7 million Americans living with artificial knee or hip

More than 7 million Americans are living with an artificial knee or hip, which may have significant future implications in terms of the need for ongoing patient care, according to new research.

Two related studies also found a growing incidence of adults younger than age 65 undergoing total knee replacement (TKR) and total hip replacement (THR) surgeries, and a potential underutilisation of these procedures in some segments of the population.

Researchers reviewed THR and TKR incidence rates, mortality rates and relative mortality rates (the difference in survival between THR and TKR patients and the general population), over a 40-year time period, to estimate 2010 prevalence rates according to age, sex and time since surgery.

Researchers found that approximately 0.8 per cent of Americans are living with a hip replacement, and 1.5 per cent with a knee replacement.

More women are living with prosthetic hips and knees than men, they found. The study also shows that prevalence of THR and TKR among adults aged 50 and older is as high as 2.3 and 4.6 per cent, respectively.

The prevalence of THR rises to nearly 6 per cent by 80 years of age. The prevalence of TKR rises to nearly 10 per cent by 80 years of age.

The states with the highest number of THR and TKR patients are California, Florida and Texas; the two states with the lowest numbers are Alaska and Hawaii, the study found."This study shows that around 7 million Americans have a hip or knee replacement," said Daniel Berry, professor of orthopaedics at Mayo Clinic and the senior study author.

"This large number highlights how these operations have kept a substantial part of our population mobile despite severe arthritis, something that wouldn't have been possible before these technologies were available.

"These relatively high prevalence estimates also highlight the significant ongoing need to care for all of the patients with total hip and knee replacement," said Berry.