Quantification of morphometric changes in murine experimental osteoarthritis using image analysis.

The aim of this study was to evaluate a method for the quantification of cartilage erosions and osteophyte sizes in a murine model of osteoarthritis (OA). Mice in which OA was induced in the knee joint by intra-articular injection of bacterial collagenase were used. With an interactive image analysis system, the areas occupied by osteophytes and the areas of erosions of the articular cartilage were measured on histological sections by two independent observers at two time points. Measurements of osteophyte areas and cartilage loss at the tibial plateau showed good reproducibility, whereas measurement of cartilage loss at the femoral condyles was less reproducible. Measurement of three frontal total knee joint sections from the middle part of the joint provided a reliable measure for cartilage damage and osteophyte size in the total joint. A cumulative score was developed, composed of both cartilage loss and osteophyte size, which can be used as a general measure for OA of the knee joint. The presented method of quantitative scoring makes it possible to perform correlation studies and to investigate the effect of therapeutic interventions on the osteoarthritis process.