Using elastography (Aoustic radiation force impulse) to correlate the effects of age, weight, sex, and Norberg angle on the pectineus muscle of dysplastic dogs

Inspired by the possibility of further understanding the role of pectineus muscle in the pathophysiology of hip dysplasia, this study evaluated the correlation between the Norberg angle, weight, sex, and age with the acoustic radiation force impulse (ARFI) elastographic findings of the pectineus muscle in dysplastic dogs through a quantitative analysis using shear wave velocity. Thirty-one dogs that had been radiographically diagnosed with hip dysplasia were selected, with a mean weight of 32.9 ± 8.8kg and age of 4.3 ± 1.5 years. The dogs were submitted to mode B ultrasonography and ARFI elastography of the pectineus muscles, bilaterally. The mean value of the shear wave velocity was 3.5 ± 1.0m/s, which showed a positive correlation with the degree of hip dysplasia (P = 0.0065; r = 0.34) and with age (P = 0.0197; r = 0.30). There was a negative correlation with the Norberg angle (P = 0.0197; r = 0.30), and there was no relation with body weight (P = 0.7435; r = 0.04). It was higher (P = 0.0050) in females (3.9 ± 1.1 m/s) compared to males (3.2 ± 0.8m/s). The variable age contributed to the stiffness of the pectineus muscle in dysplastic dogs. The pectineus muscle was significantly stiffer in females than in males. Weight did not show any association with pectineus muscle stiffness, based on the ARFI elastography findings. The ARFI elastography exam has shown to be feasible in identifying changes in the pectineus muscle of dogs, which could be correlated with the studied variables.