The carbon footprint of total knee replacements

Objective Detailed quantifications of the environmental footprint of operations that include surgery, anaesthesia, and engineering are rare. We examined all such aspects to find the greenhouse gas emissions of an operation. Methods We undertook a life cycle assessment of 10 patients undergoing total knee replacements, collecting data for all surgical equipment, energy requirements for cleaning, and operating room energy use. Data for anaesthesia were sourced from our prior study. We used life cycle assessment software to convert inputs of energy and material use into outputs in kg CO2 e emissions, using Monte Carlo analyses with 95% confidence intervals. Results The average carbon footprint was 131.7kg CO2 e, (95% confidence interval: 117.7-148.5kg CO2 e); surgery was foremost (104/131.7kg CO2 e, 80%), with lesser contributions from anaesthesia (15.0/131.7kg CO2 e, 11%), and engineering (11.9/131.7kg CO2 e, 9%). The main surgical sources of greenhouse gas emissions were: energy used to disinfect and steam sterilise reusable equipment (43.4/131.7kg CO2 e, 33%), single-use equipment (34.2/131.7kg CO2 e, 26%), with polypropylene alone 13.7/131.7kg CO2 e (11%), and the knee prosthesis 19.6kg CO2 e (15%). For energy use, the main contributors were: gas heating (6.7kg CO2 e) and heating, cooling, and fans (4kg CO2 e). Conclusions The carbon footprint of a total knee replacement was equivalent to driving 914km in a standard 2022 Australian car, with surgery contributing 80%. Such data provide guidance in reducing an operation's carbon footprint through prudent equipment use, more efficient steam sterilisation with renewable electricity, and reduced single-use waste.