Carbon savings associated with changing surgical trends in total knee arthroplasty in England: a retrospective observational study using administrative data.

Background: Best practice pathways for common surgical procedures, including total knee arthroplasty (TKA), have the potential to improve patient outcomes and reduce carbon emissions. We aimed to estimate the reduction in carbon emissions due to changing trends in the care of patients undergoing TKA in England.

Methods: This was a retrospective analysis of Hospital Episode Statistics data from 1 April 2013 to 31 March 2022 on adults undergoing elective primary TKA in England. The carbon footprint for each patient was calculated using carbon factors for multiple steps in the pathway, including ipsilateral knee arthroscopies in the year preceding the TKA, outpatient attendances, the index TKA, revisions of the TKA performed within 180 days of the index procedure, length of hospital stay and emergency readmissions.

Results: A total of 648,861 TKA operations were identified. Over the study period, the median length of stay reduced from four to three days, the proportion of patients undergoing ipsilateral knee arthroscopies performed within a year before TKA surgery fell from 5.9% to 0.5% and the number of early revisions and emergency readmissions also fell. The per-patient carbon footprint reduced from 378.8kgCO₂e to 295.2kgCO₂e over this time. If all the study patients had the same carbon footprint as the average patient in 2021/2022, 32.4kilotons CO₂e would have been saved, enough to power 29,509 UK homes for one year.

Conclusions: Practices that were introduced primarily to improve patient outcomes can contribute to a reduction in the carbon footprint.