Population growth, ageing and obesity do not sufficiently explain the increased utilization of total knee replacement in Australia

Background The utilization of total knee replacement (TKR) has increased significantly. The objective of this study was to assess the impact of changes in population demography (population growth, ageing and gender) and body mass indices (BMIs) on the additional volume of knee replacement surgery undertaken in Australia. Methods Using national data, we compared estimates based on changes in population demography and BMIs to the reported increase in TKR between 2007 and 2017. The costs of additional surgery were estimated using the National Hospital Cost Data Collection. Results An additional 25 814 TKRs were performed in 2017 compared to 2007. Contributions from population growth, ageing and changing BMIs were 27.1%, 10.4%, and 6.3%-15.3%, respectively. Other drivers contributed between 47.2% and 56.2%, representing 12 176-14 506 TKRs at a financial cost of A$320.9 million to A$382.3 million per year in 2017. Conclusion The volume of additional surgery being performed considerably exceeded estimates based on changing population demography and rising rates of obesity. The other drivers of additional TKR utilization will likely have significant implications for the health budget and warrant further investigation. This may involve an examination of the current indications for surgery and the cost-effectiveness of TKR in various settings, reviewing patient expectations and preferences, and assessing the impact of policies which relate to the funding and provision of TKR.