Experimental Study Of Nonvascularized Fibular Flap For Repairing Mandibular Defects And Fibular Regeneration In Mini-pigs

Objectives:This study is to explore the mechanism of non-vascularized fibular flap transplantation to reconstruct the growth of the mandibular defect and the regeneration of the fibular in the donor area,to provide a clinical theoretical basis for the repair of the mandibular defect with the non-vascularized fibular flap.Methods:Five 3-month-old Diannan miniature pigs were used to repair the 5.0-6.0cm defect of the mandible of the animal using non-vascularized fibular flaps.The DICOM data of the pre-and post-operation were imported into SimPlant Pro11.04 for three-dimensional reconstruction and analysis.Dolphin Imaging11.8 was used to reconstruct the X-ray film on the day after the operation and the 6 months after the operation,and then HE staining and Masson trichrome staining were used to observe the growth of non-vascularized fibula flap and the regeneration of fibula in the donor area.Results:CT scan showed that there was a connection between fibular and mandible in the transplanted area one month after the operation,and new bone formation began to be reconstructed at the end of the fibula in the donor area.A complete continuous bone connection was formed,and the reconstruction was basically completed.Among them the fibula on the right side of the animal was partially absorbed,one was severely absorbed on the right,and one was infected on the left.The fibula transplanted after 30 minutes separation was basically connected to the mandible at the 6th month after the operation.In the periosteal group,the fibula on both sides of the donor site grew to the middle,but a complete and continuous cortical bone was not formed.HE staining showed that a large number of bone islands and trabecular bone structures appeared at the boundary between the fibula and mandible in the transplanted area and more bone is islands and trabecular bone structures were be observed in the regenerating fibula in the donor area.Masson trichromatic staining showed that a large number of blue-stained mineralized areas and new red-stained osteoid tissue at the junction of the transplanted fibula and mandible.At 6 months the regenerated fibula showed a deeper red stain osteoid bone tissue.Conclusion:Periosteum plays an important role in bone repair and regeneration.Therefore,preserving the integrity of the periosteum around the fibula during surgery is crucial for fibula regeneration.Nonvascularized fibular flap is a feasible method for repairing partial defects of mandible.