Fig. 1. Schematic overview of applied in vivo fracture healing model and experimental workflow.
a Applied surgical procedure introducing a 2 mm standardized osteotomy gap in the left femur of young rats, aged 3 months, showing normal bone healing are compared to aged rats (12 months) that had a minimum litter of three, showing biologically compromised bone healing. b Newly formed bone has different properties in successful healing compared to compromised healing. Successful healing showed higher bone volume ratio and trabecular thickness, while bone volume did not change in comparison to compromised healing after 6 weeks. n = 9–10 individual biological replicates, Mann-Whitney U test19,21,22 Central image: external fixator placed on the left femur, right image: dissected femur, where the region of interest (ROI: 2 mm hematoma + 1 mm proximal and distal to fracture gap) has been removed. All bones were placed in the same orientation for histological analysis, with the femur head (proximal) on the left side and the knee condyle (distal) on the right side of the image. BV - bone volume, TV- total volume, Tb – trabecular. Rat icon obtained from: Flaticon.com, artist: Nhor Phai. c Samples were harvested at day 3, 7 and 14 after osteotomy and subjected to the different downstream analysis, ROI – region of interest.