Ultrasound Shear Wave Elastography of Ulnar Nerve and Flexor Carpi Ulnaris in Young Adults: A Preliminary Observation.

OBJECTIVES: To assess biomechanical properties of the ulnar nerve and flexor carpi ulnaris (FCU) muscle in young healthy adults using ultrasound shear wave elastography (SWE). METHODS: Using an elbow brace to standardize 30° and 90° of elbow flexion, shear wave velocity (SWV, m/s) of the ulnar nerve in cubital canal and FCU were measured using 18-MHz linear array transducer. The difference in SWV of ulnar nerve and FCU between both sides, between 30° and 90° elbow flexion, and between non-compression and compression conditions were analyzed using paired t-tests. Inter- and intra-observer reliability was analyzed using intraclass correlation coefficients (ICC) and Bland-Altman analysis. RESULTS: The study included 12 men and 12 women (mean age 26 ± 2 years) who had no upper extremity pathologies. No significant differences in nerve SWV were observed between male and female participants or between left and right sides (p > .05). Ulnar nerve SWV increased significantly under compression at 30° and 90° elbow flexion (p < .001) compared to non-compression. SWV of FCU also increased with muscle contraction at 30° and 90° elbow flexion compared to muscle relaxation (p < .001). A moderate and positive correlation in SWV between ulnar nerve and FCU was observed at variable elbow angles and stress conditions (Spearman r = 0.64, p < .001). Intra- and inter-observer reliability for performing SWE was moderate to good (ICC >0.79). CONCLUSIONS: SWE is a feasible method for quantifying biomechanical properties of the ulnar nerve and FCU in young healthy adults under physiological conditions, demonstrating good inter- and intra-observer reliability and minimal measurement variability.