The tensor fascia latae (TFL) muscle.
It’s a common idea in musculoskeletal medicine that muscles can be “dysfunctional,” boosting injury risk over time, and otherwise letting us down. Dysfunction of the tensor fascia latae (TFL) muscle is one of the more usual suspects, often blamed for contributing to several hip and knee injuries and issues, but mostly iliotibial band syndrome, greater trochanteric pain syndrome, and patellofemoral syndrome.
Besomi et al. reviewed seventeen studies of the TFL in people both with and without several conditions (in addition to the above, hip joint arthritis and knee ligament tears). Eight of the studies were of the size of the TFL (“structure”), and ten were studies of its electrical activity while contracting (“activation”).
They found a handful of minor, uninformative differences in these measurements — which is utterly unsurprising. There are a few reasons why I wouldn’t ever expect such studies to shed much light on anything.
What is this “dysfunction” you speak of?
Above all, muscle “dysfunction” is a really poorly defined concept. Activation and size are just a couple things about a muscle that we can easily measure, “looking where the light is,” but without dramatic differences they are unlikely to tell us anything about how well the muscle is working. There are other ways that a muscle could plausibly be dysfunctional which were not considered by these studies at all.
Also, some of these studies were looking for more implausible links with other injuries. It’s a bit of a reach to blame the TFL for anything at all, but knee ligament tears? Hip arthritis? Come on. I would be shocked if those conditions were TFL-sensitive.
Even when the research flashlight is aimed at a condition with a more plausible link — like Baker et al did, studying the TFL-ITBS link specifically — there’s hardly a smoking gun there either. They found essentially nothing.
Besomi et al reasonably concluded that the “common clinical assumptions” about the TFL’s role in injury are “not well investigated and poorly supported.” Indeed! These kinds of ideas have always just been speculative, just professionals spitballing about how muscles and joints work. Most of them have yet to be studied at all, let alone well.
There is maybe one slightly useful thing this study can tell us: apparently there is nothing terribly obvious wrong with the TFL in people with these injuries, or it probably would have shown up in the seventeen studies reviewed. But that’s kind of like saying “if bigfoot was as tall as King Kong, he would have been found ages ago.”
Bottom line: No one really has any idea if there’s any such thing as a glitchy tensor fascia latae, let alone whether it causes injuries, and Besomi et al does not shed any significant light on this topic.
I will be doing more study summaries like this. Several readers have told me recently that what they value most about my work is translating the science for them, either because they don’t have the skills, or the time, or both. So I am going to focus more on that.
This citation is featured in a new chapter about TFL dysfunction to my book on iliotibial band syndrome, the condition to which the TFL seems most relevant. There’s some additional ITBS-specific discussion there. And Besomi et al will probably get cited in my patellofemoral syndrome book as well.
Besomi M, Maclachlan L, Mellor R, Vicenzino B, Hodges PW. Tensor Fascia Latae Muscle Structure and Activation in Individuals With Lower Limb Musculoskeletal Conditions: A Systematic Review and Meta-Analysis. Sports Med. 2020 Jan. PubMed #31898217 ❐
Baker RL, Souza RB, Rauh MJ, Fredericson M, Rosenthal MD. Differences in Knee and Hip Adduction and Hip Muscle Activation in Runners With and Without Iliotibial Band Syndrome. PM R. 2018 10;10(10):1032–1039. PubMed #29705166 ❐