Fig. 4

Histological findings on axial sections of femoral trochlea by Safranin-O and fast green staining. a,d Healthy articular cartilage on trochlea at 3, 12 weeks were shown in the SG. b In the patellectomy group, the distribution of articular cartilage was changed. The synthesis of cartilage on the bilateral condyle was increased, while decreased in the center of the trochlear groove at 3 weeks. c In the dislocation group, the articular cartilage on the top of the lateral trochlear facets was significantly increased at 3 weeks. e The PG in 12 weeks, besides the flat trochlea, the articular cartilage in the trochlear groove was visible degenerated compared with the SG. f In the dislocation group, the cartilage both on the trochlear center and the lateral facets was worn out, and the lateral condyle is relative convex compared with the other two groups. Cartilage tissue was red-stained, and the trabecular bone was the blue