Ipsilateral patterns of the rotational range of motion of the hip in healthy Japanese adults.
Heonoo Han, Akira Kubo, Kazuo Kurosawa and 5 others
PMID 27799692WHAT IT FOUND
222 healthy Japanese adults showed hip rotation patterns that differed by sex: males more often had external rotation greater than internal rotation, females more often had internal rotation greater.
Left and right sides did not differ. The difference was common, not proof of disease.
Key findings
01In 222 healthy Japanese adults, hip rotation patterns differed by sex: males had external rotation greater in 46.6% of hip joints, while females had internal rotation greater in 36.7%.
02There was no significant difference between left and right hip rotation patterns.
03When left and right patterns were combined, males had external rotation greater on both sides in 31.5%, and females had internal rotation greater on both sides in 25%.
STILL TO COME
How it was doneWhat they foundWhat it means for PTs
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What it does not show
The participants were healthy Japanese medical students with a mean age of 21.2 years, so the patterns may not apply to older adults, people with hip or spine problems, or other populations. The study measured rotation once and did not follow anyone or test treatment, so it cannot show that a hip rotation pattern causes pain, dysfunction, or injury, or that changing the pattern helps. Inclusion was self-reported, and the paper does not report inter-tester reliability or whether measurements were repeated on different days. The 10-degree classification threshold was chosen by the authors to avoid measurement interval errors, not from a clinical outcome. The paper reports sex differences but not whether symptoms, activity level, or joint laxity explain them.
The easy way to misread this
Do not read a difference of more than 10 degrees between hip internal and external rotation as a diagnosis or a treatment target. The study was done in healthy young Japanese medical students, and it did not test whether correcting that difference changed pain, function, or injury risk.