Anatomical and safety considerations in establishing portals used for canine elbow arthroscopy

Objectives: To describe the relationship of the major muscular, ligamentous and neurovascular structures in relation to standard medial elbow arthroscopic portals used in dogs, and to evaluate their potential iatrogenic lesions. Design:Anatomical study using 20 canine cadaveric elbows. Methods: Arthroscopic explorations were performed using medial portals. Three 4 mm orthopaedic pins were introduced in place of the arthroscope, egress canula and instrumental portals. Limbs were dissected. Distances between pins and neurovascular structures were measured. Muscle, ligament and cartilage lesions were recorded. Results: Minimal muscular lesions were observed. No ligament injury was evidenced. Superficial iatrogenic cartilage lesions were observed in three joints. The arthroscopic portal was 23.1 mm (range: 16 to 28.5 mm) caudal to the brachial artery, 21.0 mm (13-30.5 mm) caudal to the median nerve, and 4.0 mm (1-7 mm) cranial to the ulnar nerve. The instrumental portal was 16.3(9-24 mm) caudal to the brachial artery, 13.5 mm (7-24.5 mm) caudal to the median nerve, and 11.8 (8-18 mm) cranial to the ulnar nerve. The egress portal was 21.4 mm (12-37 mm) caudal to the ulnar nerve. Conclusions and clinical relevance: The study confirmed the safety of elbow medial arthroscopic portals. Care must be taken when placing the camera portal so as to avoid injury of the ulnar nerve. Should extensive intra-articular procedures be needed, manipulation of instruments should be done cautiously in the cranio-medial compartment of the joint due to the proximity of the median nerve to the capsule.