Evaluation of antibiotic-loaded calcium phosphate bone cement in an cranium-infected experimental model.

Treatment of calvarial defects has remained a challenge in reconstruction surgery, especially because of infection at these sites. We produced a bactericidal biomaterial for treating infected bone defects by using calcium phosphate bone cement mixed with antibiotics. We evaluated the usefulness of this material mixed with the antibiotic vancomycin in a cranium-infected rat model. The concentration of vancomycin used was 5.0 wt%, as reported in our previous study. In order to establish the rat model, a cranium defect (diameter, 5 mm) was made that was infected with methicillin-resistant Staphylococcus aureus (MRSA). Thirty-six rats were divided into 6 groups depending on whether an autologous graft or bone cement with or without antibiotic was used for the defect. After 1 and 4 weeks, abscess formation was checked, tissue bacterial counts were determined, and pathological examination was performed. At both 1 and 4 weeks, no MRSA was detected on tissue bacterial culture or pathological examination in groups that received bone cement with antibiotics. In groups that received bone cement without antibiotic, MRSA was detected, and the bone cement had compromised and disintegrated into several slices. In conclusion, bone cement that contains antibiotics appears to be effective not only for reconstruction in cases of cranial defect, but also in terms of preventing infection.

Mechanical strength and in vitro antibiotic release profile of antibiotic-loaded calcium phosphate bone cement.

Some case reports described the usage of bone cement mixed with antibiotics. However, there are few studies that referred to experimental research of calcium phosphate cement with antibiotics. Thus, we mixed vancomycin and amikacin with bone cement in various concentrations and examined its characterization and antibacterial activity. As a result, 6.25 wt% over the concentration could not mix with cement. With an increase in the antibiotic content, the hardening time was prolonged and the compressive strength tended to decrease. In consistency, vancomycin mixed cement increased, whereas amikacin mixed cement decreased. The elution of antibiotics showed sustained release. In conclusion, the characteristics of the bone cement changed based on the amount of antibiotics added, and calcium phosphate cement is useful as a drug carrier.