Anatomical Variations of the Canine Glenoid Cavity and Adjacent Structures Stabilising the Shoulder Joint-An Explorative Study

Passive stabilisers of the canine shoulder joint include the articular surfaces, glenoid labrum, joint capsule and glenohumeral ligaments, in functional entity with the biceps brachii tendon. Their anatomical description differs widely. This explorative study aimed to screen a heterogeneous group of dogs on variations of these structures. Twenty-three canine forelimbs were dissected. The glenoid cavity outlines, their circularity values, and the configuration of the glenoid labrum and ligaments were recorded, as well as their relationship to the biceps brachii tendon. The shape of the glenoid cavity differed between dogs and left/right limb (circularity 0.73-0.83). A protruding, fibrocartilaginous labrum was present caudolaterally in 45% of the limbs. The medial glenohumeral ligament occurred in all dogs, in three shape variants. The lateral ligament was present in few dogs. Between the joint socket and the ligaments or 15% of the biceps brachii tendons was a synovium-lined space. More frequently, the gap between tendon and joint socket was filled with loose connective tissue. There was no clear relation between size, body condition score and muscle mass of the dog and occurrence of variants of the analysed structures. The biomechanical implications of the individual variants still need to be studied.