Surveillance of surgical site infection (SSI) in orthopaedic surgery became mandatory in England in April 2004 [1].

The requirements of the mandatory scheme are that all public hospitals performing orthopaedic surgery must undertake surveillance for a minimum of three consecutive months annually, in at least one of the orthopaedic categories: total hip prosthesis, hip hemiarthroplasty, knee prosthesis or open reduction of long bone fracture [2]. This flexible approach acknowledges the resources required to undertake this type of surveillance and enables hospitals to target surveillance activity in more than one category of procedures.

For valid comparisons to be made between hospitals, it is essential that standardised data data are collected. The standard methods for collecting and reporting data are described in a detailed protocol [3] and are covered by a training programme offered quarterly. A key aim of the surveillance service provided by the Surgical Site Iinfection Surveillance Service (SSISS) is to enable hospitals to compare their rates of SSI with other participating hospitals and use this information to evaluate local practice, investigate and institute changes where their results indicate this may be necessary. At the end of each quarterly surveillance period, each hospital is sent an individual report that contains their results compared to the aggregated data.

This first report included data on 42 242 procedures collected by 146 hospitals. The results showed that overall the rates of SSIs in orthopaedic surgery are low and comparable with hospitals in other European countries [4,5]. The risk of developing an SSI increased with the age of the patient and the number of underlying risk factors present. Most infections only affected the superficial layers of the wound but one quarter involved the deeper tissues or joint itself. Of particular concern is that that one third of the SSIs were reported to be caused by methicillin resistant Staphylococcus aureus (MRSA).

One of the major difficulties in making reasonable comparisons between hospitals is that the precision with which the SSI rate can be estimated is dependant on the number of surgical procedures done at the hospital and also depends on the length of time the hospital has participated in the surveillance. In order to adjust for the number of procedures, SSIs are plotted against the number of procedures. Control limits set at 95% and 99% have then been used to indicate those hospitals whose rates are unusually high and require further investigation [6].

All the hospitals that have been identified as having comparatively high rates of SSI in the mandatory surveillance scheme have started an investigation and have action plans in place to tackle any problems identified. This underlines the value of the surveillance in helping hospitals recognise and resolve problems in clinical practice and ensure that good standards of infection control in relation to orthopaedic surgery are in place.

Surgical Site Infection Surveillance Service (SSISS) has recently published the first annual report http://www.dh.gov.uk/PolicyAndGuidance/HealthAndSocialCareTopics/HealthcareAcquiredInfection/fs/en and http://www.hpa.org.uk/infections/topics_az/hai/SSI_mandatory_0405report.pdf