Oops! I thought the science of this big tendon and its movements was settled. Specifically, I had high confidence that it does not move back-and-forth across the side of the knee (causing IT Band syndrome). My confidence was based on compelling evidence that it can’t move like that — an anatomical impossibility, or near enough. And so debunking “friction” in runner’s knee became one of the mythbusting pillars of my extensive writing on that topic.
It all seemed so clear! I really never expected any controversy on this topic.
And yet there is. Science seems determined to be perpetually unfinished.
Iliotibial band syndrome is a stubborn kind of tendonitis in runners, affecting the enormous iliotibial tract or IT band that runs down the thigh and over the side of the knee. For decades, everyone mostly assumed that the IT band was irritated by rubbing back and forth over a bump of bone on the side of the knee, the lateral epicondyle, and so it was often called a iliotibial band friction syndrome.
That old version of the IT band story was challenged about a decade ago by Fairclough et al,12 a dissection study showing that the IT band is actually firmly anchored to the bone it is supposedly rubbing over. Rather than rubbing, it seemed more likely that the IT band was simply compressing the tissue underneath it over and over again, and any appearance of movement was an illusion created by a “wave” of tautness moving through the fibres. This seemed like a decisive change in how IT band should be described: for most people paying attention to it, myself included, Fairclough’s paper more or less put the idea of “friction” in ITBS out to pasture. Friction became a myth to be busted, and I busted it.
But a 2013 ultrasound study by Jelsing et al has set the pendulum back in motion again, back towards friction.3 The science of this is no longer settled.
Fairclough et al. basically made an assumption that the IT band cannot move back-and-forth, based on the anatomy — a reasonable assumption, perhaps, but an assumption nevertheless.4 Jelsing et al. decided to actually properly check what happens in living subjects using ultrasound. Why not?
“In our opinion,” they write, “the well-documented fascial attachments of the ITB to the lateral femur may limit anteroposterior ITB motion but do not preclude such motion.”
And, of course — because science is just like this — they found that the IT band does move.
The distance from the anterior fibers of the ITB to the apex of the lateral femoral epicondyle decreased from the fully extended to 30° and the fully extended to 45° positions. … We have clearly documented that the ITB does in fact move anteroposteriorly relative to the lateral femoral epicondyle within the functional ranges of knee flexion-extension.
Fascinating. How inconvenient for me! So much for all my tidy, confident debunking of the friction myth.
The study was straightforward: they used ultrasound to carefully examine 40 knees in 20 healthy recreational runners (five men and 15 women). They measured the distance between the forward edge of the IT band and the lateral femoral epicondyle, through the first 45˚of knee flexion, and found that it moved backwards .71cm on average.5
This evidence is inherently simple and compelling. I’ve read the entire paper carefully, twice now, and it’s hard to find much fault with it. It’s well-written and covers all the bases. The authors candidly acknowledge a few notable weakness, but none are obvious deal-breakers.6 The biggest is that “we did not specifically determine the reliability of our measurements or their accuracy relative to a reference standard.” Which is related to my own main concern…The tone of the whole paper is quite reasonable, fairly represents all key relevant points & generally strikes me as an earnest attempt to discover the truth & not just prove someone else wrong.
The results depend completely on the expert observations of a single ultrasound expert, who might have been gunning for Fairclough and found what he wanted to find (evidence that Fairclough was wrong). Like all imaging technology, ultrasound really does require expertise to correctly interpret. The images are cryptic to non-experts. But experts can have selective perception too, and the history of science is chock-a-block with good examples of that.
Highlighting the general problem with interpreting ultrasound images: they knew they really need to look at the back edge of the band (more on this below), and yet it was so difficult to actually see that they were only able to measure it in 4 of 20 patients.7
And yet I doubt that’s actually what happened here. The tone of the whole paper is quite reasonable, fairly represents all key relevant points, and strikes me as an earnest attempt to discover the truth and not just to prove someone else wrong. The results certainly need to be replicated, but I wouldn’t waste my money betting against it. I suspect another examiner will find the same thing.
The authors themselves thoroughly covered one of my own chief concerns: the possibility that it only looks like the IT band is moving, much as Fairclough et al. originally suggested.
Although these data clearly showed that the anterior ITB moved relative to the LFE, we did consider the possibility that this motion may not represent translation [sliding across the LFE]. It would be possible for the anterior fibers of the ITB to move closer to the LFE as a function of ITB tightening due to increased tension.
This is why they tried to look at the back edge of the band as well as the front. Was the whole thing moving, both edges together? The edge was so hard to see in most people they could only get data on it from four subjects … but in those four, the back edge did move in tandem with the forward edge. And so:
Given that both the anterior and posterior fibers of the ITB moved posteriorly during knee flexion, it is reasonable to conclude that the ITB does translate to some extent over the LFE during knee flexion.
