Surgically-induced knee joint instability in rats by transection of the Anterior Cruciate Ligament (ACLT), resection of the medial meniscus (tMx) or a combination of both (ACLT and tMx), is one of the most commonly used experimental animal models of osteoarthritis (OA), see [1] and [2].The model is suitable for studying basic pathophysiological aspects of OA and for the pharmaceutical development of disease-modifying drugs.
The severity of joint destruction can best be demonstrated in coronal histological sections of the whole knee joint stained with Toluidine Blue -Safron du Gatinais (or with other combinations of staining (see related APPs: 10026, 10027 and 10061). The most important histopathological hallmarks are surface fibrillation and erosion of the articular cartilage, decrease in chondrocyte number, loss of proteoglycan staining and a sclerosis (thickening) of the subchondral bone plate.
Traditionally, the evaluation of the severity of joint damage is done by subjective semi-quantitative grading of the different histopathological features using defined scoring systems, see [3]. However, even with “blinding’ of the observers and sample randomization, this methodology is prone to bias, suffers from low sensitivity to change and requires considerable experience in histopathology. On the other hand, quantitative digital histomorphometry of cartilage destruction and subchondral bone sclerosis can offer an objective, less time consuming and more sensitive assessment of OA histopathology, see [4].
This APP can be used for quantifying a number of parameters relating to joint damage: cartilage surface length, cartilage surface fibrillation, and solid bone percent.