Relationship between axial radioulnar incongruence with cartilage damage in dogs with medial coronoid disease.

Abstract

OBJECTIVE: To quantify axial radioulnar incongruence (aRUI) in dogs with simple fragmented medial coronoid process (FCP) and those with advanced medial coronoid disease (MCD). STUDY DESIGN: Retrospective clinical study. SAMPLE POPULATION: Group 1: 54 elbow joints (54 dogs) with FCP, but no other visible cartilage damage. Group 2: 32 elbows (32 dogs) with Outerbridge grade 3-4 cartilage pathology of the medial coronoid ± FCP. METHODS: aRUI was quantified using CT based 3D models of the radioulnar joint cup. A sphere was fitted to the trochlear notch of each of the 3D models and aRUI estimated in millimeters based on the relation of the sphere and the radial joint surface. Coronoid disease was diagnosed, classified, and graded using arthroscopy. RESULTS: Mean (±SD) aRUI for group 1 (0.2 ± 0.8 mm) was significantly less than in group 2 (0.8 ± 0.9 mm; P = .001). Overall, 14% had negative aRUI whereas 40% were congruent. Stepwise logistic regression analysis identified age and aRUI, but not body weight as significant covariates. The corresponding odds ratios for advanced MCD were 1.6 for age and 6.4 for RUI, respectively. CONCLUSION: Axial RUI is greater and more prevalent in elbows with severe cartilage disease, and consists most commonly of a short radius.