Bone and serum concentrations of five cephalosporin drugs. Relevance to prophylaxis and treatment in orthopedic surgery.

Bone and serum concentrations of five cephalosporins were assayed in 92 patients undergoing elective hip or knee prosthetic joint arthroplasty. One hundred twenty-five bone samples were assayed. Although there was no direct relation between serum and bone antibiotic concentrations, a trend toward increased bone antibiotic concentration for drugs with higher serum levels and longer half-lifes (cefazolin and ceforanide) was noted. Bone antibiotic concentrations were maximal within 60 minutes of drug administration. Although bone antibiotic concentrations following 2-g doses were greater than those following 1-g doses, the differences were not statistically significant. A trend toward higher bone antibiotic concentrations at hip surgery was noted, and this difference achieved statistical significance (p less than 0.05) for cefazolin. As a result of analysis of bone antibiotic concentrations, antimicrobial sensitivities, and cost, administration of 2 g of cefazolin immediately prior to operation, followed by 1 g every eight hours for 24 hours, is recommended in elective prosthetic joint surgery.