It was theorized that specific patient factors might have influenced a surgeon to use ABC in a particular orthopedic case, if it was perceived that the patient was at increased risk of infection or if there was potential for healing to be prolonged. Whether a patient had refrained from smoking tobacco was considered because the literature suggests that smoking inhibits bone healing after fracture, and smokers have a greater risk of infection than nonsmokers. Diabetes mellitus was included, as patients with diabetes have a higher risk of infection after total knee arthroplasty than patients who do not have this condition. Overall, patients with at least one immune-status factor were significantly more likely to receive ABC than those with no identified immune-status factors (p < 0.001). The orthopedic surgeons in the Calgary Health Region may be relatively conservative in making decisions about the use of ABC when only one risk factor is present, although these data should be confirmed by a larger and more robust study. Of note, patients with several immune-status risk factors did not appear to consistently receive ABC, although the sample size of this study prevented detailed analysis.

Chronic renal insufficiency also impairs a patient’s ability to recover from infection, but this condition might also make a surgeon hesitant to use an aminogly- coside for fear of systemic toxicity. Although ABC is suggested to have less potential for systemic toxicity because it is applied locally, there have been case reports of acute renal toxicity when large amounts of aminoglycosides were used in cement for joint revision; the condition improved when the ABC was removed. In this audit 4 patients were identified as having chronic renal insufficiency, of whom 2 received an aminoglycoside-containing bone cement; however, these numbers are too small to allow any conclusions.
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A limitation of this audit is that only a small, convenience sample of medical records was reviewed and the results may not represent the true usage of ABC for primary prophylaxis in the Calgary Health Region. The study is also prone to bias, since the charts were not randomly selected. In addition, arthroplasties performed at the Health Resource Centre in Calgary, Alberta, were not included in the review. The Health Resource Centre is a private surgical facility, where primary total hip arthroplasty and uncomplicated total knee arthoplasty are performed as insured services (medically necessary procedures paid for by the Alberta Health Care Insurance Plan) under contract to the Calgary Health Region. Medical records from this centre were inaccessible for the purposes of this audit, yet the number of insured procedures performed there is substantial. Based on the renewal agreement with the centre,20 it is estimated that about 700 insured hip and knee arthroplasty procedures are performed there each year.

The 2004 advisory statement from the National Surgical Infection Prevention Project 21 states that “Despite the potential benefits of antibiotic impregnated bone cement for arthroplasty, controversies remain regarding its use . . . [and] there are no established guidelines for use of these agents as prophylaxis.” Indeed, this audit of current Canadian practice has revealed that orthopedic surgeons do not seem to have a standard practice when using ABC for primary total hip and knee arthroplasty. Both benefits and risks are associated with the practice of adding antibiotics to bone cement, and continuous review of practice variation would be beneficial. buy cialis soft tabs

A summary of this study was presented and discussed at a meeting of the Calgary Health Region’s Surgical Site Infection Committee, which was attended by orthopedic nurses, an orthopedic surgeon from the Division of Joint Reconstruction, an infectious diseases pharmacist, and an infection control and prevention practitioner, among others. In this way, awareness of the cryptic use of antibiotics was raised, and education about this practice was provided. Although the literature suggests that ABC offers modest improvements in rates of surgical site infection with primary arthroplasty, the general impression of at least 2 committee members was that lowering the already-low infection rate would be desirable, regardless of the lack of pharmacoeconomic data. The results of the study were also presented to the Division of Infectious Diseases. Although some practitioners in that department recognized (through medical record notations) that use of ABC was occurring, most did not realize the extent of its use. Discussion with the Subdivision of Reconstructive Surgery is under way to try to standardize the selection and criteria for the use of ABCs in orthopedic surgery.