Effect of anatomic variation in caudal tibial plateau on the tibial plateau angle in dogs: a cadaveric study.

Objectives: To determine the effect of using two different landmarks to identify the caudal point on the joint orientation line in the sagittal plane in tibial plateau angle measurement in dogs: the caudal margin of the medial condyle as the anatomic tibial plateau angle and the tibial insertion of the caudal cruciate ligament as the conventional tibial plateau angle. Methods: A total of 170 tibiae from 85 mid- and large-breed dogs were used. The two joint orientation lines were drawn on photographic images of the bones. The angles between the line perpendicular to the tibial axis and the two lines were then measured as the anatomic and conventional tibial plateau angle. Results: The mean conventional tibial plateau angle (25.2+/- 2.60 degrees) and anatomic tibial plateau angle (23.5 +/- 2.59 degrees) differed significantly (P<0.001), and the degree of this difference varied significantly among seven breeds (P<0.01). Clinical Significance: The results of this study suggest that the locations of the caudal margin of the medial condyle and the tibial insertion of the caudal cruciate ligament differed, leading to inconsistent identification of the joint orientation line depending on the landmark used.