Xenogenic bone with chitosan/norvancomycin sustained-release system for treatment of infectious bone defects in rabbits

Abstract

Objective To investigate the effects of xenogenic bone with chitosan/norvancomycin sustained-release biomaterials in treating infectious bone defects in rabbits. Methods Xenogenic bone with chitosan/norvancomycin sustained-release biomaterials was made by electrospinning technique. Rabbit infectious bone defect models were made by Methicillin-resistant Staphylococcus aureus. A successful model was evaluated with the standard of more than three points in Norden score assessment. All models were divided into two groups by random number table method, with eight models in each. The control group was treated with surgical debridement, and the experimental group was implanted with bone particles of xenogenic bone with chitosan/norvancomycin sustained-release system after debridement. Postoperatively, general conditions, X-ray, histological results of HE staining, and bacteriological examination results of the rabbits were observed. Results X-ray showed significant bone defects, sequestration, periosteal reaction, and soft tissue swelling after one month of modeling, with Norden score of (3.84±0.52)points. The general conditions were good and the sinus tracts were healed in experimental group after two months of treatment. The control group demonstrated generally poor conditions with swollen sinus and purulent discharge. Two rabbits were died of sepsis. The pathological scores of tibial were (0.41±0.08)points in experimental group, and (3.27±0.26)points in control group by gross observation. The pathological score of experimental group was significantly lower than control group(P<0.05). The bone defects were basically repaired in experimental group. The longest diameter of bone defect in experimental group was (0.11±0.02)cm, significantly smaller than (0.48±0.06)cm in control group (P<0.05). There were no obvious signs of osteomyelitis and the bone defects were well repaired in experimental group. Periosteal reaction, soft tissue swelling, a substantial number of bone destruction, and sequestration were observed in control group. The Norden score was (1.32±0.23)points in experimental group, lower than (5.21±0.48)points in control group(P<0.05). HE staining showed a large amount of trabecular bone formation, bone cell formation, and fibrous hyperplasia in experimental group, with no obvious signs of infection. On the other hand, infiltration of inflammatory cells, necrotic tissue, and sequestration were observed in control group. The histological score was(0.61±0.10) points in experimental group, lower than (4.21±0.41) points in control group (P<0.05). The negative rate of bacterial culture in experimental group was 33%, lower than 100% in control group (P<0.05). Conclusion Xenogenic bone with chitosan/norvancomycin sustained-release biomaterials has excellent effect in infection clearance and bone defect reparation in treatment of infectious bone defects in rabbits. Key words: Osteomyelitis; Chitosan; Anti-bacterial agents; Drug delivery systems