Ultrasound-guided intervention and assessment of the deep branch of the radial nerve at the tendinous arch of the supinator muscle (arcade of Frohse). Cadaveric validation and in vivo feasibility

Abstract

The deep branch of the radial nerve (DRN) is commonly compressed at the tendinous arch of the supinator muscle (arcade of Frohse), causing pain and motor deficits. Musculoskeletal ultrasound has emerged as a promising tool for nerve evaluation, yet its anatomical validation and interventional safety remain underexplored. This study aimed to validate an ultrasound protocol for DRN assessment and to examine the feasibility and safety of ultrasound-guided approaches at the tendinous arch of the supinator muscle. An observational cross-sectional study was conducted in cadaveric (n=12) and in vivo models (n=10). The study comprised two phases: (1) ultrasound evaluation of the DRN (thickness, depth, cross-sectional area (CSA), echogenicity, branching patterns); (2) assessment of two ultrasound-guided interventional techniques. Ultrasound showed consistent DRN thickness and CSA across groups, with median values of 0.90–1.00 mm and 1.00–1.10 mm2, respectively. In living subjects, depth differed significantly between planes (p = 0.019), with the transverse view yielding greater values (14.05 vs 12.80 mm). Echogenicity analysis classified the DRN as hyperechoic in both planes across all groups. PIN bifurcation was observed in 40% of subjects, while 60% showed a single branch. Both interventional approaches were successfully executed in cadaveric and living subjects, with Power Doppler Imaging confirming no vascular structures along needle trajectories. Ultrasound enables reliable visualization of the DRN at the tendinous arch of the supinator muscle. The standardized assessment protocol and ultrasound-guided interventional techniques were anatomically validated, safe, and feasible. These findings support the clinical application of ultrasound both for diagnostic purposes and percutaneous treatments in DRN alterations at the tendinous arch of the supinator muscle.