To develop a protocol for rabbit knee joint ultrasonography (US); to grade ultrasonographically the meniscal injuries of the anterior cruciate ligament transection (ACLT) rabbit model of osteoarthritis (OA); to assess with US the effectiveness of the ACLT; to compare final US with macroscopy for the evaluation of medial and lateral meniscal injuries depending on the age and weight when ACLT is performed.
Twenty-two skeletally mature and adolescent New Zealand white rabbits were housed during the same period at the Institut Claude-Bourgelat, Lyon, France. Surgical ACLT was performed in the left knee of nine adolescent and five adult rabbits. Final US and macroscopic semi-quantitative grading of the meniscal injuries were compared 5 months after ACLT.
A standardised protocol was developed to evaluate the rabbit knee joint. US was performed in both control and ACLT knees. Normal and abnormal meniscal US appearances were described. A semi-quantitative scale to grade US meniscal injuries was created. Macroscopic and US total meniscal scores were significantly positively correlated (P<0.001, r=0.70). US detection of meniscal injuries was 92% sensitive and 87.5% specific compared to macroscopy. Positive and negative predictive values of US were, respectively, 92% and 87.5%. US detection of the ACLT effectiveness was 100% specific and 78.5% sensitive.
A significant relationship was found between ultrasonographic and macroscopic grading of meniscal injuries. US was both specific and sensitive in detecting meniscal lesions. We propose US as a non-invasive, non-expensive, in vivo imaging technique for preclinical studies in the ACLT rabbit OA model.