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Knee News

Putting Knee Replacement Results to the Test

Would you have a knee replacement if it wasn't going to make you feel better? Not likely! How do doctors know if replacing a knee joint is the answer for severe arthritis? They do tests. Patients and insurance companies want real evidence to show that treatments are effective. Health care workers are looking at all the tests available that measure patients' results. Each health problem is different and may need a different test to measure results.

No matter what tests are used, research requires that they are valid and reliable. "Valid" means a test is a true measure of the thing in question. "Reliable" means the results can be trusted. If the test is given a second time, the results should be the same. In the case of health care issues, a third part is necessary. This is the before-and-after measure, or a measure of change over time. Researchers call this "responsiveness."

Measuring responsiveness is a fairly new part of the picture. There aren't very many studies to show health care workers which tests work the best to measure responsiveness. A group of scientists in Canada set out to identify these tests. They studied patients who had total knee replacement for arthritis. Tests were done before surgery, after surgery, and during the entire study period (beginning to end).

Two areas were studied: patients' function and quality of life. "Function" is what a person can do physically. In this case, walking and climbing stairs were used as measures of improvement or responsiveness. "Quality of life" includes how satisfied the patient is before and after surgery. Other quality of life measures include amount of pain or ability to sleep at night.

The researchers found that different tests were better measures of change at different points in the process. Some were better measures of function or quality of life before surgery. Others registered small changes right after surgery. Still other tests were better when used from start to finish.

For example, stair climbing turned out to be too difficult for some patients to do even two months after surgery. Walking was also hard--and so not the best measure of change. Easier activities of daily living were better measures of the rapid changes that can happen after total knee replacement.

Tests that measure small but important changes soon after total knee replacement have been identified. These tools can be used by doctors and physical therapists to show patient responsiveness during the first few months after surgery. Quality of life is also accepted as a valid measure of improvement since this is what is important to patients. Knowing what kinds of changes to expect after surgery can help doctors and patients to plan treatment.


Eric Parent, MSc, and Helene Moffet, PhD. Comparative Responsiveness of Locomotor Tests and Questionnaires Used To Follow Early Recovery After Total Knee Arthroplasty. In Archives of Physical Medicine and Rehabilitation. January 2002. Vol. 83. No. 1. Pp. 70-80.

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*Disclaimer:* The information contained herein is compiled from a variety of sources. It may not be complete or timely. It does not cover all diseases, physical conditions, ailments or treatments. The information should NOT be used in place of visit with your healthcare provider, nor should you disregard the advice of your health care provider because of any information you read in this topic.
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