Modeling the impact of obesity on cost of hip and knee arthroplasty

•In 2015, total knee and hip arthroplasty cost Irish public hospitals €52 million.•Age continues to be a cost driver of total knee and hip arthroplasty–related costs.•Obesity was associated with 43% of knee and 20% of hip replacement costs.•Better data would improve the accuracy of Irish cost estimates.•Investments in obesity control may benefit osteoarthritis outcomes and lower costs.