Significantly increased bone volume in a critical-sized defect model in the rat animal model by transplantation of a stand-alone vascularized periosteal flap

Purpose: The repair of bony non-unions remains challenging and often requires graft material due to limited availability of autologous bone. The aim of this study was to investigate the potency of a stand-alone pedicled periosteal flap (PF) versus a ligated periosteal flap (PFx), an empty defect and a crossover group in terms of newly formed bone in a 5 mm critical-sized defect in the rat femur diaphysis. Methods: The following 4 treatment groups were formed out of a total of 36 male Sprague Dawley rats: Pedicled periosteal flap, ligated periosteal flap, crossover (each n = 10) and empty defect group (n = 6). A prospective randomized plate osteosynthesis was performed. The periosteal flap was dissected along with the supplying vessel from the medial femoral condyle with the aid of magnifying glasses and fixed to the plate and to the defect with a suture. Regular radiographic and µ-CT examinations were performed to determine bone volume inside the defect, as well as descriptive histological examinations. Results: Newly formed bone tissue was measured by Bone Volume / Tissue Volume. The significant highest ratio to the control group was detected in the PF group after 10 weeks (18.77%) compared to the crossover- (11.28%; p = 0.0436), the PFx- (10.98%; p = 0.0411), and the control group (10.47%; p = 0.0293). No relevant differences were found in the descriptive histological examination. Conclusion: According to the observed results, bony healing of non-union defects can be supported with a pedicled periosteal flap. The superiority of the pedicled compared to the ligated periosteal flap suggests that the improved blood flow within the defect area is an essential component of the healing phase itself.