[Comparative radiologic examination of the canine elbow with and without elbow dysplasia under standardized load]

Application of an X-ray technique under load to determine the humeroradial and humeroulnar joint conformation of dogs with elbow dysplasia (ED). The aim of the study was to determine whether there are significant differences in the measurements of dysplastic joints compared to healthy joints. In addition, we formulated the hypothesis, that a differentiation between humeroulnar and humeroradial incongruence in dysplastic elbows can be made based on the acquired radiographic measurements.

Radiographic measurements were obtained in 149 dogs with ED and compared to the results of a control group established in a previous study. Based on frequently observed measurement variations, these 149 elbow joints were categorized into different subgroups, which we re-compared with the control group. In healthy elbow joints of euthanized dogs, four different radial and ulnar osteotomies were performed with two- and three-dimensional conformation readjustment of the elbow joint. The joints were subjected to the same radiographic measurements and the results were compared to the control and ED groups.

There were no significant differences between the control group and all 149 ED joints. However, a marked delineation was possible because of significant differences and descriptive statistics among the four subgroups of ED joints. One of these subgroups displayed significant differences compared to all the examined groups and was labeled type I (n = 60). Because of a lack of distinction between two subgroups, these were combined and labeled type II (n = 40). Another sub-group comprising all the elbows that could not be classified as either type I or type II was labeled "indiff" (n = 49). The criteria for assigning an affected elbow joint to type I, type II or indiff were three subchondral joint space-widths, three indices calculated from the joint space-widths and one angle.

The technique investigated is suitable to assign a great number of affected joints to an incongruence type (type I or type II).The results of the osteotomy groups provide evidence that the three-dimensional ulnar shortening displays similarities to type I, whereas the three-dimensional radius shortening shows similarities to type II.