Abstract
Background
Despite aggressive debridement, thorough irrigation, administration of systemic antibiotics and staged treatment, many open fractures still become infected. A graft that can promote bone regeneration and prevent infection could decrease complications. Polyurethane (PUR) scaffolds have been previously shown in separate studies to be non-toxic, osteoconductive, can promote bone growth through BMP delivery and prevent infection by having sustained release of an antibiotic. This scaffold can deliver both BMP and vancomycin simultaneously; the purpose of this study is to determine if the co-delivery of the antibiotic inhibits bone formation.
Methods
Using an established critical size defect rat femur model, the amount of bone formation created by PUR scaffolds containing low and high doses of rhBMP-2 (2.4 μg and 22.4 μg respectively) and 0.8 mg vancomycin (8% of graft by weight) were compared to scaffolds that contained rhBMP-2 without antibiotics. After 4 weeks, the femurs were harvested and bone growth was assessed using microCT.
Results
There were no significant differences in bone growth between the groups that had the high dose of rhBMP-2. Surprisingly, the scaffolds that had the low dose of rhBMP-2 and vancomycin promoted more bone formation than scaffolds that had rhBMP-2 and no antibiotics.
Conclusions
The addition and co-delivery of vancomycin to the scaffolds did not inhibit bone growth. The addition of vancomycin to the PUR scaffolds may have altered the release kinetics of the rhBMP-2; this may explain the increase of bone formation in this group. This study demonstrates that incorporation of a therapeutic and a clinically-relevant level of vancomycin does not inhibit bone formation. These results suggest that a dual delivery bone graft has potential to reducing complications associated with open fractures.
