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Wonky knees 

 •  • by Paul Ingraham
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Weekly nuggets of pain science news and insight, usually 100-300 words, with the occasional longer post. The blog is the “director’s commentary” on the core content of a library of major articles and books about common painful problems and popular treatments. See the blog archives or updates for the whole site.

Pal et al. found that one kind of wonkiness (high kneecaps) was fairly strongly associated with another kind (bad tracking), and that this kind of thing was more common in people with knee pain. This contradicts my bias and I’m a bit skeptical. The researchers were probably biased in the other direction, and expected to find abnormalities correlating with pain. They didn’t measure all that many knees, just 37 people with pain, and it’s easy to find what you expect in small batches of data. They don’t report just how much higher kneecaps were in the abstract, which would be natural to do if it were an impressive number, so I suspect it’s not an impressive number. Even if the correlation is real, it doesn’t tell us anything about cause (maybe misbehaving kneecaps cause pain, or maybe knee pain causes kneecaps to misbehave). Almost half their subjects had no abnormalities at all, which is consistent with other studies (Herrington et al) showing that you can find a roughly even mix of abnormalities in everyone, whether they have pain or not.

So this data does not change my basic position: biomechanical oddities may be a causal factor in some cases of knee pain, but probably not a major factor, or a majority of cases.

“Patellar maltracking is prevalent among patellofemoral pain subjects with patella alta: An upright, weightbearing MRI study”
Pal et al. Journal of Orthopaedic Research. Volume 31, Number 3, 448–57. Mar 2013.