Chinese translation and validation of the Kujala scale for patients with patellofemoral pain

Purpose: This study translated and validated the Kujala scale, a well-documented questionnaire for patients with patellofemoral pain, into Chinese version. Method: Chinese Kujala scale was translated from the original English version following the recommendations of the International Society for Pharmacoeconomics and Outcomes Research. Sixty four Chinese reading patients who are diagnosed of patellofemoral pain were recruited from multiple hospitals and physiotherapy clinics. Psychometric property was evaluated in terms of test-retest reliability and internal consistency. Convergent validity was examined by Spearman rank correlation coefficient tests by comparing its score with the validated Chinese version of WOMAC Osteoarthritis Index and SF-36. Results: Chinese Kujala scale demonstrated excellent reliability (ICC = 0.968, p < 0.001). Cronbach's a of individual questions and its overall value were above 0.7. Strong correlation was found between the Chinese Kujala scale and the WOMAC Osteoarthritis Index (rho = -0.708, p < 0.001). Fairly weak correlations were also found between Chinese Kujala scale with the "physical" (rho = 0.413-0.498, p < 0.001) and "energy vitality" (rho = 0.290, p = 0.02) domains of SF-36. However, the relationship between the "bodily pain" was not significant (rho = 0.136, p = 0.284). Conclusion: The Chinese translated version of Kujala scale is a reliable and valid instrument for assessing the patellofemoral pain associated functional disturbances among the patient cohort.