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Measuring Change in Knee Function Before and After Treatment

In today's evidence-based medicine, patient satisfaction is important but so are measurable outcomes. Finding ways to quantify before and after change in terms of function is also important. In this study, physical therapists compare the reliability and responsiveness of three tools used to measure change in knee function. All patients (168 total) in the study had a diagnosis of knee osteoarthritis.

The three tools compared included the most widely used scale: the Western Ontario and McMaster Universities Osteoarthritis Index or WOMAC. The other two patient surveys were the Knee Outcome Survey (KOS) and the Lower Extremity Functional Scale (LEFS).

Each one of these self-report instruments measures function in slightly different ways. For example, the WOMAC looks at pain during activities, stiffness after prolonged positions, and ability to perform movements like standing up from a sitting position, dressing self, going up and down stairs, and walking. The KOS assesses limitations caused by pain, swelling, and joint instability. The LEFS looks more at the degree-of-difficulty someone has performing specific tasks during activities of daily living.

Everyone in the study completed all three surveys before and after treatment. Treatment consisted of a physical therapy program of leg strengthening, stretching, balance, and agility exercises. The exercise program took place twice a week for six to eight weeks. Patients were followed for up to one-year at regular intervals (two months, six months, 12 months).

The results showed that to measure change in knee function, all three tools are reliable and responsive. Therapists using these self-reported instruments may get slightly different information but all three surveys will reflect change and can therefore be used to obtain outcome measures. There was a trend observed with all three tools: the longer the follow-up, the less reliable the tools were to measure patients' responsiveness to treatment.

There may be some specific reasons for this trend. For example, as people improve there may be less change occurring making it more difficult to measure change with these particular questions. There may also be differences in patient osteoarthritis that contribute to reduced observations of change. For example, someone with acute arthritis versus someone with a chronic condition may not respond to treatment in the same way. More studies are needed to examine these factors more closely.

Valerie J. Williams, PT, DPT, MS, et al. Comparison of Reliability and Responsiveness of Patient-Reported Clinical Outcome Measures in Knee Osteoarthritis Rehabilitation. In Journal of Orthopaedic & Sports Physical Therapy. August 2012. Vol. 42. No. 8. Pp. 716-723.


*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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