Platelet‐Rich Fibrin Induces New Bone Formation to Promote Extreme Lateral Interbody Fusion of Spine in Rabbits

Background: Achieving rapid bone fusion is critical for preventing complications in Extreme Lateral Interbody Fusion (XLIF), yet harvesting sufficient autologous bone presents surgical limitations. Platelet-rich fibrin (PRF), an autologous biomaterial rich in osteogenic growth factors, offers potential as a bone graft enhancer. This study evaluated the efficacy of PRF combined with allogeneic bone in promoting interbody fusion using an XLIF-simulated rabbit model. Methods: In vitro, bone marrow mesenchymal stem cells were cultured with PRF, allogeneic bone, or PRF/allogeneic bone composites. Assessments included biocompatibility (CCK-8, Calcein-AM/PI), cell adhesion (phalloidin/DAPI), and osteogenic differentiation (alkaline phosphatase activity/staining, Alizarin Red S). PRF, allogeneic bone, and their composite (PRF/allogeneic bone) were evaluated in a rabbit XLIF model. Autologous iliac crest bone served as a positive control, while empty cages provided negative controls. Endpoints included radiographic (micro-CT), mechanical (biomechanical testing), histological (H&E, methylene blue-acid fuchsin, TRAP), and biochemical (ELISA) evaluation at postoperative 2, 4, 8, and 12 weeks. Results: In vitro experiments demonstrated that PRF/allogeneic bone composites exhibited noncytotoxic properties and osteogenic-promoting effects when combined with titanium alloy cages. In vivo, fusion progressed temporally across all groups, with the PRF/allogeneic bone composite yielding 12-week fusion rates by manual palpation and micro-CT equivalent to autograft. Biomechanical strength and bone mineral density of PRF/allogeneic bone matched autograft, exceeding allogeneic bone. Histology demonstrated accelerated fusion kinetics: early angiogenesis (2 weeks), fibrocartilage formation (4 weeks), and complete trabecular bridging by 12 weeks. ELISA confirmed earlier BMP-2/VEGF peaks (2-4 weeks) versus allogeneic bone. Conclusions: These results indicated that the combination of PRF and allogeneic bone successfully induced intervertebral bone formation in the rabbit XLIF model. PRF can serve as a physiological natural fusion material, inducing osteogenesis and achieving spinal fusion. Its osteopromotive effects, cost-effectiveness, and autologous origin support its potential as a superior graft alternative for XLIF procedures.