Treatment of posterior interosseous nerve entrapment syndrome with ultrasound-guided hydrodissection: A case report

Figure 3 B-mode ultrasound images of the patient's posterior interosseous nerve. A and B: Affected side (A) and healthy side (B): Transverse axis of the posterior interosseous nerve (PIN) at the inlet of the Frohse arch of the supinator muscle; C and D: Affected side (C) and healthy side (D): Transverse axis of the PIN at the outlet of the supinator muscle; E and F: Affected side (E) and healthy side (F): longitudinal axis of a PIN segment inside the supinator muscle. White arrows: PIN; su: Supinator muscle. The inlet of the right Frohse arch showed tendinous thickening, the PIN was compressed and thinned. There was local adhesion with the surrounding tissues, with unclear demarcation (A), and the left side was normal (B). The right PIN was swollen and thickened at the outlet of the supinator muscle (C), while the left PIN was normal (D). On the longitudinal axis, the right PIN is entrapped, the nerves distal to the entrapment point manifest swelling, thickening, and myelin thickening, with unclear boundaries with the surrounding tissues (E), and the left PIN is normal (F).