Acompanhamento imaginológico do desenvolvimento esquelético da pelve, fêmur e tíbia associado a métodos de diagnóstico da displasia coxofemoral em gatos

Abstract

The objectives of this study were to monitor radiographically the skeletal development of the hip and stifle joints until the closure of the growth plates and to evaluate the viability of the ultrasonography (US), radiographic distraction method (RDM), conventional radiographic method (CRM) and computed tomography (CT) in the diagnosis of the hip dysplasia (HD) in cats. Radiographic examinations were obtained from the hip and stifle joints of 15 domestic cats at weekly intervals during the first month and biweekly until four months of age, when the tests started to be performed monthly. US and RDM were performed in 17 cats with mean age of 21.4 and 107.83 days, respectively. CRM and CT were performed in 15 cats with a mean age of 559.07 days. In the CT, the lateral center edge angle (LCEA), the center distance index (CD), the dorsal acetabular rim angle (DARA) and the dorsolateral subluxation score (DLS) were measured. The ischiopubic growth plate closed at two months of age, followed by fusion of the iliopubic and ilioischial plates, the proximal femoral epiphysis, the greater trochanter, and the proximal fibular epiphysis. The distal femur and proximal tibial growth plates were the last to close with fusion at 18 months. The closure time of the growth plates were smaller in females. The ossification centers appeared, in time ascending order, beginning with the lesser trochanter and followed by the sequence of greater trochanter, proximal fibular epiphysis, tibial tuberosity, patella, ischiatic tuberosity, lateral fabella, and lateral sesamoid of the popliteus muscle. The mean values of the and angles were respectively 62,41º e 44,94º. The mean distraction index (DI) was 0.13 and the mean value of the Norberg angle (NA) obtained by CRM was 96, 57º. The mean values of LCEA, CD, DARA and DLS were 86º, 0.34, 21.6 and 44.61%, respectively. Positive correlations were found between LCEA and DLS and between DLS and body mass. The NA, LCEA and DLS values were higher in males but females presented higher DARA. DI correlated negatively with NA. It was concluded that the closure of the hip and stifle joints growth plates occurs approximately at 18 months of age and that the imaging tests, each of them in an appropriate age, help in the diagnosis of HD and can guide the clinical conduct.