Psychometrical properties of the Turkish translation of the New Knee Society Scoring System

OBJECTIVE: To translate the New Knee Society Scoring System (KSS) into Turkish and to evaluate the psychometric properties of the translated questionnaire. METHODS: This study was conducted on 66 knees of 43 pre-op patients who were scheduled for total knee arthroplasty (TKA) and 50 knees of 26 knee arthroplasty patients at least 6 months postoperatively. KSS was translated and culturally adapted according to the guidelines of Guillemin and Beaton. Demographic and clinical characteristics of the patients were recorded. Patients completed WOMAC, KOOS and SF-36 surveys along with the Turkish version of the new KSS. After the initial evaluation, patients were asked to refill the new KSS 1 week later. Internal consistency and reliability were tested using Cronbach's alpha coefficient and intraclass correlation coefficient (ICC). Validity was assessed by calculating the Spearman's correlation coefficient between the new KSS and WOMAC, KOOS and SF-36 scores. RESULTS: The mean ages of the pre and post-operative groups were 67.16 ± 7.85 years and 71.65 ± 6.95 years respectively. The Cronbach's alpha coefficients of the new KSS calculated for symptoms (0.814), patient satisfaction (0.947), patient expectations (pre-op = 1.000, post-op = 0.997) and functional activities (0.864) were high. The ICC scores ranged between 0.790 and 0.951. The pain subscore of the new KSS and the pain subscores of the WOMAC (r = −0.720; p < 0.01), KOOS (r = 0.550; p < 0.01) and SF-36 (r = −0.434; p < 0.01) were highly correlated. Emotional role functioning (RH), mental health (MH) and social role functioning (SF) subscores of SF-36 showed no correlation with the all subscores of the new KSS (p > 0.05). No floor or ceiling effects in the new KSS scores were detected. CONCLUSION: It is concluded that the new KSS is a valid and reliable questionnaire which can be used in evaluating the pre and post-operative Turkish speaking TKA patients. LEVEL OF EVIDENCE: Level III Diagnostic Study.