Fig. 3

Representative histological images of fusion masses. Hematoxylin-eosin (a, c, e) and Masson’s trichrome (b, d, f) staining (× 2.5, × 10, and × 20 magnification, respectively) of representative fusion areas (yellow dashed lines) from autograft hip (a, b), allograft hip (c, d), and allograft femur (e, f) groups. Unlike the allograft femur group (e, f), fusion masses arising from hip-derived grafts (a, b, c, d) exhibited bone formation on both adjacent transverse processes (stars). Within the intertransverse space in hip-derived graft groups (a, b, c, d), bridging osteoid (*) with a high number of osteoblasts on the surface (black arrows) and abundant osteocytes within lacunae (black arrowheads), as well as incipient bone marrow (+) in the center of the fusion masses were observed. Black bar in all images represents 1 mm