Figure 4

Histology of safranin-O-stained sagittal sections of medial and lateral tibia plateau cartilage after 6 weeks and 12 weeks of follow-up. Both in sedentary and in running animals, cartilage of papain-injected joints was severely sulfated-glycosaminoglycan depleted at 6 weeks and 12 weeks. But in running animals, the extracellular matrix showed clear signs of erosion in the medial compartment and even denudation of bone in the lateral compartment.