The arcade of Frohse,
also known as the supinator arch,
is formed by a fibrous band between the two heads of the supinator muscle and it is the most common site of compression of the posterior interosseous nerve (PIN) ( Fig 1 ). The goals of our study were: - to accurately assess the diameter of the posterior interosseous nerve through the arcade of Frohse - to demonstrate the existence of a physiological difference in size during its passage through the upstream,
entry and downstream point...
Methods and Materials
Prospective monocentric study from March to June 2017. Thirty volunteers were included in the study: 15 women and 15 men (range 20-45 years old). Exclusion criteria were: elbow surgery,
muscle weakness. We used 18 MHz linear array transducer (Samsung RS80A).
Volunteers were positioned with elbow extended in supination and the PIN was identified in the long axis at the elbow fold ( fig 2 ). We measured the anteroposterior (AP) diameter of the PIN at the entry point of the...
Mean AP diameter of the PIN was 0.833 mm ± 0.208 upstream the arcade,
0.6 mm ± 0.173 at the level of the arcade and 0.486 mm ± 0.131 downstream.
T-test showed significant PIN diameter difference between the 3 segments (fig2).
The biggest difference was between upstream and downstream with a mean difference of 0.357 mm (-39% p <0.001).
Difference was smaller but still significant between the upstream and the arcade 0.233 mm (-27%,
p <0.001) and between the arcade and the downstream 0.114 mm...
PIN neuropathy is an uncommon peripheral neuropathy.
Our study showed,
in healthy volunteers,
a statistically significant drop of PIN’s diameter during its passage through the arcade of Frohse not to be wrongly considered as a nerve entrapment. The goal in the future is to compare these results with those in people presenting signs of PIN neuropathy in order to find a cut-off value (fig3). Other sites of PIN compression in the elbow area have been described such as the medial head of the...
A Few References: Dietz AR,
Nerve ultrasound identifies abnormalities in the posterior interosseous nerve in patients with proximal radial neuropathies: Nerve Ultrasound in Radial and PIN Lesions.
mars 2016;53(3):379‑83. Djurdjevic T,
High resolution ultrasound in posterior interosseous nerve syndrome: Ultrasound in PIN Syndrome.
janv 2014;49(1):35‑9. Prasartritha T,...
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