The aim of this study was to evaluate the stifle joint of 18 healthy Santa Ines sheep in different age groups, utilizing both radiographic and ultrasonographic exams. The animals were divided into 3 equal groups: Group I, 6-8 months old (mean weight of 25 kg); Group II, 2 years old (mean weight of 50 kg); Group III, 3-5 years old (mean weight of 55 kg). Radiographically the lateral femoral condyle was larger than medial femoral condyle, and the lateral tibial condyle was larger than the medial tibial condyle in the craniocaudal view. The patella showed a pyramidal base and a pointed apex in mediolateral view. The medial sesamoid bone of the gastrocnemius muscle was observed in one, and the lateral sesamoid bone was observed in four of 36 hindlimbs evaluated. Out of all the radiographs, the fibula was identified in only one animal - a Group III sheep. The distal femoral, proximal tibial and tibial tuberosity physes could be evaluated in all radiographs. These physes were closed or semiclosed in all animals of Group III. According to ultrasonographic examination, the convex surface of the patella was observed as a hyperechogenic line with an acoustic shadow and the articular cartilage of the femoral condyles was observed as a hypoechogenic line outlining the bone surface. The intermediate patellar ligament presented as a fibrilar hyperechogenic structure measuring 1.2-3.2mm in thickness. The lateral and medial menisci appeared triangular in shape, slightly heterogeneous, and moderately echogenic. In conclusion, the radiographic images were useful to evaluate the bone structures of the stifle, and physis closure and the ultrasonographic images allowed to identify soft tissue structures, such as menisci and patellar ligament.
Joint; stifle; imaging methods; sheep
