JANUARY 15, 2004

Active baby boomers consider knee and hip replacements... well, hip

Those under 55 are replacing joints at an unprecedented rate.
Will they outlive their artificial parts?

NIH confirms effectiveness of total knee replacement, but more study is needed

More than 20 years of research show that, for most people suffering from severe knee pain and disability that doesn't respond to nonsurgical therapies, total knee replacement (TKR) is a safe, cost-effective treatment for restoring physical function and mobility and relieving discomfort.

Despite advances in TKR technology since its first use in the late 1950s, questions remain about which materials, implant designs and surgical approach give the best outcome for specific patient groups. Surgical technique, choice of prosthesis as well as volume of procedures performed by the surgeon and hospital affect both short- and long-term success. Skill appears to increase the more the technique is done. Other factors that contribute to positive outcomes are pre- and postoperative risk assessment, antibiotic prophylaxis, pain management and treatment of medical conditions.

While knee prostheses are generally durable, revisions are sometimes necessary, especially due to loosening of the prosthesis. Patient risk factors include age younger than 55, male gender, diagnosis of osteoarthritis, obesity and presence of comorbid conditions.

Clear evidence exists for racial, ethnic and gender differences in the provision of TKR, but the reasons aren't well understood. Patients' mistrust of the healthcare system and lack of familiarity with the procedure, and physicians' beliefs about patients may each play a role. These are among the findings of a recent consensus report. The final version of the panel's statement will be available at www.consensus.nih.gov.


When her doctor saw the condition of Janet Wright-Smit's joints he didn't hesitate to recommend a knee replacement. The operation on one knee was done last March. A second is scheduled for early this month.

It was "pretty traumatic," says Ms Wright-Smit, but she would "strongly encourage someone to face and embrace" joint replacement surgery. At age 57, she is one of a growing number of baby boomers getting new hips and knees at an earlier age than their parents did.

Although 70% of these procedures in Canada are performed on people 65 years of age and older, the 45-54 age group experienced an increase of 90% for knee and 30% for hip replacement, according to a report on joint replacement compiled using information from the Canadian Joint Replacement Registry (CJRR) that was released by the Canadian Institute for Health Information (CIHI).

The risk of surgery was worth taking for nurse Wright-Smit, who lives in Guelph, Ont. She lived an active life until seven years ago when arthritis and chronic fatigue syndrome forced her to stop working as a nurse and eventually landed her in a wheelchair. One knee was replaced last April and she expects the second to be done this month.

Liberating operation
"It is amazing how liberating this is and I feel grateful and blessed to live in Canada," she says. Osteoarthritis runs in her family. She recalls that her grandmother could do little more than move between her bed and rocking chair and kept a bottle of what her grandchildren were told was lemon juice at her side. It was actually alcohol, the only way she had of coping with the pain.

"Total hip and knee replacements traditionally have depended on a metal-plastic articulation which wears and creates minute particles which stimulate bone resorption," says Dr Robert Bourne, an orthopedic surgeon at the London Health Sciences Centre in London, Ont and Chair of the CJRR advisory. This is particularly worrisome in young, active patients, but there are many new technologies emerging that look promising to keep younger patients on the ski hills and golf courses.

"These include ceramics, metal-on-metal, oxidized zirconium metal and cross-linked polyethylenes, which seem promising in allowing total joint replacements in younger people," Dr Bourne says. He also points out that few long-term studies are available, and the CJRR will gather more data to help health professionals know which patients do best, which surgical techniques work best and which implants provide the most durable results, requiring less revision. It will also keep track of the waiting period and the impact this has on the results of surgery.

Sweden is leading the way in collecting data, with a joint registry that was started in the 1970s. At that time, revision rates were about what they are today in North America, but now the Swedish revision rates have been cut in half.

Revision surgery
The cost of hip or knee replacement is about $10,000 and the revision is a more difficult surgery.

"The results are not as good as after a first-time knee replacement," says Dr Nazir Mohamed, an orthopedic surgeon at the Toronto Western Hospital and Chair of the Research Committee for the Ontario Joint Replacement Registry. "There is the potential at some point that the joint may not be reconstructable, therefore in very young individuals we try to defer doing joint replacement surgery until they are older so that the number of revisions they may require in their lifetime is no more than one or two."

The age group getting joint replacement surgery will get younger as technology, information and experience with implants increases, according to the doctor. Joint replacements are expected to double over the next two decades as the population ages.



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