Abstract
Background:
Recently a new version of the Knee Society Knee Scoring System has been developed, adapted to the lifestyle and activities of contemporary patients with a Total Knee Arthroplasty (TKA). It is subdivided into 4 domains including an Objective Knee Score, a Satisfaction Score, an Expectations Score and a Functional Activity Score. Before this scale can be used in non-English speaking populations, it has to be translated and validated for specific populations. The aim of this study was to translate and validate the New Knee Society Knee Scoring System (new KSS) for Dutch speaking populations.
Materials and Methods:
A Dutch translation of the New KSS was established using a forward-backward translation protocol. 137 patients undergoing TKA were asked to complete the Dutch translation of the New KSS as well as the Dutch WOMAC, Dutch KOOS and the Dutch SF12. To determine the test-retest reliability, 53 patients were asked to fill out a second questionnaire with one-week interval. We tested the test-retest reliability of the subjective domains of the New KSS by assessing the intra-class coefficient and the Pearson correlation coefficient between the first and second questionnaires. Systematic differences between the first and second questionnaires were investigated with T-tests and non-parametric statistics. Internal consistency of the Dutch new KSS was evaluated with Cronbach's alpha. The construct validity of the Dutch New KSS was determined by comparing it to the Dutch WOMAC, Dutch KOOS and Dutch SF12 using Pearson correlation coefficients. Content validity was assessed by examining the distribution and the floor and ceiling effects of the Dutch version of the new KSS.
Results:
The reliability of the Dutch translation of the New KSS proved excellent with an ICC ranging from 0.75 to 0.92 for single measures and from 0.85 to 0.96 for average measures in the different domains. Cronbach's alpha ranged from 0.86 to 0.96 indicating good to excellent internal consistency. Paired t-tests and non-parametric statistics revealed no significant differences between the first and second questionnaires while paired samples correlations were highly significant (p < 0.001). The Dutch New KSS correlated well with the Dutch WOMAC score (r = 0.81; p < 0.001), the Dutch KOOS (r = 0.77; p < 0.001), and the Dutch SF12 (r = 0.62; p < 0.001). Content validity was good with a normal distribution of the calculated scores and absence of floor or ceiling effects.
Conclusions:
The validation procedure demonstrated that the proposed Dutch version of the New Knee Society Knee Scoring System is a reliable and valid instrument for evaluating symptoms, function, expectations and satisfaction after TKA in Dutch speaking patients.
