Prevention of infection after total joint replacement

An experiment was done in dogs to evaluate how efficient each of several techniques was in preventing infection after a total joint arthroplasty. The techniques that were studied were intraoperative irrigation with saline solution or with antimicrobial solution, perioperative systemic administration of antibiotics, and the addition of an antibiotic to bone cement. Irrigation with saline solution did not reduce the incidence of infection. A slight reduction was found after irrigation with neomycin solution and after systemic administration of cefazolin solution. The use of bone cement containing gentamicin caused a statistically significant reduction in the rate of infection; in fact, no infection developed in any animal that was treated with bone cement containing gentamicin. There was excellent but not absolute correlation between findings on culture that indicated the presence of infection and histological evidence of inflammation. The incidence of infection after total joint replacement is not high, but when infection occurs it is often disastrous. In a previous investigation3’ , we evaluated the effect in dogs of various implants for total joint replacement on the mcidence of infection with Staphylococcus epidermidis, Staphylococcus aureus, and Escherichia coli. The implants that we studied were made of stainless steel, cobalt-chromium alloy, high-molecular-weight polyethylene, and polymethylmethacrylate. Replacements using these implants were found to be associated significantly more frequently with infection compared with procedures in which no implant was inserted. Polymethylmethacrylate that polymerized in vivo was found to be associated more frequently with infection than were the other materials. Early clinical studies revealed relatively high rates of infection after total hip replacement, and it was suspected that polymethylmethacrylate was responsible67. Therefore, much effort has been spent in preventing bacteria from reaching the operative site. Special systems for handling air were devised, intraopera* No benefits in any form have been received or will be received from a commercial party related directly or indirectly to the subject ofthis article. Funds were received in total or partial support of the research or clinical study presented in this article. The funding source was National Institutes of Health Grant 5ROl AM24007-04. t Department of Orthopaedics, Box J-246, University of Florida College of Medicine, Gainesville, Florida 32610. University of Florida College of Liberal Arts and Sciences, Gainesville, Florida 32610. tive antimicrobial irrigating solutions were advocated, perioperative antibiotics were administered systemically, and bone cement that had been impregnated with antibiotics was suggested for routine prophylaxis245 4.19. 22.27 In the present study, we used essentially the same cxperimental animal model that we used in our previous study3’ . We evaluated the efficacy of four techniques to reduce the incidence of infection with Staphylococcus aureus, Staphylococcus epidermidis, and Escherichia coli after total joint replacement using bone cement. The methods included: intraoperative irrigation with normal saline solution or with antimicrobial solution, perioperative administration of antibiotics systemically, and the addition of an antibiotic to the bone cement. Experimental Design Methods Control groups: In the first control group, which contamed sixteen animals (sham controls), both femoral canals were reamed, but no bacteria and no polymethylmethacrylate were introduced. The purpose of this group was to develop operative techniques. In the second type of control, inocula of bacteria were inserted into both femoral canals. In other groups, both bacteria and polymethylmethacrylate in the dough stage were introduced into the femoral canal by syringe. The numbers of femora receiving each experimental treatment are shown in Table I. Experimental groups: In the group that had irrigation with saline solution, after instillation of the bacterial suspension the wound was left open for five minutes. Then the wound, including the femoral canal, was irrigated for two minutes with 500 milliliters of normal saline solution. Polymethylmethacrylate in the dough stage was then injected into the femoral canal. In the group that had irrigation with neomycin solution, after instillation of the bacterial suspension the wound was left open for five minutes and then it and the femoral canal were irrigated with 500 milliliters of 0.5 per cent neomycin solution for two minutes. Polymethylmethacrylate in the dough stage was then injected into the femoral canal. In the group that had systemic administration of antibiotics, thirty minutes before the surgical incision each animal received twenty-five milligrams of ccfazolin per kilogram of body weight intravenously over a period of five minutes. Then, beginning at the time when the incision was made, an additional twenty-five milligrams