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 < 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.
* Department of Medicine, St. Louis Park Medical Center, Minneapolis, Minnesota.
** Department of Orthopedic Surgery, Metropolitan Medical Center, Minneapolis, Minnesota.
† Research Laboratory, St. Louis Park Medical Center, Minneapolis, Minnesota.