Risk factors for prosthetic hip and knee infections according to arthroplasty site
Introduction
Infection of the prosthetic joint is a significant complication of arthroplasty, occurring at a rate of 2–3% per year in most series.1 These infections are associated with significant morbidity and mortality.2 In addition, the financial cost to the health system is considerable, with estimated hospital costs of US $96,166 per patient requiring revision arthroplasty for infection.3 Over time, the number of people requiring prosthetic joint replacement is expected to increase; US Medicare data predict that by 2030 the number of patients undergoing primary hip and knee replacement will increase by 174% and 673% respectively.4 Identifying patients at increased risk of prosthetic joint infection is important: it could inform preoperative assessment to optimise patient comorbidity and might increase the diagnostic acumen of clinicians.
Current epidemiological studies examining clinical risk factors do not usually take the site of the prosthetic joint into account. Risk factors may vary according to which joint is replaced.
Section snippets
Methods
This case–control study was designed to examine the impact of patient comorbidity, operative and postoperative factors on the risk of subsequent prosthetic joint infection with particular reference to the joint replaced. The study was conducted at a metropolitan university-affiliated tertiary hospital in Australia. This orthopaedic unit is currently staffed by 17 orthopaedic surgeons performing over 1200 prosthetic joint replacements per year. The study population consisted of all patients who
Results
Between 1 January 2000 and 31 January 2007, 63 patients (27 having knee replacements and 36 hip replacements) developed a prosthetic joint infection. The demographic characteristics of cases and controls are shown in Table II.
The mean interval between arthroplasty and diagnosis of prosthetic joint infection was 54 days (range: 5–277 days). Causative pathogens involved in the prosthetic joint infections in the cases identified by deep, intraoperative tissue specimens are shown in Table III. In
Discussion
The results of this study suggest that risk factors for prosthetic joint infection differ according to the joint replaced. Therefore grouping all joint replacements for analysis may miss some relevant risk factors. Superficial infection and wound discharge were associated with the development of prosthetic joint infection irrespective of arthroplasty site. The association between hip arthroplasty and obesity has been delineated previously, with studies showing that morbidly obese patients have
Acknowledgements
Assistance with study design and statistical analysis was provided by Dr N.M. Peel, Australasian Centre on Ageing, University of Queensland.
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