However, just because it moves does not mean there’s friction or that the movement is clinically significant. And may still not be “sliding” at all, but moving more like the swaying of seaweed anchored to rocks in shallow water. That is, it’s not “rubbing” back and forth so much as flexing to and fro — mostly eliminating the possibility of any significant friction. If the Jelsing and Fairclough can be reconciled, that’s probably how.
Adding more to the credibility of this paper, the authors graciously point out that “our findings are not necessarily wholly contradictory to those published by Fairclough and colleagues,” because the anchoring of the IT band to the underlying bone may indeed limit any rubbing motion, but without completely eliminating it.
Maybe that anchor is more secure in some people than others. Maybe that’s why some people get IT band syndrome — because the have looser IT bands at that location, and there’s more friction. Anatomical variation is the norm!
Obviously I am now going to have to reconsider and revise everything I’ve written about “friction” in IT band syndrome being a myth. However, I’m not going to quite rush out and reverse my position. The impact of this study is that the whole topic is now unsettled science, not settled in new place. I was confident in what I thought I knew. Now I just don’t know again, and that’s how I’ll handle it for now. I can live with the uncertainty. I don’t have much choice, obviously.
I am a science writer, former massage therapist, and I was the assistant editor at ScienceBasedMedicine.org for several years. I have had my share of injuries and pain challenges as a runner and ultimate player. My wife and I live in downtown Vancouver, Canada. See my full bio and qualifications, or my blog, Writerly. You might run into me on Facebook or Twitter.
— Added brief explanation of how Jesling might be reconciled with Fairclough: “just because it moves does not mean there’s friction….” Also, this content has now been integrated into Save Yourself from IT Band Syndrome!.
BACK TO TEXT
Iliotibial band (ITB) syndrome is a common overuse injury in runners and cyclists. It is regarded as a friction syndrome where the ITB rubs against (and 'rolls over') the lateral femoral epicondyle. Here, we re-evaluate the clinical anatomy of the region to challenge the view that the ITB moves antero-posteriorly over the epicondyle. Gross anatomical and microscopical studies were conducted on the distal portion of the ITB in 15 cadavers. This was complemented by magnetic resonance (MR) imaging of six asymptomatic volunteers and studies of two athletes with acute ITB syndrome. In all cadavers, the ITB was anchored to the distal femur by fibrous strands, associated with a layer of richly innervated and vascularized fat. In no cadaver, volunteer or patient was a bursa seen. The MR scans showed that the ITB was compressed against the epicondyle at 30 degrees of knee flexion as a consequence of tibial internal rotation, but moved laterally in extension. MR signal changes in the patients with ITB syndrome were present in the region occupied by fat, deep to the ITB. The ITB is prevented from rolling over the epicondyle by its femoral anchorage and because it is a part of the fascia lata. We suggest that it creates the illusion of movement, because of changing tension in its anterior and posterior fibres during knee flexion. Thus, on anatomical grounds, ITB overuse injuries may be more likely to be associated with fat compression beneath the tract, rather than with repetitive friction as the knee flexes and extends.
BACK TO TEXT
OBJECTIVES: The purpose of this study was to determine whether the iliotibial band (ITB) moves relative to the lateral femoral epicondyle (LFE) as a function of knee flexion in both non-weight-bearing and weight-bearing positions in asymptomatic recreational runners.
METHODS: Five male and 15 female asymptomatic recreational runners (10-30 miles/wk) aged 18 to 40 years were examined with sonography to assess the distance between the anterior fibers of the ITB and the LFE in full extension, 30° of knee flexion, and 45° of knee flexion. Measurements were obtained on both knees in the supine (non-weight-bearing) and standing (weight-bearing) positions.
RESULTS: The distance between the anterior fibers of the ITB and the LFE decreased significantly from full extension to 45° of knee flexion in both supine (0.38-cm average decrease; P < .001) and standing (0.71-cm average decrease; P < .001) positions. These changes reflect posterior translation of the ITB during the 0° to 45° flexion arc of motion in both the supine and standing positions.
CONCLUSIONS: Sonographic evaluation of the ITB in our study population clearly revealed anteroposterior motion of the ITB relative to the LFE during knee flexion-extension. Our results indicate that the ITB does in fact move relative to the femur during the functional ranges of knee motion. Future investigations examining ITB motion in symptomatic populations may provide further insight into the pathophysiologic mechanisms of ITB syndrome and facilitate the development of more effective treatment strategies.