Development of a German version of the knee outcome survey for daily activities

The knee outcome survey-activities of daily living scale (KOS-ADLS) is a patient-reported specific measure of knee function. The KOS-ADLS includes items related to both symptoms and functional limitations experienced during ADL. The purpose of this study was to examine the reliability and validity of a cross-culturally adapted German version of the KOS-ADLS.

108 consecutive knee patients (n = 57 males/51 females) scheduled for outpatient physical therapy at an orthopedic hospital were enrolled in the investigation. For the reliability analysis, 50 patients were asked to complete the questionnaire on two non-consecutive days. To assess the validity of the KOS-ADLS, 58 additional patients answered the questionnaire in addition to performing a series of other related tests: (1) visual analogue scale for knee pain intensity, (2) The Get-up-and Go, and (3) time for ascending/descending stairs. The functional tests were selected because they directly related to specific items in the questionnaire and were thought to reflect the major areas of disability for this patient group.

The reliability analysis demonstrated that the German version of the KOS-ADLS had a good reliability (ICC range 0.94-0.97) and internal consistency (alpha 0.89). The functional tests (e.g. Get-up and Go, ascending/descending stairs) showed moderate correlations, whereas the visual analogue pain scale was highly correlated with the subscores and total score of the KOS-ADLS.

The psychometric characteristics of the German version of the KOS-ADLS produced reliable and valid results, as the original version, in detection of an individual's symptom and function related knee joint impairment.