Introduction. Operating theatre airflow can be measured using pulsed lasers (particle image velocimetry) but the process is difficult to do in 3D. Cup, vane or hot wire anemometers provide only 2D information. 3D measurements enable better understanding of airflow. Patients/Materials & Methods. We used a Windmaster ultrasound 3D anemometer (Skyview systems), which uses three ultrasound transmitters to measure velocity in XYZ planes, with a sampling rate of 32 Hz. Post processing was done using MATLAB. An operating theatre with an Howorth Exflow canopy was studied. Equipment, including lights, was moved. A 50 cm grid was marked, and measurements were made at intervals up to the ceiling. Door opening was observed within the clean zone and the peripheral zone, next to the door and on the opposite side of the room. Anaesthetic screens were studied during operating. Airflow was visualised initially using video of smoke puffs and subsequently measured using the aeronometer. Results. In the upper part of the ultraclean canopy air velocity was 0.34 m/s with a standard deviation of 0.02 m/s, indicating an almost constant velocity. In the periphery there was more turbulence and horizontal air movement. Door opening had no effect on air movements in the clean zone. In the periphery there was an increase in horizontal airflow when the doors are closed. There is a pattern of upward airflow against an anaesthetic screen. This is unlikely to be caused by warming blankets. If the partial wall of the enclosure is lowered this results in a fast washout of air towards the anaesthetist. Discussion. Traditional anaesthetic screens may interfere with airflow. Door opening is a lesser effect. Conclusion. The 3D anemometer enables detailed mapping of airflow within an ultra clean air operating theatre. The data obtained will enable the construction of more accurate computational fluid dynamic models of operating theatres

As a result of laser imaging studies in an ultraclean theatre we concluded that obstructions to horizontal airflow at the periphery might produce areas of high particulate residence times. High residence times may allow a higher proportion of infected particles to land. We decided to investigate this effect by placing settle plates in defined positions on instrument trays during surgery.

In an initial study contamination was 0.25 colonies/plate/hour. When the surgeon, assistant and scrub person all used a body exhaust system the contamination rate was 0.04 colonies/plate/hour. We then organised the instrument tables with two large tables orientated so that the scrub person did not have to stand between the airflow and the table. We placed plates on both trays with the locations recorded.

With the instrument trolleys in optimised positions the contamination rate remained consistently at 0.04 colonies/plate/hour. An animation was produced showing how the bacterial colonies appeared over 18 hours of surgery. The majority of the contamination occurred on the surgeons’ side trolley at the opposite end of the trolley to the surgeon.

Ultraclean enclosures in the UK are specified by HTM03-01, which sets a standard of <10 cfu/cubic meter measured by active air sampling. The measurement does not however take place during surgery, as it is very difficult to perform air sampling during surgery. There is a reasonable correlation between air contamination and settle plates so they are a viable method for during surgery monitoring.

In a modern operating enclosure, using body exhausts, our contamination rate compares favourably to the fourth phase of Charnley's classic study in which he used 300 air changes/hour in the prototype closure. The rate compares favourably to the multi-centre Italian GISIO-ISChIA study. The contamination rate achieved could form a basis for comparative audits based on realistic during surgery monitoring.

Infection following total hip or knee arthroplasty is a serious complication. We noted an increase in post-operative infection in cases carried out in a temporary operating theatre. We therefore compared those cases performed in standard and temporary operating theatres and examined the deep periprosthetic infection rates.

A total of 1233 primary hip and knee arthroplasties were performed between August 2012 and June 2013. 44% were performed in temporary theatres. The two groups were matched for age, sex, BMI and ASA grade.

The deep infection rate for standard operating theatres was 0/684 (0%); for temporary theatres it was 8/539 (1.5%); p=0.001.

Use of a temporary operating theatre for primary hip and knee arthroplasty was associated with an unacceptable increase in deep infection. We do not advocate the use of these theatres for primary joint arthroplasty.

Aims

Using a systematic review, we investigated whether there is an increased risk of post-operative infection in patients who have received an intra-articular corticosteroid injection to the hip for osteoarthritis prior to total hip arthroplasty (THA).

The World Health Organization (WHO) and the Centre for Disease Control and Prevention (CDC) recently published guidelines for the prevention of surgical site infection. The WHO guidelines, if implemented worldwide, could have an immense impact on our practices and those of the CDC have implications for healthcare policy in the United States.

Our aim was to review the strategies for prevention of periprosthetic joint infection in light of these and other recent guidelines.

Cite this article: Bone Joint J 2017;99-B(4 Supple B):3–10.