Validation and reliability of the Kujala Scale for Chinese population with patellofemoral disorders

Background and Purpose: Patellofemoral disorders are common orthopaedic conditions in active adults. However, a validated instrument for outcome measurement in Chinese population was lacking. This study translated and validated the Kujala scale, a well documented questionnaire for this patient group, into Chinese version. Methods: Following the recommendations of the International Society for Pharmacoeconomics and Outcomes Research, Chinese Kujala scale was translated from the original English version. Sixty four Chinese reading patients with medical diagnosis of patellofemoral pain were recruited from multiple hospitals and physiotherapy clinics. The psychometric property of the translated instrument was examined in terms of testeretest reliability and internal consistency. Convergent validity was evaluated by Spearman rank correlation coefficient (rho) tests by comparing its score with the validated Chinese version of WOMAC Osteoarthritis Index and SF-36. Results: Chinese Kujala scale demonstrated excellent test-retest reliability (ICCZ0.968). The overall Cronbach alpha and the values of individual questions were above 0.7. Strong correlation was found between the Chinese Kujala scale and the WOMAC Osteoarthritis Index (rhoZ-0.708, p<0.001). Weak correlations were found between Chinese Kujala scale with the physical domains of SF-36 (rhoZ0.413 to 0.498, p<0.001). Likewise, weak correlation was also noticed between the “energy vitality” domain (rhoZ0.290, pZ0.02) but the association between the “bodily pain” was not significant (rhoZ0.136, pZ0.284). Conclusion: The Chinese translated version of Kujala scale is a reliable and valid instrument for patients with patellofemoral disorders. The current findings are believed to promote multinational investigations in this patient group.