The Department of Health and the Public Health Laboratory Service established the Nosocomial Infection National Surveillance Scheme in order to standardise the collection of information about infections acquired in hospital in the United Kingdom and provide national data with which hospitals could measure their own performance. The definition of superficial incisional infection (skin and subcutaneous tissue), set by the Center for Disease Control (CDC), should meet at least one of the defined criteria which would confirm the diagnosis and determine the need for specific treatment.

We have assessed the interobserver reliability of the criteria for superficial incisional infection set by the CDC in our current practice. The incisional site of 50 patients who had an elective primary arthroplasty of the hip or knee was evaluated independently by two orthopaedic clinical research fellows and two orthopaedic ward sisters for the presence or absence of surgical-site infection. Interobserver reliability was assessed by comparison of the criteria for wound infection used by the four observers using kappa reliability coefficients. Our study demonstrated that some of the components of the current CDC criteria were unreliable and we recommend their revision.

In our region, we found six different radiological configurations of cannulated hip screws fixation in patients with intracapsular fracture of the femoral neck (AO type 3,1,B). These configurations, produced at the time of the screws insertion were I: Triangular, consisted of two parallel screws with a third screw placed either superiorly, inferiorly, anteriorly or posteriorly. II: Two or three screws in a vertical line. Current literature suggests that parallel lag screws and subchondral fixation are important for stable fixation, but there are no current guidelines about the optimum configuration to achieve the best fixation.

In a laboratory setting, using standard synthetic bones and ordinary AO cannulated hip screws, six different configurations were fashioned similar to clinical practice. Each specimen was subjected to a single progressive vertical load until failure. Displacement curves, in relation to the load (peak and ultimate), were recorded on the computer based data acquisition system.

The most significant result of the study was that there is a significant difference between the superior ‘single screw triangle’ [mean difference 627 (Newton), 95% CI (66.72, 1187.28)] and ‘two screws vertical’ configurations [mean difference 744 (Newton), 95%CI (183.72, 1304.28)]. No other significant differences were detected.

If cannulated hip screws are chosen for internal fixation of femoral neck fractures we would, based on our study, recommend the use of triangular configurations with two parallel screws and a third screw placed either anteriorly, posteriorly, superiorly or inferiorly as they afford better strength and stability of fixation. The configuration of two or three vertical screws should be avoided as they provide lower grade of stability and a high incidence of failure. This suggests surgical technique can influence mechanical stability and thus outcome. This needs to be emphasized, particularly during training, in the hope of improving overall results in the future.