Infection is disastrous in arthroplasty surgery and requires multidisciplinary treatment and debilitating revision surgery. Between 80-90% of bacterial wound contaminants originate from colony forming units (CFUs) present in operating room air, originating from bacteria shed by personnel present in the operating environment. Steps to reduce bacterial shedding should reduce wound contamination. These steps include the use of unidirectional laminar airflow systems and the introduction of theatre attire modelled on this principle (e.g. total body exhaust suits). Our unit introduced the use of the Stryker Sterishield Personal Protection System helmet used with laminar flow theatre systems. This study compares an enclosed helmet system used with standard gowns, with standard hood and mask attire. 12 simulated hip arthroplasties were performed, six using disposable sterile impermeable gown, hood and mask and a further 6 using a Sterishield helmet and hood. Each 20 minute operation consisted of arm and head movements simulating movements during surgery. Air was sampled at wound level on a sterile draped operating table using a Casella slit sampler, sampling at 700l/minute. Samples were incubated on Blood agar for 48 hours at 37°c and the CFUs grown were counted.Introduction
Method
Pseudotumours (soft-tissue masses relating to the hip joint) following metal-on-metal hip resurfacing arthroplasty (MoMHRA) have been associated with elevated serum and hip aspirate metal ion levels, suggesting that pseudotumours occur when there is increased wear. This study aimed to quantify the wear of implants revised for pseudotumours and a control group of implants revised for other reasons of failure. A total of 30 contemporary MoMHRA implants in two groups were investigated: (1) 8 MoMHRA implants revised due to pseudotumour; (2) 22 MoMHRA implants revised due to other reasons of failure. The linear wear of retrieved implants was measured using a Taylor-Hobson Roundness machine. The average linear wear rate was defined as the maximum linear wear depth divided by the duration of the implant In comparison with the non-pseudotumour implant group, the pseudotumour implant group was associated with: (1) significantly higher median linear wear rate of the femoral component: 8.1 um/year (range 2.75-25.4 um/year) vs. 1.97 um/year (range 0.82-13.00 um/year), p=0.002; and (2) significantly higher median linear wear rate of the acetabular component: 7.36 um/year (range 1.61-24.9 um/year) vs. 1.28 um/year (range 0.18-3.33 um/year), p=0.001. Wear on the acetabular cup components in the pseudotumour group always involved the edge, indicating edge-loading of the bearing. Significantly greater linear wear rates of the MoMHRA implants revised due to pseudotumour support the
