Cartilage thickness and split-line pattern at the canine humeral trochlea.

Objective: To characterise the humeral trochlea in middle to large breed dogs in respect to split-line pattern and cartilage thickness. Methods: In 15 paired cadaveric elbow joints of mature dogs (>20 kg body weight) collagen network orientation of the hyaline cartilage of the humeral trochlea was visualised using a traditional split-line technique in which a dissecting needle dipped in India ink was inserted into the cartilage (n = 10). Cartilage thickness was measured radiographically on osteochondral plugs harvested at four representative locations within the joint surface of the humeral trochlea (n = 15). Results: The joint surface of the humeral trochlea showed a distinct pattern of centripetally oriented split-lines with less pronounced or even absent split-lines caudo- proximally towards the olecranon fossa. Median cartilage thickness at the canine humeral trochlea was 0.51 mm (interquartile range: 0.42 - 0.61 mm). Centrally, at the region where osteochondrosis lesions commonly occur in middle to large breed dogs, the median cartilage thickness was 0.55 mm (interquartile range: 0.48 - 0.62 mm). Clinical significance: When focusing on anatomical joint resurfacing while performing osteochondral transplantation at the canine humeral trochlea, transplants should be implanted such that their split-lines are oriented centripetally. Hyaline cartilage thickness of transferred grafts should be in the range of half a millimetre to optimally match the situation at the canine humeral trochlea.