Changing incidence of primary total hip arthroplasty and total knee arthroplasty for primary osteoarthritis.

This study reports on the incidence of primary total hip arthroplasty (THA) and total knee arthroplasty (TKA) for primary osteoarthritis in Australia. Age-specific and gender-specific numbers for Australia, 1994 through 1998, and South Australia, 1988 through 1998, were obtained. Incidences were calculated per 100,000 population. In Australia, primary THA increased from 50.9/10(5) (1994) to 60.9/10(5) (1998). TKA increased from 56.4/10(5) to 76.8/10(5). Stratified by age and gender, changes in incidence for South Australia with respect to time were tested using regression analysis. South Australia showed a significant increase in the overall incidence of THA (P=.012) and TKA (P<.001), although this was not uniform across all age groups. No significant gender differences were found. The incidence of THA is increasing, and the incidence of TKA is increasing at a greater rate.