Intraosseous concentration and inhibitory effect of different intravenous cefazolin doses used in preoperative prophylaxis of total knee arthroplasty

Background

The aim of this study was to compare the intraosseous concentrations and the inhibitory effects on the growth of Staphylococcus aureus of 1 g versus 2 g of intravenous (IV) prophylactic cefazolin in total knee arthroplasty (TKA).

Materials and methods

Eighteen patients (21 knees) with primary knee osteoarthritis were divided into two groups receiving 1 g (12 patients: 14 knees) versus 2 g (six patients: seven knees) IV prophylactic cefazolin prior to the incision in TKA. Subchondral bone samples (proximal tibia, distal femur) were taken during the operation. These samples were analyzed for intraosseous concentration of cefazolin and their inhibitory effects on the growth of S. aureus, using high-performance liquid chromatography (HPLC) and agar disc diffusion bioassays.

Results

The mean intraosseous concentration in the 2 g dose group was significantly higher than in the 1 g dose group in the proximal tibia (p = 0.007) and distal femur (p = 0.016). There were no significant differences between the two groups in terms of mean inhibitory effects in the proximal tibia or distal femur (p > 0.05). No significant correlations were found between the intraosseous concentrations and inhibitory effects in the proximal tibia (r = 0.18, p = 0.52) and distal femur (r = −0.29, p = 0.30).

Conclusion

IV cefazolin at a dose of 2 g produced greater intraosseous concentrations overall than a dose of 1 g. However, the higher intraosseous concentrations did not correlate with higher inhibitory effects.

Level of evidence

Level III.