Persian translation and validation of the Kujala Patellofemoral Scale in patients with patellofemoral pain syndrome

Abstract

Purpose: To culturally translate and validate the Persian version of Kujala Patellofemoral Scale (KPS) and evaluate the test-retest reliability, internal consistency, construct validity and ceiling or floor effects of this instrument in patients with patellofemoral pain syndrome (PFPS). Method: After standard forward and backward translations, 100 patients with PFPS completed the Persian versions of the KPS and Short-Form 36 Health Survey (SF-36) in the first visit. With time interval of 23 days after the first visit, 47 patients filled out the KPS in the second visit. Test-retest reliability and internal consistency were assessed using intraclass correlation coefficient (ICC2,1) with 95% confidence interval (95% CI) and Cronbach's α coefficient, respectively. The Spearman's rank correlation (rs) was used to assess the correlations between the Persian KPS and SF-36 subscales. Results: The acceptable level of ICC >0.70 (ICC = 0.96, 95% CI = 0.930.98) and Cronbach's α coefficient >0.70 (α = 0.81) was obtained for the Persian KPS. There were low to moderate correlations (rs = 0.250.60, p