Background — The rates of total joint arthroplasty (TJA) of the hip and knee have increased in North America over the last decade. While initially designed for elderly patients (>70 years of age), several reports suggest that an increasing number of younger patients are undergoing joint replacements. This suggests that more people are meeting the indication for TJA earlier in their lives. Alternatively, it might indicate a broadening of the indications for TJA.
Methods — The researchers used the administrative databases available at the Healthcare Cost and Utilization Project (HCUP) and the Institute for Clinical Evaluative Sciences (ICES) to determine the rates of TJA of the hip and knee in the United States, and Ontario, Canada, respectively. The researchers determined the crude rates of THA and TKA in both areas for four calendar years (2001, 2003, 2005 and 2007). The researchers also calculated the age- and sex-standardised rates of THA and TKA in both areas for each time period, and compared the age distribution of TJA recipients between the US and Ontario, and within each area over time.
Results — The crude and standardised rates of THA and TKA increased over time in both the US and Ontario. The crude rates of THA were higher in the US in 2001 and 2003, but were not significantly different from the rate in Ontario in 2005 and 2007. The crude rates of TKA were consistently higher in the US for all time periods. In addition, the US consistently had more THA and TKA recipients in 'younger' age categories (<60 years of age). While the age- and sex-standardised rates of TKA were greater in the US in all time periods, the relative increase in rates from 2001 to 2007 was greater in Ontario (US - 59%, Ontario - 73%). For both the US and Ontario, there was a significant shift in the demographic of THA and TKA recipients to younger patients (p < 0.0001).
Conclusions — The utilisation of primary hip and knee arthroplasty has increased substantially in both the US and Ontario in the period from 2001 to 2007. This increase has been predominantly in knee replacements. The demographics of joint replacement recipients has become younger, with substantial increases in the prevalence of patients <60 years old amongst TJA recipients, and significant increases in the incidence of TJA in these age groups in the general population, in both the US and Ontario.