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Cubital tunnel syndrome is the second most common nerve entrapment neuropathy. When non-operative treatments fail, surgical intervention is indicated. Although there remains no consensus between simple decompression and anterior transposition, there is a growing recognition of improved clinical outcomes in the latter. Few details of ulnar nerve branches around the elbow are available however and their sacrifice may be necessary to facilitate anterior transposition. Therefore, ten cadaveric upper extremities were dissected to delineate the course and branching pattern of the ulnar nerve around the elbow joint; anterior transposition was also performed in the cadaveric specimens. Digital photographs of the dissection study were analyzed using the Image J package. Results show that distal ulnar nerve branches are distributed more laterally towards the olecranon and may potentially restrict transposition more than has been recognized; proximal branches may also overlap incision lines of such transposition procedures.

Background: This study aimed to investigate whether the distance between the radial nerve and rotational center of the elbow joint when observing from the lateral surface of the humerus changes according to passive elbow joint flexion for safe external fixation with a hinged fixator of the elbow joint.

Methods: Twenty fresh-frozen cadaveric arms were dissected. The points where the radial nerve crosses over the posterior aspect of the humerus, crosses through the lateral center, and crosses over the anterior aspect of the humerus were defined in the lateral view of the elbow joint, using fluoroscopy, as R1, R2, and R3, respectively. The distances between the rotational center and each point on the radial nerve were measured when the flexion angle of the elbow joint was 10°, 50°, 90°, and 130°.

Results: The distances between the rotational center and R1, R2, and R3 were 118 mm, 94 mm, and 65 mm, respectively, when the flexion angle was 10°; 112 mm, 93 mm, and 74 mm, respectively, for 50°; 108 mm, 93 mm, and 77 mm, respectively, for 90°; and 103 mm, 94 mm, and 83 mm, respectively, for 130°. The distance between the rotational center and R2 was constant regardless of the flexion angle. With elbow joint extension, the distances between R1 and R3 increased; the safe zone, a region where the radial nerve would not be located on the humerus, was the smallest in extension. When the elbow joint was flexed, the distances between R1 and R3 decreased; the safe zone was the largest in flexion.

Conclusions: This study showed that the radial nerve location on the humerus varied based on the flexion angle of the elbow joint; the safe zone may change. A half-pin can be likely inserted safely, avoiding the elbow joint extension position.