Objective: To conduct a cross-cultural adaptation and determine the test-retest reliability of the Thai version of the Kujala Patellofemoral questionnaire (KPQ).
Material and Method: The present study comprised two phases: cross-cultural adaptation and test-retest reliability. The
KPQ was first translated and cross-culturally adapted from English to Thai. The content validity test was conducted, and the final version of the Thai version of Kujala Patellofemoral Questionnaire was developed. Forty knee pain patients were
enrolled in this study to determine test-retest reliability of the final version of this questionnaire. All 40 subjects were patients
from the Physical Therapy Center, Faculty of Physical Therapy, Mahidol University with a diagnosis of anterior knee pain by
physical therapists. They were asked to complete the questionnaires; the 1st session after registration and 2nd session 30 minutes after finishing the first administration. For statistical analysis, the intraclass correlation coefficient (ICC(2,1)) method was used to determine test-retest reliability.
Results: All 40 subjects (36 women, 4 men; with age range 18-56 years) were assessed twice with 30-minute time interval. Thirteen questions indicated strong reliability, ranging from ICC2,1 0.8 to 1.0 and the total score was ICC2,1 0.98.
Conclusion: The Thai version of the Kujala Patellofemoral Questionnaire was cross-culturally adapted, validated, and
presented with excellent test-retest reliability. Regarding clinical implication, this questionnaire is now available for Thai physical therapists in evaluating Thai knee pain patients.

Keywords: Patella, Patellofemoral pain syndrome, Questionnaires, Reliability