Fig. 5

Representative histological images of fracture sites of the diclofenac (a and b), prednisolone (c) and control (d) groups. Each section is oriented with the cortical bone on the bottom, periosteal fracture callus on the top and fracture site in the middle. Magnification 40 × (a, b, d) or 25 × (c). Scale bar: 500 μm. Left diagram: % of samples with the respective tissue within the fracture gap; right diagram: % of samples with bony fracture gap bridging. The diclofenac-treated rats often developed areas of high bone resorption (denoted by arrows) at the CB, the F and the periosteal callus junction. A shows a gap without any signs of a union. Note the lack of CA. B shows a fibrous bone union. In the prednisolone group (c), osteocondral bone union and active new bone formations were detected indicating that endochondral ossification had occurred, although the periosteal OC did not bridge the gap. Generally, calluses contained minor amounts of cartilage, but in half of the samples, residual FCT was still detectetable (left diagram). D shows a sample with OC only and complete union with trabecular structure (right diagram). The normal fatty BM was replaced by bone, the AB seen in D is an artifact of the embedding procedure. Staining: LL (bone: red, cartilage: blue; fibrous connective tissue: pale blue to grey/white). CB = original cortical bone, OC = osseus callus, CA = cartilage, CC = calcified cartilage, WB = woven bone, FCT = fibrous connective tissue, F = fracture site, AB = air bubble, BM = bone marrow, arrow = zone of resorption