Abstract
Introduction
We report the results of a prospective study of 1349 patients undergoing 1509 total knee replacements, identifying factors increasing the risk of infection.
Methods
Data were collected prospectively between October 1998 and February 2002 by a dedicated audit nurse. Pre-operative demographic and medical details were recorded. Operative and post-operative complications were noted. The definitions of surgical-site infection were based on a modification of those published by the Centre for Disease Control (CDC) in 1992. A superficial wound infection had a purulent discharge or positive culture of organisms from aseptically-aspirated fluid, tissue, or from a swab. Deep infection was counted as an infection that required a secondary procedure. Patients were seen at 6, 18 and 36 months post-operatively in a dedicated knee audit clinic and infection details recorded. The association between infection and other factors was tested by chi-squared or Mann-Whitney tests for categorised or quantitative factors respectively.
Results
18 patients (1.2% of all total knee replacements) had deep infection and a further 49 suffered a superficial infection. We found no correlation between risk of infection and age, sex, BMI, ASA grade, tourniquet time, lateral release, surgeon, transfusion or the need for catheterisation in the early post-operative period. Diabetic patients had an increased odds ratio for deep and superficial infection, but these results did not reach statistical significance. Only 3 of the 49 superficial infections went onto develop a deep infection at an average of 21 months after surgery.
Conclusion
Using modern orthopaedic surgical techniques including laminar flow theatres, systemic antibiotics and antibiotic loaded cement, the risk of infection following TKR is 1.2%. There is a mildly increased risk of infection in diabetics. Catheterisation with antibiotic cover does not increase the risk of infection.
