Morphological changes in the interosseous membrane of the forearm during forearm rotation.
Tomoki Ono, Koji Iwamoto, Masahiko Monma and 2 others
PMID 39493683WHAT IT FOUND
In 17 healthy forearms imaged with the arm raised, the membrane between radius and ulna changed shape with rotation: it bowed toward the palm in middle and supinated positions, and toward the back of the forearm in pronation.
Key findings
01In the middle forearm position, the membrane was palmar convex with a negative angle of 159.6°.
02In supination, the membrane was palmar convex with a negative angle of 141.6°.
03In pronation, the membrane was dorsal convex with a positive angle of 141.7°.
STILL TO COME
How it was doneWhat they foundWhat it means for PTs
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What it does not show
The study included 17 healthy right forearms, with an average age of 31.0 years, so it does not show what happens in children, older adults, or painful or surgical forearms. The scans were taken with the limb held still in set positions, not during an actual overhead sport motion. The elevated arm position may have made supination smaller than pronation, and the middle position was defined relative to space, not the humerus. Only one observer analysed the images, and no patient outcomes or treatments were tested.
Declared interests
The study received no specific funding, and the authors declared no conflicts of interest.
The easy way to misread this
Do not conclude that the membrane causes instability or that a therapy can be targeted to it. This study only measured shape in 17 healthy forearms held still in three positions.