Fig. 1: Analysis of the fracture gap after osteotomy in 12-month-old mice revealed a delayed fracture healing process in immunologically experienced (immunoaged) mice.

a Representative images of the newly formed bone (red) and cortical bone (gray) in the fracture gap 21 days post-surgery, which were analyzed via microcomputed X-ray tomography. b Callus volume (TV) was significantly decreased in the immunoaged group, whereas bone volume (BV), bone mineral density (BMD), trabecular number (Tb.N), and trabecular thickness (Tb.Th) were not significantly different between the two groups. The ratio of bone volume to total volume (BV/TV) was not affected by the immunological experience. However, the diminished bone formation in the immunoaged group led to a less stable fracture callus, as shown by a lower minimal polar moment of inertia (MMIp). N = 4 per group; box-and-whisker plot with a line at the median; Welch’s t-test.