Liquid gentamicin in bone cement spacers: in vivo antibiotic release and systemic safety in two-stage revision of infected hip arthroplasty.
BACKGROUND
Powdered antibiotics are widely used in acrylic bone cement. Liquid antibiotics, however, have rarely been employed. This study investigated the application of liquid gentamicin, a much less costly antibiotic with a broad antimicrobial spectrum, in bone cement to treat musculoskeletal infections.


METHODS
Forty-two patients undergoing two-stage revision hip arthroplasty for periprosthetic infection were managed with an interim cement spacer loaded with liquid gentamicin (480 mg per 20 mL pack of cement monomer) with or without vancomycin (3.0 g per 40 g pack cement polymer). Serum and aliquots of drainage collected after the first-stage surgery; joint fluid obtained at the time of the second-stage surgery were analyzed for antibiotic concentrations and bioactivity. Antibiotic levels in the peripheral blood and renal function were also monitored.


RESULTS
Antibiotic levels in joint fluid peaked on the first day after implantation of the spacer and then gradually declined during the first week, with levels of gentamicin and vancomycin reached 43.6 mg/L +/- 12.3 mg/L and 485.5 mg/L +/- 103.5 mg/L, respectively. Bioassay confirmed the antimicrobial activity of the released antibiotics. The systemic antibiotic concentrations were below detectable levels in the majority of patients, and no nephrotoxicity was noted. At a mean 87 days after implantation, antibiotic concentrations in joint fluid remained clinically effective (gentamicin, 5.1 mg/L +/- 2.2 mg/L and vancomycin, 21.6 mg/L +/- 8.5 mg/L).


CONCLUSIONS
Incorporation of liquid gentamicin in bone cement spacers led to effective drug delivery with systemic safety. Substantial health care dollars could be saved by the use of liquid gentamicin in bone cement to treat musculoskeletal infections.
Hsieh
Pang-Hsin
PH
Department of Orthopedics, Chang Gung Memorial Hospital, Taoyuan, Taiwan. hsiehph@adm.cgmh.org.tw
Huang
Kuo-Chin
KC
Tai
Ching-Lung
CL
D000368:Aged; D001682:Biological Availability; D004359:Drug Therapy, Combination; D005260:Female; D005839:Gentamicins / Q000493:pharmacokinetics / Q000627:therapeutic use*; D006622:Hip Prosthesis; D006801:Humans; D007677:Kidney Function Tests; D008297:Male; D008657:Metabolic Clearance Rate / Q000502:physiology; D008768:Methylmethacrylates / Q000627:therapeutic use*; D008875:Middle Aged; D016459:Prosthesis-Related Infections / Q000000981:diagnostic imaging / Q000601:surgery*; D011859:Radiography; D012086:Reoperation; D016896:Treatment Outcome; D014640:Vancomycin / Q000008:administration & dosage / Q000493:pharmacokinetics
D005839:Gentamicins; D008768:Methylmethacrylates; C030159:gentamicin-polymethylmethacrylate bead; D014640:Vancomycin