Figure 4.

Effect of injurious load on articular cartilage integrity in the synovial joint. Collagen and proteoglycan distribution in an in vivo non-surgical murine model of post-traumatic OA following rupture of the anterior cruciate ligament (ACL) [167]; knee joint integrity was assessed at days 1, 14 and 21 post-rupture and compared to mice with an intact ACL, i.e., unruptured controls. (A–L) show collagen (blue) distributed throughout cartilage and bone. On day 1, collagen is located evenly throughout cartilage (A–D); however, at day 14 post-rupture (F and H), cartilage fibrillation is evident with loss of collagen, followed by complete loss by day 21 (J,L). Proteoglycan distribution (dark blue, (M–X)) shows a similar distribution throughout the cartilage, evenly distributed at day 1 (M–P) but gradual loss as joint damage begins to occur at 14 (R,T) and 21 days (V,X) post-ACL-rupture. Trichrome stain kit (Abcam, ab150686) was used for collagen staining, toluidine blue for proteoglycans. MFC, medial femoral condyle; LFC, lateral femoral condyle; MTP, medial tibial plateau; LTP, lateral tibial plateau; M, meniscus; C, cartilage. Dashed boxes indicate higher magnification medial compartment images directly below. Scale bars: 500 μm.