Does laminar airflow make a difference to the infection rates for lower limb arthroplasty: a study using the National Joint Registry and local surgical site infection data for two hospitals with and without laminar airflow.

This study compared the National Joint Registry for England, Wales, Northern Ireland and the Isle of Man (NJR) data for total hip replacements (THRs) and total knee replacements (TKRs) from Hospital A [with laminar airflow (LAF)] and Hospital B (without LAF). These hospitals were originally managed by two different trusts that subsequently merged. Consequently, the theatres in Hospital A have always had LAF and those in Hospital B had only conventional ventilation systems. As this merger happened before the establishment of the NJR, it puts us in a unique position, enabling direct comparison of the revision rates for infected hip and knee replacements between the two hospitals that follow similar infection protocols. Analysis of the NJR data showed there were no statistical differences. Of the 2234 TKRs performed at Hospital A, 16 were revised for infection, whereas 19 of the 3694 TKRs at Hospital B were revised (p < 0.33). Of the 1752 THRs at Hospital A, 5 were revised for infection, whereas this was the case for 12 of the 3163 THRs at Hospital B (p < 0.59). There was also no statistical difference when combining the figures for TKRs and THRs (p < 0.59). Our local surgical site infection (SSI) data from these two hospitals were also analysed. Again, there was no statistical difference between the two sites (p < 0.34). Using LAF has not reduced the rate of revision for infection nor it has reduced the incidence of SSI in our theatres. This is the first study comparing infection rates in two different hospitals serving similar patient populations using the NJR and SSI data. Our study questions the rationale of increasing use of LAF in routine lower limb arthroplasty. We call for greater debate and more robust studies on the subject.