Quantity and quality of the peroneus longus assessed using ultrasonography in leg with chronic ankle instability.
Shogo Sakai, Yukio Urabe, Masanori Morikawa and 5 others
PMID 30568323WHAT IT FOUND
Muscle size did not differ.
In 9 men with chronic ankle instability, the unstable side had weaker ankle eversion. Ultrasound brightness differed, but the paper gives inconsistent direction.
Key findings
01Evertor strength was lower on the chronic ankle instability side than on the non-instability side.
02Peroneus longus cross-sectional area did not differ significantly between sides.
03Echogenicity was positively correlated with the number of ankle sprains, but the paper gives inconsistent directions for the side-to-side echogenicity difference.
STILL TO COME
How it was doneWhat they foundWhat it means for PTs
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What it does not show
Only nine men with unilateral chronic ankle instability were studied, so the findings may not apply to women, people with bilateral instability, or other age groups. The study compared each person's unstable ankle with their other ankle, not with a healthy uninjured control; the other ankles still had a history of sprains. It was cross-sectional, so it cannot show whether the weakness or fat changes caused the instability or developed after repeated sprains. The paper reports conflicting directions for echogenicity: the table values are higher on the instability side, but the results sentence says the other side was higher. Echogenicity was measured at one point of the peroneus longus, and the paper states there was no correlation between echogenicity and evertor strength.
Declared interests
The authors declared no conflicts of interest.
The easy way to misread this
Do not assume the unstable side definitely has more fat; the paper gives conflicting directions for echogenicity. Also, this small cross-sectional study cannot show that fat infiltration caused weaker eversion or that training the peroneus longus will change either finding.