Validity and reliability of Thai version of the International Knee Documentation Committee Subjective Knee Form

Self-administered questionnaires have become an important aspect for clinical outcome assessment of knee-related surgery. The International Knee Documentation Committee (IKDC) Subjective Knee Form is a knee-specific questionnaire that is widely used and translated to many languages. The purposes of the present study were: (1) to translate the questionnaire into Thai; and (2) to assess the validity and reliability of the Thai version of the International Knee Documentation Committee (IKDC) Subjective Knee Form.

The IKDC Subjective Knee Form was translated into Thai using forward-backward translation protocol. Afterward, reliability and validity were tested The responses of 55 consecutive patients on two questionnaires, the Thai IKDC Subjective Knee Form and the Short Form-36, were used. The validity was tested by correlating the scores from both questionnaires. The reliability was adopted by measuring the test-retest reliability and internal consistency.

The Thai IKDC Subjective Knee Form showed good correlations with the physical functioning and bodily pain domains of the SF-36 (Pearson's correlation coefficient = 0.75 and 0.76 respectively). The reliability proved excellent with an intra-class correlation coefficient of 0.92 for test-retest. The internal consistency was strong (Cronbach alpha = 0.92).

The Thai version of IKDC Subjective Knee Form showed good value to retain the characteristic of the original version. In addition, it was a reliable evaluation instrument for patients with knee-related problems.