August 2004 Bulletin

Use of antibiotic prophylaxis in primary TJA

AAOS Board adopts advisory statement

By Jason H. Calhoun, MD, FACS

Numerous studies have shown that prophylactic antibiotics reduce the incidence of infection after orthopaedic surgery in patients without known infection. The use of prophylactic antibiotics is now considered routine for primary total joint arthroplasty (TJA). There is strong evidence that supports clear recommendations on the use of antibiotic prophylaxis, although some resistance to implementation remains.

To clarify the evidence and encourage implementation, the AAOS Board of Directors recently adopted an Advisory Statement containing recommendations for intravenous antibiotic prophylaxis in primary TJA. In developing the recommendations, the AAOS Infections Committee studied the relevant literature and collaborated with leading medical organizations to identify best practices for preventing surgical site infections.

Developing measures

Since August 2002, the Academy has participated in the National Surgical Infection Prevention (SIP) Project, a joint venture between the Centers for Medicare & Medicaid Services (CMS) and the Centers for Disease Control and Prevention (CDC). The goal of SIP is to decrease the morbidity and mortality associated with postoperative surgical site infections by promoting appropriate selection and timing of administration of prophylactic antibiotics.

A panel of experts in surgical infection prevention, hospital infection control and epidemiology—including two members of the AAOS Infections Committee—developed three performance measures for national surveillance and quality improvement: 1) the proportion of patients who receive prophylactic antibiotics consistent with current recommendations; 2) the proportion of patients who receive antibiotic prophylaxis within one hour before the surgical incision; and 3) the proportion of patients whose prophylactic antibiotics were discontinued within 24 hours of the end of surgery. The results of this surveillance are included in an advisory statement issued by SIP and published in the June 15, 2004, issue of Clinical Infectious Diseases (

Improper use increases risk

Preliminary data indicates that antibiotic prophylaxis is not always administered in a manner that is supported by scientific evidence. Inappropriate use of antibiotics not only fails to prevent postoperative infections, it contributes to antibiotic resistance, increases the risk of adverse reactions, predisposes the patient to infections and increases healthcare costs.

The new AAOS Advisory Statement was developed by the Infections Committee and reviewed by the Patient Safety Committee, the Council on Research and the Board of Directors.

The Academy recommends the following evidence-based practices for the appropriate use of intravenous antibiotic prophylaxis in primary TJA:

The antibiotic used for prophylaxis should be carefully selected, consistent with current recommendations in the literature, taking into account the issues of resistance and patient allergies.

Currently, cefazolin or cefuroxime are the preferred antibiotics for patients undergoing orthopaedic procedures. Clindamycin or vancomycin may be used for patients with a confirmed -lactam allergy. Vancomycin may be used in patients with known colonization with methicillin resistant Staphylococcus aureus (MRSA) or in facilities with recent MRSA outbreaks. In multiple studies, exposure to vancomycin is reported as a risk factor in the development of vancomycin-resistant enterococcus (VRE) colonization and infection. Therefore, vancomycin should be reserved for the treatment of serious infection with -lactam-resistant organisms or for treatment of infection in patients with life-threatening allergy to -lactam antimicrobials.

Timing and dosage of antibiotic administration should optimize the efficacy of the therapy.

Prophylactic antibiotics should be administered within one hour prior to skin incision. Vancomycin should be started within two hours prior to incision because it has an extended infusion time. If a proximal tourniquet is used, the antibiotic must be completely infused before the tourniquet is inflated. Dose amount should be proportional to patient weight; doses of cefazolin should be doubled for patients weighing more than 80 kg. Additional intraoperative doses of antibiotic are advised if:

  1. The duration of the procedure exceeds one to two times the antibiotic’s half-life.

  2. There is significant blood loss during the procedure.

General guidelines for frequency of intraoperative administration can be found in the Advisory Statement.

Duration of prophylactic antibiotic administration should not exceed the 24-hour postoperative period.

Prophylactic antibiotics should be discontinued within 24 hours of the end of surgery. Medical literature does not support the continuation of antibiotics until all drains or catheters are removed, nor does it provide any evidence of benefit when antibiotics are continued beyond 24 hours.

Although these recommendations will be appropriate for most patients at the majority of facilities, sound clinical judgment must be exercised to recognize those unusual cases in which an alternative approach is necessary.

To read the Advisory Statement in its entirety, visit the AAOS web site at

Jason H. Calhoun, MD, FACS, is chairman of the AAOS Infections Committee as well as chairman and J. Vernon Luck Distinguished Professor of Orthopaedic Surgery at the University of Missouri, Columbia. He can be reached at

Implant infections costly

According to a study published in the April 1, 2004 issue of The New England Journal of Medicine, approximately one half of the 2 million cases of nosocomial infection that occur each year in the United States are associated with indwelling devices. Although less common than infections related to catheters, infections associated with surgical implants are generally more difficult to manage because they require a longer period of antibiotic therapy and repeated surgical procedures.

According to the study, 2 percent of the 600,000 joint prosthesis and 5 percent of the 2 million fracture fixation devices implanted each year in the U.S. result in an infection. With the average cost of treatment for these infections estimated at $30,000 and $15,000 respectively, the cost of such infections—in dollars alone—is astronomical.

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