A Cadaveric Study of Ulnar Nerve Movement and Strain Around the Elbow Joint

There is a lack of data on how ulnar nerve strain varies according to the location around the elbow joint. Therefore, we measured the longitudinal movement of the ulnar nerve around the elbow joint. Four fresh-frozen cadaveric upper extremities were used. A linear displacement sensor was attached to the ulnar nerve at eight measurement points at 20-mm intervals. At each point, the longitudinal movement of the ulnar nerve was measured during elbow flexion. We calculated the strain on the ulnar nerve based on the change in movement between neighboring points. Ulnar nerve movement with elbow flexion had a maximum value (mean, 10.5 mm; p < 0.001) at 2 cm proximal to the medial epicondyle. In the site distal to the medial epicondyle, the movement was small and demonstrated no significant difference between points (p = 0.1). The change in strain between mild flexion (0–60°) and deep flexion (60–120°) significantly differed at 2–4 cm and 6–8 cm proximal to the medial epicondyle (15% versus 3%, p < 0.01; 5% versus 9%, p < 0.05, respectively). The longitudinal movement of the ulnar nerve during elbow flexion occurred mainly at the site proximal to the medial epicondyle and became smaller away from the medial epicondyle.