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Rheumatology (Oxford). 2009 Feb;48(2):160-4. doi: 10.1093/rheumatology/ken439. Epub 2008 Dec 23.

Can patients help with long-term total knee arthroplasty surveillance? Comparison of the American Knee Society Score self-report and surgeon assessment.

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Department of Orthopaedic Surgery, University of Minnesota Medical School, Department of Veterans Affairs Medical Center, Section 112E, 1 Veterans Drive, Minneapolis, MN 55417, USA.



To compare patient self-report of knee flexion, extension, range of motion (ROM) and American Knee Society (AKS) Pain, Knee and Functional scores with a clinician assessment.


A total of 239 consecutive total knee arthroplasty (TKA) patients (290 knees) were mailed surveys with an AKS questionnaire and lateral knee photographs that showed knee ROM in 10 degrees increments to compare their operated knee(s) ROM. Patients were subsequently seen in clinic and their ROM, AKS Pain, Knee and Functional scores were measured. Patient- and physician-reported measures were compared using independent sample t-test and correlated using Spearman's correlation coefficient. A priori rules for comparisons were based on previously published reports.


A total of 286 knees had both survey and clinic data available and constituted the analytic set. Patient-reported and physician-assessed extension, flexion and ROM were: 3 +/- 4.8 degrees vs 1.4 +/- 4.3 degrees (P < 0.001), 111.4 +/- 14.6 degrees vs 110 +/- 12.8 degrees (P = 0.04) and 108.6 +/- 16.8 vs 108.6 +/- 14.3 degrees (P = 0.98). There was a moderate correlation between patient and physician assessments (extension = 0.31; flexion = 0.44; ROM = 0.42; P < or = 0.001 for all). Patient-reported and physician-assessed AKS Pain, Knee and Functional scores were: 35.8 +/- 15.6 vs 43.9 +/- 11.1 (P < 0.001), 79.8 +/- 20 vs 88.9 +/- 13.3 (P < 0.001) and 57.7 +/- 23.1 vs 65.7 +/- 26.4 (P < 0.001), respectively. Patient- and physician-assessed AKS Pain, Knee and Functional scores had moderate-high correlation (r = 0.49, 0.49 and 0.70; P < or = 0.001 for all).


Long-term surveillance of TKA patients may be possible using a self-report AKS, but the average 8- to 10-point difference between patient- and physician-reported AKS scores (patients reporting poorer scores) represents a substantial impact on this outcome instrument. Since patient-reported responses have clear value in global assessment, further evaluation with other validated outcome instruments is warranted.

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