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Evaluation of Tibial Torsion in Yorkshire Terriers with and without Medial Patellar Luxation


  • Funded in part by the Dean's Fund for Clinical Excellence, Department of Clinical Sciences, Cornell University.

  • Presented in part at the Annual ACVS Symposium, Seattle WA, October 19–23, 2010.

Corresponding Author

Ursula Krotscheck, DVM, Diplomate ACVS, DCS Box 25, Department of Clinical Sciences, Cornell University, Ithaca, NY 14853




To determine if medial patellar luxation (MPL) in Yorkshire Terriers is associated with tibial torsion.

Study Design

Prospective cross-sectional study.


Yorkshire Terriers (n = 30; 60 tibiae).


Each MPL was graded using a categorical grading scheme. Computed tomography of the tibiae was performed and tibial torsion angle (TTA) was assessed. MPL grade was analyzed with a general linear model where the independent variables include sex, neutering status, age, weight, and TTA.


Factors that had collective impact on MPL grade were TTA, age, and weight squared. As MPL grade increased, TTA decreased by 0.05° and age increased by 0.13 years. As weight increased, MPL decreased. There was no effect (P > .05) from scorers, side, and neutering status.


Body weight squared, TTA, and age affect MPL grade, suggesting that a torsional deformity may contribute to the development of MPL in Yorkshire terriers along with weight and age.