Introduction: Epidemiology of Knee Arthroplasty in a Younger Patient Population

Total knee arthroplasty (TKA) is one of the most commonly performed elective surgical procedures in the USA, with an exponential growth in volume noted in the past few decades. Many studies have provided estimated future projections of TKA volume and incidence rates using different epidemiological models. Incidence rates are typically calculated as the number of TKAs during a specified time period divided by the size of the US population (using US Census Bureau data) during the same time period. This chapter assesses the most current data available as of May 2020 and discusses factors that affect models and projections for future TKA numbers in the USA. Factors such as age and gender are taken into account when available. The effect of long-term participation in athletics and sports injuries on the future development of knee osteoarthritis and potentially TKA is reviewed.