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Quantification of Humeroulnar Incongruity in Labrador Retrievers with and without Medial Coronoid Disease

Authors

  • Pavel Proks MVDr, PhD,

    Corresponding author
    • Faculty of Veterinary Medicine, Small Animal Clinic, University of Veterinary and Pharmaceutical Sciences Brno, Brno, Czech Republic
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  • Alois Necas MVDr, PhD,

    1. Faculty of Veterinary Medicine, Small Animal Clinic, University of Veterinary and Pharmaceutical Sciences Brno, Brno, Czech Republic
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  • Ladislav Stehlik MVDr,

    1. Faculty of Veterinary Medicine, Small Animal Clinic, University of Veterinary and Pharmaceutical Sciences Brno, Brno, Czech Republic
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  • Robert Srnec MVDr,

    1. Faculty of Veterinary Medicine, Small Animal Clinic, University of Veterinary and Pharmaceutical Sciences Brno, Brno, Czech Republic
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  • Dominique J. Griffon DVM, MS, PhD, Diplomate ACVS & ECVS

    1. College of Veterinary Medicine, Western University Health Sciences, Pomona, CA
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  • This work was performed in the Small Animal Clinic, University of Veterinary and Pharmaceutical Sciences Brno, Brno, Czech Republic

Corresponding Author

Pavel Proks, MVDr, PhD, Faculty of Veterinary Medicine, Small Animal Clinic, University of Veterinary and Pharmaceutical Sciences Brno, Palackého 1–3, 612 42 Brno, Czech Republic

E-mail: proksp@vfu.cz

Abstract

Objective

To quantify humeroulnar incongruity on elbow radiographs in Labrador Retrievers with or without medial coronoid disease (MCD).

Study Design

Retrospective study of 92 elbows.

Sample Population

Radiographic projections of elbow joints from Labrador Retrievers with MCD (n = 42 elbows; 26 dogs) and without MCD (n = 50 elbows; 25 dogs).

Procedure

The congruity of the humeroulnar joint was measured using an index of subluxation (SI) for each elbow. SI was defined as the distance between the centers of 2 circles drawn along the margins of the incisura trochlearis and the trochlea of humerus on mediolateral digital radiographic projections, normalized by the radius of the circle circumscribing the humeral trochlea. SI was compared between right and left elbows with and without pathology using a Wilcoxon test for paired data, and between normal and abnormal groups with a Wilcoxon test for unpaired data. Mismatch between ulnar curvature and curvature of humeral trochlea and radioulnar incongruency were also noted (Wilcoxon test). The intraobserver repeatability, correlation between SI and radioulnar incongruency, and between SI and mismatch elbow curvature were estimated with a Pearson's correlation coefficient.

Results

Intraobserver repeatability of SI measurement was high (r = 0.97). Mean ± SD humeroulnar incongruity (SI) was greater in elbows with MCD (18.5 ± 6.6) than in the normal elbows (1.7 ± 2.0, P < 0.001). The difference between the diameters of the curvatures of the ulnar and humeral trochlea was greater in elbows with MCD (12.5 ± 4.4) than in the normal group (10.7 ± 4.1, P < 0.05). A moderate correlation was found between the degree of humeroulnar incongruity and a radioulnar step (r = 0.63); however, no correlation was identified between SI and the difference between the diameters of the curvatures of the ulnar and humeral trochleae (r = 0.14).

Conclusion

We propose a radiographic index to measure humeroulnar incongruity on mediolateral digital radiographic projections. This index (SI) supports the presence of humeroulnar incongruity in Labrador Retrievers with MCD. Further evaluation of its reproducibility and clinical importance are warranted. Although there is a moderate correlation between humeroulnar incongruity and radioulnar incongruency, causation has not been established.

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