Ultrasound assessment of sheep stifle joint undergone lipopolysaccharide-induced synovitis

Abstract Synovitis can be induced in animals through the application of bacterial wall lipopolysaccharide and has similar signs to naturally-occurring synovitis. Several studies have been using the sheep species as an experimental model to understand osteoarticular diseases of the femorotibiopatellar (FTP) joint in humans. There are echographic studies on the standardization of normality of the femorotibiopatellar joint in sheep. However, there is a gap in the literature for changes such as acute synovitis. The objective was to serially describe the sonographic aspects of the synovitis process induced by intra-articular infiltration of Escherichia coli (E. coli) lipopolysaccharide in the femorotibiopatellar joint of sheep. Twelve healthy crossbred sheep (Santa Inês x Dorper) were used. Induction of synovitis was performed only in the right FTP joints, which were serially evaluated using ultrasound examination at baseline moment (M0) and 12 (M12), 24 (M24), 48 (M48), 72 (M72), and 120 (M120) hours after lipopolysaccharide infiltration for synovitis induction. Intra-articular application of E. coli lipopolysaccharide resulted in one or more echographic signs of synovitis (increased synovial fluid volume, folding of the synovial membrane, and cellularity in the joint cavity), which were identified early, 12 hours after inoculation, and regressed over the evaluated times (p=0.0001) until disappearing after 120 hours of inoculation.