Treatment of segmentary bone defects in rabbit tibiae with vascular endothelial growth factor (VEGF)) enhanced hydroxyapatite/gelatin matrix

In the field of orthopedic surgery, bone grafting is usually administered in the treatment of bone defects which occur as a consequence of various conditions. The recent developments in tissue engineering have rendered the utilization of synthetic graft materials with osteoconductive properties possible. These synthetic graft materials may also serve as scaffolds with which other factors promoting bone healing may be used in conjunction. One of these factors is Vascular Endothelial Growth Factor that plays an important role in bone healing by regulating the angiogenesis. The aim of this study was to investigate the effectiveness of local VEGF administration with hydroxyapatite containing gelatin scaffold as the synthetic graft material in the treatment of critical-sized bone defects. For this purpose, an experimental non-union model was established by creating 10 mm. bone defects in the proximal tibiae of 30 skeletally mature New Zealand white rabbits. Following tibial intramedullary fixation, the rabbits were grouped into three: The defects were left empty in the first (control) group, the defects were grafted with synthetic scaffolds in the second group and synthetic scaffolds loaded with VEGF were administered at bone defects in the third group. 5 rabbits in each group were sacrificed on 6th and 12th weeks and new bone growth was assessed radiologically and histologically, well as with bone mineral density measurements (DEXA). On the 6th week, significant differences between each group in all three evaluation criteria were noted. VEGF administered group had significantly better scores compared with the other two groups. The second group also had significantly better scores than the control group. On the 12th week, while no significant difference was noted between the second and third groups, these two groups both had significantly better scores in all three criteria compared with the control group. No signs of solid bony development was observed in the control group. In conclusion, the local administration of VEGF with hydroxyapatite containing gelatin scaffold as the synthetic graft material was effective in the treatment of critical-sized bone defects in this experimental model.