(HealthDay News) – Prevalence estimates show that approximately 4.7% of the US population aged ≥50 years currently has an intact primary total knee replacement (TKR), according to a study presented at the annual meeting of the American Academy of Orthopaedic Surgeons, held from Feb. 7–11 in San Francisco.

Alexander M. Weinstein, from the Boston University School of Public Health, and colleagues investigated the number of individuals in the United States living with knee implants. Using a state-transition, computer-simulation model, the prevalence of primary TKR was estimated, stratified by age and gender. To calculate the number of Americans currently living with an intact primary TKR, prevalence estimates were combined with 2009 census data.

The researchers found that more than 4.5 million Americans have an intact primary TKR, representing 4.7% of the population aged ≥50 years. TKR prevalence is 5.3% in females and 4.1% in males. Among adults aged 60–69 years, 4.9% of women and 4.1% of men have had at least one knee replacement, with the percentages increasing to 8.2% and 7.1%, respectively, for those aged 70–79 years. Among adults >80 years, approximately 10% have had at least one knee replacement.

“Among persons older than 50 years of age, TKR has become considerably more prevalent than rheumatoid arthritis or congestive heart failure. Knowledge of TKR prevalence is useful in planning health services specific to the population living with TKR,” the authors write.

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