Assessment of the Conformation of the Radioulnar Joint Comparing Dogs with and without Medial Coronoid Disease

The aim of our study was to assess the conformation of the radioulnar joint using transverse plane computed tomography in dogs with medial coronoid disease (MCD).The study included 101 elbow joints with arthroscopically confirmed MCD and 20 sound control elbow joints. To assess the conformation of the radioulnar joint, we determined the ratio for the radial head centre of supination and pronation toward the ulnar joint surface in the transverse computed tomography plane. In addition, we assessed the opening angle of the radioulnar joint.The MCD group showed decreased lateral, laterocentral and central radioulnar ratios, with 1.78 (± 0.09) and 1.81 (± 0.07) centrally (<i>p</i> = 0.044), 1.75 (± 0.10) and 1.78 (± 0.09) laterocentrally (<i>p</i> = 0.044) and 1.74 (± 0.09) and 1.77 (± 0.08) laterally (<i>p</i> = 0.044), in the MCD and control groups, respectively, indicating radioulnar joint malformation. The mediocentral and medial sections showed no differences in radioulnar ratios consistent with joint congruity. The opening angle of the radioulnar joint showed no significant differences between the groups.Dogs with MCD showed lateral, centrolateral and central malformation and incongruity of the radioulnar joint in the transverse computed tomography plane. Medial coronoid disease appears to coincide with radioulnar joint malformation ipsilateral to the medial coronoid process and medial joint compartment. Radioulnar malformation in the lateral and central compartments could be a factor in the development of MCD and limit the success rate in arthroscopic MCD treatment.