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 rabb its by sectioning the fibular collateral and sesamoid ligaments and re moval of the anterior horn of the lateral meniscus. The site of surgic al intervention was detectable by MRI. Histopathologic analysis reveal ed severe focal cartilage lesions on opposing surfaces of the tibia an d femur. Histology of cartilage adjacent to the osteoarthritic lesions appeared normal. In another animal model, arthritis was induced by im munization 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 characte rized by vascular necrosis of the synovium and depletion of cartilage proteoglycan. MRI can be used to noninvasively follow the therapeutic effects of drug treatment on synovial inflammation and cartilage degra dation in rabbit knees.