In vivo MRI assessment of knee cartilage in the medial meniscal tear model of osteoarthritis in rats.

We present a new approach for quantifying the degradation of knee cartilage in the medial meniscal tear (MMT) model of osteoarthritis in the rat. A statistical strategy was used to guide the selection of a region of interest (ROI) from the images obtained from a pilot study. We hypothesize that this strategy can be used to localize a region of cartilage most vulnerable to MMT-induced damage. In order to test this hypothesis, a longitudinal study was conducted in which knee cartilage thickness in a pre-selected ROI was monitored for three weeks and comparisons were made between MMT and control rats. We observed a significant decrease in cartilage thickness in MMT rats and a significant increase in cartilage thickness in sham-operated rats as early as one week post surgery when compared to pre-surgery measurements.