The 12-item Oxford Knee Score: cross-cultural adaptation into German and assessment of its psychometric properties in patients with osteoarthritis of the knee.
OBJECTIVE
To cross-culturally adapt and validate the Oxford Knee Score (OKS) for use in German-speaking patients with osteoarthritis of the knee.


METHODS
After the cross-cultural adaptation (OKS-D), the following metric properties of the questionnaire were assessed in 100 consecutive patients (mean age 66.5 years, 61 women) undergoing total knee replacement: feasibility (percentage of fully completed questionnaires), reliability (Intraclass Correlation Coefficients [ICC] and Bland and Altman's limits of agreement), and construct validity (correlation with the Western Ontario and McMaster Universities Index [WOMAC], Knee Society Score [KSS], Activities of Daily Living Scale [ADLS], and Short Form 12 [SF-12]), floor and ceiling effects, and internal consistency (Cronbach's Alpha, CA).


RESULTS
We received 91.9% fully completed questionnaires. Reliability of the OKS-D was excellent (ICC 0.91). Bland and Altman's limits of agreement revealed no significant bias (-0.2) and a random error of 6.2. Correlation coefficients with the other questionnaires ranged from -0.22 (SF-12 Mental Component Scale [MCS]) to -0.77 (ADLS). We observed no floor or ceiling effects. The CA was 0.83.


CONCLUSIONS
The German version of the OKS is a reliable and valid measure for the self-assessment of pain and function in German-speaking patients with osteoarthritis of the knee.
Naal
F D
FD
Department of Orthopaedic Surgery, Schulthess Clinic, Zurich, Switzerland. florian.naal@gmail.com
Impellizzeri
F M
FM
Sieverding
M
M
Loibl
M
M
von Knoch
F
F
Mannion
A F
AF
Leunig
M
M
Munzinger
U
U
D000368:Aged; D000369:Aged, 80 and over; D003431:Cross-Cultural Comparison; D005260:Female; D005858:Germany; D006801:Humans; D007719:Knee Joint / Q000503:physiopathology; D007802:Language; D008297:Male; D008875:Middle Aged; D020370:Osteoarthritis, Knee / Q000175:diagnosis* / Q000503:physiopathology; D010147:Pain Measurement / Q000379:methods; D011594:Psychometrics; D015203:Reproducibility of Results; D012720:Severity of Illness Index