State-of-the-Art Patient-Customized Bone Graft Harvesting Strategies

Treatment of critical-size bone defects has been enhanced by advancements in scaffold-guided bone regeneration (SGBR), for which the usage of osteogenic bone graft material is crucial. To optimize the extraction of bone graft, the aspirator + reaming-aspiration (ARA) concept has recently been evaluated in a preclinical in-vivo study as an alternative intramedullary harvesting strategy to the well-known Reamer-Irrigator-Aspirator 2 system (RIA 2 system). As part of the in-vivo study, bone graft obtained from sheep was applied together with a 3D-printed bioresorbable scaffold construct in an ectopic rat model. Fluorochrome labelling with calcein green (day 8), alizarin complexone (day 22) and xylenol orange (day 36) was performed at different timepoints post-surgically. After 8 weeks, probes from five experimental groups were explanted resulting in a total of 58 resin probes for further analysis. Fluorescence of 198 samples was assessed semi-quantitatively through applying a three-stage evaluation scale (“none”, “minimal”, “intense”) by two assessors (LPW and ACB) independently. No fluorescence was defined as the absence fluorescent clusters over the entire sample section after manual screening at 20× magnification. Minimal fluorescence was defined as the presence of a maximum of three fluorescent clusters at independent image sections at 20× magnification. Intense fluorescence was defined as a minimum of three fluorescent clusters at independent image sections at 20× magnification. Preliminary descriptive statistical results are shown in Figure 1. All group 1 “Sc-samples” and 58% of group 3 “ScA samples” show no fluorescence. Minimal fluorescence was observed for 5% of group 2 “ScRIA2 samples”, 32% of group 3 “ScA samples”, 14% of group 4 “ScRa samples” samples, and 41% of group 5 “ScARA samples”. Intense fluorescence was observed for 95% of group 2 “ScRIA2 samples” samples, 10% of group 3 “ScA samples”, 86% of group 4 “ScRA samples” and 53% of group 5 “ScARA samples”. In conclusion, our preliminary data indicate comparable active bone regeneration and bone formation of bone graft material harvested with the new ARA concept compared to the RIA 2 system. In a next step, quantification of the fluorescent sample surface will be performed. Furthermore, advanced statistical analysis and putting the results in relation with histological and immunohistochemical analysis of paraffin samples are required. For any figures or tables, please contact the authors directly.