Risk of Ulnar Nerve Injury Following Caudo-Medial Arthroscopic Portal Creation in the Canine Elbow-A Cadaveric Study

The medial approach is a traditional portal during elbow arthroscopy. Some researchers have suggested that the caudo-medial arthroscopic approach allows better visualization of the medial and caudal elbow compartments. Such a portal is created caudally to the medial humeral epicondyle's caudal aspect in the ulnar nerve's vicinity. Therefore, we investigated the risk of ulnar nerve injury following the caudo-medial portal placement in 30 canine cadavers. After the telescope was inserted, an incision was made to visualize the nerve, and the distance between the cannula and the nerve was measured. An injury was diagnosed when the telescope at least scratched the nerve. The distance between the arthroscopic cannula and the ulnar nerve ranged from 0 to 8.0 mm (median: 0.5 mm) in 60 joints. Nerve injury occurred in 16/30 dogs (53%; CI 95%: 36%, 70%)-in 11 unilaterally and 5 bilaterally. In addition, in eight dogs, the cannula directly touched the nerve, creating a high risk of trauma. In total, nerve injury or high risk of trauma occurred in 21/30 dogs (70%; CI 95%: 52%, 83%). Ulnar nerve injury during caudo-medial arthroscopic portal creation appears common.