Total Knee Arthroplasty Relieves Functional Limitations in Older Patients

By Todd Neale
DURHAM, N.C., 20 oct 2008-- For older patients with osteoarthritis, total knee arthroplasty was associated with improved physical functioning, researchers here found.
Medicare recipients who underwent the procedure showed significant improvements in three levels of physical functioning, whereas those who did not have total knee replacement worsened, Linda George, Ph.D., of Duke University, and colleagues reported in the October issue of Arthritis & Rheumatism.
Procedures like joint replacement are likely contributing to the decreasing rates of disability in the older population, the researchers said.
It has been well established that total knee arthroplasty is safe for older patients and improves joint-specific outcomes like pain and range of motion, they said, but few studies have examined whether the procedure also has benefits for higher-level physical functioning.
To explore the issue, Dr. George and colleagues obtained data from the Medicare Current Beneficiary Survey Cost and Use files on older patients who had been diagnosed with osteoarthritis of the knee.
The researchers identified 259 patients who had undergone unilateral total knee arthroplasty from 1992 through 2003 and 1,816 who had not.
Physical functioning was self-reported at baseline and at least 80 days post-surgery. It was assessed on the basis of the difficulty in performing various tasks on three scales:
Nagi Disability Scale -- stooping/crouching, walking two to three blocks, and lifting objects weighing up to 10 pounds
Instrumental Activities of Daily Living Scale -- performing light housework, performing heavy housework, preparing meals, and personal shopping
Activities of Daily Living Scale -- bathing/showering, getting dressed, getting in and out of a chair, walking, and using the toilet
The average intervals between the baseline and follow-up interviews were 13 months for patients who had had the procedure and 16 months for those who had not.
At baseline, the group that received treatment was significantly more impaired.
Compared with the group that did not receive total knee arthroplasty, the treatment group was significantly better at follow-up on nine of the 12 total physical tasks evaluated (P<0.05 for all) -- all but performing heavy housework, getting in and out of a chair, and getting dressed.
Within the treatment group, individuals showed significant improvement from baseline on 10 of the 12 tasks (P<0.05), excluding getting dressed and getting in and out of a chair.
The average treatment effects were significant for two of three tasks on the Nagi Disability Scale (lifting and walking), three of four tasks on the Instrumental Activities of Daily Living Scale (light and heavy housework, and shopping), and one of five tasks on the Activities of Daily Living Scale (bathing) (P≤0.05 for all).
"It is not surprising that improvements in Nagi Disability Scale activities and Instrumental Activities of Daily Living Scale tasks were more common than those for Activities of Daily Living Scale tasks because the latter represent very basic indicators of physical functioning," the researchers said.
"If an individual is disabled in one or more Activities of Daily Living Scale tasks," they continued, "the odds of recovery of function are especially low."
Those who did not receive treatment significantly worsened on five of the 12 tasks (P<0.05 for all), and did not improve on any.
The authors acknowledged some limitations of the study, including the low number of patients who underwent total knee arthroplasty, the between-group difference in the length of the interval from baseline to follow-up, the use of propensity scores, and the use of patient self-report.
The study was supported by a grant from the Institute for Health Technology Studies.
The authors made no disclosures.
Primary source: Arthritis and RheumatismSource reference:George L, et al "The effects of total knee arthroplasty