Effect of stifle flexion angle on the repeatability of real-time elastosonography of the patellar ligament in medium to large breed dogs

The objectives of this study were to: describe the elastosonographic findings of the patellar ligament in healthy dogs >15kg in different positions and determine the most appropriate stifle angle to performelastosonography of the patellar ligament.Study design18 clinically healthy dogs, weighing >15kg, were prospectively recruited.B-mode ultrasound and real-time elastosonography of both patellar ligament was performed on days 0 and 14. Elastosonography examinations were performed with the stifle in four positions: standing position; lateral recumbency with the stifle positioned at 135 degreesextension; in full passive flexion and extension. ResultsThe percentage hardness of the patellar ligament was statistically significantly lower when the elastogonographic examination was performed with the dog standing, compared the other positions(P<0.005). The variability in the elastosonography readings for each stifle position, was lowest when the dog was standing (89.32%).Conclusions Elastosonography is a feasible technique for evaluating the elasticity ofthe normal canine patellar ligament in dogs >15kg and would be a useful technique for investigating the mechanical changes within the patellarligament following stifle surgery. Elastosonography of the patellar ligament should be performed with the dog standing to provide the mostaccurate elastosonograms with lowest variability between readings.