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

Abstract

Objective: To determine if medial patellar luxation (MPL) in Yorkshire Terriers is associated with tibial torsion. Study Design: Prospective cross-sectional study. Animals: Yorkshire Terriers (n = 30; 60 tibiae). Methods: 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. Results: 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. Conclusion: 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. © Copyright 2012 by The American College of Veterinary Surgeons.