Assessment of Elbow Joint Incongruity as a Primary Cause of Canine Elbow Dysplasia: Comparative Imaging Analysis...

Incongruity is a primary cause of elbow dysplasia. The aims of this study included assessing the prevalence of incongruity, determining reference ranges for joint space widths of the elbow joints in asymptomatic animals, and analyzing the correlations between incongruity and other primary causes of elbow dysplasia.

The study was conducted in 108 dogs of different sexes and aged from 3 to 15 months. The animals were divided into two groups: group I (50 dogs) comprising healthy animals and group II (58 dogs) comprising sick animals.

All the dogs in group I were considered healthy. In these dogs, the mean radioulnar "step" height based on the X-ray examination was 0.85 ± 0.33 mm, the mean joint space width of the humeroulnar joint assessed in the computed tomography (CT) examination was 1.34 ± 0.34 mm, and the mean joint space width of the humeroradial joint was 1.43 ± 0.31 mm. In group II, incongruity was detected in 30 and 41 dogs based on the X-ray and CT scan images, respectively. The mean radioulnar "step" height in the dogs with incongruity based on the X-ray examination was 2.05 ± 0.53 mm, while that in the CT examination was 2.33 ± 0.74 mm. The mean joint space width of the humeroulnar joint based on the computed tomography (CT) examination was 3.189 ± 1.03 mm, and the mean joint space width of the humeroradial joint was 2.916 ± 0.702 mm. The most common diagnosis was a combination of incongruity with medial coronoid process disease.

Based on the conducted studies, the following reference values were determined: for the height of the radioulnar "step" measured on radiographs, 0.3-1.5 mm; for the height of the radioulnar "step" measured in the CT examination, 0-1.5 mm; for the width of the joint space of the humeroulnar joint measured on MPR images in the sagittal section, 0.8-2.2 mm; and, for the width of the joint space of the humeroradial joint measured on MPR images in the sagittal section, 0.7-2.5 mm. An elbow incongruity was the most frequently diagnosed primary cause of elbow dysplasia, most often occurring in combination with other causes, particularly medial coronoid process disease.