To aggravate matters, arthritis is also prevalent among the overweight - which describes nearly 65% of our nation's adult population. Fortunately, treating the pain and disability of arthritis has been revolutionized by surgical joint replacements of the hips and knees.

Unfortunately, as hip and knee replacements have become a more popular option, the toll on Medicare, private insurers and hospitals has escalated. Despite its huge implications for the health care system, the projected impact of joint replacements has attracted scant study.

To assess and address this issue, Sunny Kim, PhD, a researcher with the Robert Stempel School of Public Health at Florida International University, started with one of the largest databases of hospital procedures available: the Nationwide Inpatient Sample (NIS).

Using the latest revision of international procedure coding, Kim identified joint replacement cases throughout the US and analyzed increases in surgeries and costs between 1997 and 2004.

The April 2008 issue of Arthritis Care & Research presents hard-hitting numbers to back her conclusion: "the burden resulting from hip/knee joint replacement is not only substantial but also increasing at a steep rate."

Among Kim's significant, distressing findings:

• In 2004, approximately 431,485 primary knee replacements were performed—a 53% increase from the year 2000. 225,900 primary hip replacements were performed in the US—marking a 37% increase for the same period.

• In 1997, about 60% of primary hip replacements and 69% of primary knee replacements were performed on individuals between the ages of 65 and 84 years. Although elderly patients remained the main recipients, the number of joint replacement surgeries among the middle-aged, patients between 45 and 64 years, increased excessively—71% for hip replacements and 83% for knee replacements—in 2004.

• Between 1997 and 2004, the hospital charges for joint replacements, both primary and revision surgeries, increased faster than the rate of inflation. While Medicare continued to provide the principal source of payment, compared with other sources of payment, the relative burden decreased. The burden on private insurance more than tripled in that 7-year span—from $1.1 billion to $3 billion for hip replacements and from $1.46 billion to $4.64 billion for knee replacements.

• If current trends persist, nearly 600,000 hip replacements and 1.4 million knee replacements will be performed in the year 2015.

Reflecting on the rise in the numbers of joint replacements and in surgeries among younger patients, Kim raises decreased lack of tolerance for pain and increased acceptance of surgical safety, as well as the impact of obesity, as possible explanations. She also acknowledges the study's inability to track the rates and costs of a less-invasive surgery for hip and knee replacements, performed on an outpatient basis for selected patients.

Calling for the creation of a national joint replacement registry as one key step, Kim stresses the need for urgent attention to the problems that come with the territory of this popular, radical arthritis treatment. "Public health education is critically important to reduce the proportion of people who are overweight as well as to manage arthritis at earlier stages," she notes. "At the same time, given the steeply increasing trends of joint replacements and the expected number of joint revisions needed, the health care community should be prepared for this upcoming demand of surgical loads and its economic burden on government and private insurance systems."

[Source: Wagner S. Wiley-Blackwell]