Objectives The purpose of this study was to objectively estimate humeroradial (HR), humeroulnar (HU) and radioulnar (RU) congruity on mediolateral elbow radiographs of Labrador and Golden Retrievers without and with medial coronoid disease (MCD), and to determine the correlation between traditional and modified RU-step assessment techniques.
Materials and Methods Extended mediolateral elbow radiographs of Labrador and Golden Retrievers without MCD (control group) and with confirmed MCD (diseased group) were investigated. Absolute and average HR and HU distances were determined and standardized by the radius of the corresponding humeral condyle. Traditional RU-step was measured, and a modified procedure of RU-step assessment was generated. The correlation between the two RU-step assessment procedures was tested.
Results A total of 131 (197 elbows) Labrador and Golden Retrievers met the criteria for inclusion in the control and diseased groups. The normalized HR and HU distances increased significantly (p ≤ 0.002) in dogs with MCD. There was a significant increase (p < 0.0001) in the traditional and modified RU-step in dogs with MCD. A significant correlation (r s = 0.74, p < 0.0001) was identified between traditional and modified RU-step calculated for control and diseased elbows.
Clinical Relevance Dogs with confirmed MCD had quantitative radiographic evidences of elbow incongruity. Modified RU-step procedure may be an alternative to the traditional technique and can be utilized during routine quantification of HR and HU congruity. Validation of the reported measurements is, however, warranted.