Nerve palpation to reduce the risk of ulnar nerve injury associated with caudo-medial arthroscopic portal creation in the canine elbow – a cadaveric study

The medial portal is the most common type of optical portal used in canine elbow arthroscopy. The caudo-medial arthroscopic portal can be used to improve visualization of humeral condylar lesions and medial coronoid process pathologies, as well as for more accurate identification of the humeral intercondylar fissure. However, due to the proximity of the nerve, caution must be exercised when creating this portal. This study investigated whether the risk of ulnar nerve injury associated with caudo-medial arthroscopic portal placement in canine cadavers could be reduced by palpating the ulnar nerve before creating the portal for the arthroscope, as is done in human elbow arthroscopy. Twenty-six canine cadavers were enrolled in the study: 15 males and 11 females, weighing between 12 and 41 kg. In the 26 dogs (52 elbows) in which ulnar nerve palpation was performed, the distance between the nerve and the arthroscopic sheath ranged from 0 to 10.8 mm. Overall, ulnar nerve injury was observed in 4 / 26 dogs (15%, CI 95%: 6%, 34%): in the left elbow of one dog and in the right elbows of three dogs. Comparison with previous studies indicated that implementing palpation of the ulnar nerve before creating the portal for the arthroscope reduced the risk of ulnar nerve injury threefold, from approximately 50% to approximately 15%. Conclusions: Following palpation and identification, the incidence of ulnar nerve injury is low.