Comparison of magnetic resonance imaging (MRI) and histopathology in rabbit models of osteoarthritis and immune arthritis.

Osteoarthritis was surgically induced in mature male Dutch Belted rabbits by sectioning the fibular collateral and sesamoid ligaments and removal of the anterior horn of the lateral meniscus. The site of surgical intervention was detectable by MRI. Histopathologic analysis revealed severe focal cartilage lesions on opposing surfaces of the tibia and femur. Histology of cartilage adjacent to the osteoarthritic lesions appeared normal. In another animal model, arthritis was induced by immunization against ovalbumin followed by intra-articular injection of ovalbumin. MRI of immune arthritic rabbit knees showed accumulation of synovial fluid and cartilage degradation. Histopathology was characterized by vascular necrosis of the synovium and depletion of cartilage proteoglycan. MRI can be used to non-invasively follow the therapeutic effects of drug treatment on synovial inflammation and cartilage degradation in rabbit knees.