Reasons for the Growing Number of Knee Replacements

You may be surprised to find out that the number of knee replacements in adults ages 45 to 65 tripled in the last 10 years. What could account for this increase? Researchers at Brigham and Women's Hospital in Boston, Massachusetts may have found the answer.

Their research uncovered the following surprising statistics:

  • Over 600,000 total knee replacements are being done every year in the United States.
  • A total of nine billion dollars was spent on total knee replacements in one year (2008).
  • Total knee replacement is one of the top 10 fastest growing procedures in this country.
  • Over 40 per cent (41 per cent) of the adults getting knee replacements are between the ages of 45 and 65. The rest are over 65.
  • The number of knee replacements done each year is increasing in all age groups.
  • With the aging baby boomers and rising numbers of obese adults, these numbers are expected to continue to rise.
  • From their review of nationwide data from hospitals, the authors present an important finding. They say that rising rates of obesity and the growing number of older adults just aren't enough to explain such an explosion in the numbers of total knee replacements being done. Naturally, the question comes up: what other factors can account for this huge increase in total knee replacements?

A closer look at patient data showed that severe knee osteoarthritis is still the most common diagnosis (and reason for knee joint replacement). They did find an association between aging, obesity, and joint replacement. National statistics show that the number of adults medically classified as obese increased from 29.6 per cent to 33 per cent between the year 2000 and 2008.

Further analysis showed that increased use of knee replacements may be linked with expanding indications. This means that surgeons are finding greater uses for knee replacements than just severe osteoarthritis in older adults.

For example, sports-related injuries early in life have been shown to develop later into joint arthritis when those folks are in their 40s and 50s. This might account for the increasing numbers of knee replacements in the 45 to 65 age bracket. Increased athletic and sports participation in general may be contributing to joints wearing out earlier than for our grandparent's generation.

Years ago, surgeons were hesitant to give someone a knee replacement knowing that the implant might only last 10 to 15 years. They tried to wait until that person was older so the implant would outlive them. But better designs and improved surgical technique (including minimally invasive approaches) have made it possible to replace knees at younger and younger ages.

And consumers are stepping up to the plate so-to-speak by demanding knee replacements. This is especially true if they are active and want to remain active. They could also be responding to direct advertising aimed at knee pain sufferers who might not have thought of a joint replacement as the solution to the problem.

The authors conclude that the trends their study uncovered may be very significant. Health care policy makers must take into account the probability that the total number of knee replacements will continue to rise over the next 10 years. The health care system must prepare for this and be prepared for it! Other studies are needed to look for other factors and to see if racial minorities are included in this trend and if not, why not.

Reference: Elena Losina, PhD, et al. The Dramatic Increase in Total Knee Replacement Utilization Rates in the United States Cannot Be Fully Explained by Growth in Population Size and the Obesity Epidemic. In The Journal of Bone and Joint Surgery. February 1, 2012. Vol. 94A. No. 3. Pp. 201-207.

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