Ultrasound validation of surface localization for the recurrent motor branch of the median nerve: a cadaveric study

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BACKGROUND: Rapid identification of the recurrent motor branch (RMB) of the median nerve (MN) via ultrasound is relatively challenging, and its timely accurate localisation facilitates early assessment. This study established a surface landmark-based coordinate system for RMB localisation and verified its effectiveness through cadaver dissection and high-resolution ultrasound (HRUS). MATERIALS AND METHODS: Fifty embalmed wrist specimens were dissected to record RMB anatomical variations. A coordinate system was constructed with the distal wrist crease as the X-axis and the radial border of the ring finger as the Y-axis. Key RMB coordinate points were collected to define a target zone. High-resolution ultrasound evaluated the RMB detection rate within this zone in 20 volunteers, and 4 frozen wrist specimens were dissected to verify HRUS localisation accuracy. RESULTS: The RMB was predominantly single-branched (76%), with 74% running extra-ligamentously, 72% penetrating the palmar aponeurosis fibrous layer, and 67% passing through the tendinous fibrous bundle of the flexor pollicis brevis (FPB) muscle. Key anatomical points of the RMB were concentrated at 11.34 mm from the X-axis (defined as the distal wrist crease) and 36.12 mm from the Y-axis (defined as the radial border of the ring finger). The volunteer detection rate was 73%, with 88% of HRUS-identifiable RMBs localised within the zone. Frozen specimen dissection confirmed 100% HRUS accuracy. CONCLUSIONS: This coordinate system effectively predicts RMB distribution. Preoperative combination with HRUS facilitates rapid RMB identification and evaluation, potentially enhancing surgical safety.

Ce résumé expose les affirmations des auteurs. BNTIC ne l’interprète pas comme une validation indépendante des résultats.