A Study of Femoral Neck Fracture Repair Using a Recombinant Human Bone Morphogenetic Protein-2 Directional Release System

Objective: Significant difficulties are caused by the delayed union of femoral neck fractures. To address this issue, we designed a new device that applies recombinant human bone morphogenetic protein-2 (rhBMP-2) to promote fracture union. Methods: A cannulated screw with holes was used to deliver rhBMP-2 to the fracture site. Fibrin glue was used as an adhesive agent to hold rhBMP-2 in the vicinity of fracture. RhBMP-2 was protected with polylactide-glycolide acid microspheres. RhBMP-2 release was evaluated to determine the effect of the improved screws. Result: When polylactide-glycolide acid microspheres were used, 3.65% of the rhBMP-2 was released in the first 2 h, 5.17% was released within 8 h, and 8.95% was released within 24 h. In the microsphere + fibrin glue group, 1.15% of the rhBMP-2 was released in the first 2 h, 1.75% was released within 8 h, and 6.68% was released within 24 h. Over 42 days, about 76.75% of the rhBMP-2 was released when using fibrin glue, which was lower than the amount released using microspheres alone (91.75%). In dog, a faster repair rate was observed on the side with the improved screw than on the side with traditional screw. Conclusion: The directional release system described here can improve the process of fracture healing and is a promising technique for repairing femoral neck fracture.