Estimating the burden of total knee replacement in the United States.
BACKGROUND
In the last decade, the number of total knee replacements performed annually in the United States has doubled, with disproportionate increases among younger adults. While total knee replacement is a highly effective treatment for end-stage knee osteoarthritis, total knee replacement recipients can experience persistent pain and severe complications. We are aware of no current estimates of the prevalence of total knee replacement among adults in the U.S.


METHODS
We used the Osteoarthritis Policy Model, a validated computer simulation model of knee osteoarthritis, and data on annual total knee replacement utilization to estimate the prevalence of primary and revision total knee replacement among adults fifty years of age or older in the U.S. We combined these prevalence estimates with U.S. Census data to estimate the number of adults in the U.S. currently living with total knee replacement. The annual incidence of total knee replacement was derived from two longitudinal knee osteoarthritis cohorts and ranged from 1.6% to 11.9% in males and from 2.0% to 10.9% in females.


RESULTS
We estimated that 4.0 million (95% confidence interval [CI]: 3.6 million to 4.4 million) adults in the U.S. currently live with a total knee replacement, representing 4.2% (95% CI: 3.7% to 4.6%) of the population fifty years of age or older. The prevalence was higher among females (4.8%) than among males (3.4%) and increased with age. The lifetime risk of primary total knee replacement from the age of twenty-five years was 7.0% (95% CI: 6.1% to 7.8%) for males and 9.5% (95% CI: 8.5% to 10.5%) for females. Over half of adults in the U.S. diagnosed with knee osteoarthritis will undergo a total knee replacement.


CONCLUSIONS
Among older adults in the U.S., total knee replacement is considerably more prevalent than rheumatoid arthritis and nearly as prevalent as congestive heart failure. Nearly 1.5 million of those with a primary total knee replacement are fifty to sixty-nine years old, indicating that a large population is at risk for costly revision surgery as well as possible long-term complications of total knee replacement.
Orthopaedic and Arthritis Center for Outcomes Research, Brigham and Women's Hospital, Boston, MA 02115, USA.
Alexander M
AM
Weinstein
Benjamin N
BN
Rome
William M
WM
Reichmann
Jamie E
JE
Collins
Sara A
SA
Burbine
Thomas S
TS
Thornhill
John
J
Wright
Jeffrey N
JN
Katz
Elena
E
Losina
D000328:Adult; D017677:Age Distribution; D000368:Aged; D000369:Aged, 80 and over; D019645:Arthroplasty, Replacement, Knee / Q000706:statistics & numerical data*; D003198:Computer Simulation; D017281:Cost of Illness; D018450:Disease Progression; D005260:Female; D006801:Humans; D015994:Incidence; D008137:Longitudinal Studies; D008297:Male; D008875:Middle Aged; D008954:Models, Biological; D020370:Osteoarthritis, Knee / Q000453:epidemiology / Q000601:surgery*; D012086:Reoperation / Q000706:statistics & numerical data; D012306:Risk; D017678:Sex Distribution; D014481:United States / Q000453:epidemiology