest levels of IGF-1 [insulin-like growth factor-1], which improves muscle injury repair. To reach this conclusion, the researchers studied two groups of mice. The first group of mice was genetically altered so they could not mount inflammatory responses to acute injury. The second group of mice was normal. Each group experienced muscle injury induced by barium chloride. The muscle injury in the first group of mice did not heal, but in the second group, their bodies repaired the injury.

The paper itself makes it clear that researchers already knew that inflammation was important to muscle repair, but the mechanism (i.e. the role of macrophages in producing IGF-1) was unclear. So does this mean that anti-inflammatories are a bad idea after muscle injury? Not necessarily — too much inflammation can still cause problems (for reasons that aren’t entirely clear to me). What the authors propose is that, when a muscle injury is being treated with anti-inflammatories, it may make sense to also administer supplemental IGF-1 to compensate for what the anti-inflammatories are blocking.