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

Abstract

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. 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. 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. The directional release system described here can improve the process of fracture healing and is a promising technique for repairing femoral neck fracture.