Fig. 9
Panel a: Toluidine blue stained histology ground sections of one animal per group. The tissue around the test and reference implants has similar aspect both at the cis and trans-cortex. The fracture gap, still evident in all samples, is filled with disorganized calcified tissue. Overall, no significant differences were found between groups. Qualitatively we report more callus in the endosteal area in variable fixation groups. A lower percentage of old bone has been measured in variable fixation groups (VFLS6 – 26.86%; VFLS3 – 28.44%) compared to standard fixation (LS - 30.28%), together with slightly more new bone tissue in variable fixation groups (VFLS3 – 34.62%; VFLS6 – 34.02%) compared to standard fixation (LS - 30.61%). Panel b: Micro radiographs of the sample displayed above corroborating the observation and structure of the calcified tissue. The appearance of the cortices is very similar among groups and shows their activation is not causing a disruption of the cortical pattern. Panel c: Fluorescence overlay images the same samples. Calcein green showed an almost equal deposition of new tissue 3 weeks into treatment, with a higher deposition rate at the trans-cortex in all groups. Highest scores for the intramedullary area were given for VFLS6 followed by LS and VFLS3. At 6 weeks xylenol orange showed slightly more deposition intramedullary and at the cis-cortex in variable fixation groups and comparable deposition at the trans-cortex. Nine weeks post-surgery, VFLS6 showed similar deposition of oxytetracycline gold at the cortices and intramedullary, while the LS group featured more intramedullary deposition than at the cortices and VFLS3 featured more deposition at the cortices and less intramedullary