Study design: Clinical measurement.
Objective: To translate and culturally adapt the International Knee Documentation Committee (IKDC) Subjective Knee Form into Turkish and to determine selected psychometric properties of the translated version.
Background: The IKDC Subjective Knee Form is widely used to evaluate disability associated with knee injuries, but it has not yet been translated or culturally adapted for Turkish-speaking individuals.
Methods: The IKDC Subjective Knee Form was translated into Turkish, consistent with published methodological guidelines. The process included 2 forward translations, followed by the synthesis of these translations, and 2 backward translations, followed by an analysis of the translations and creation of the final version. The measurement properties of the Turkish IKDC Subjective Knee Form (internal consistency, construct validity, and floor and ceiling effects) were tested in 103 patients (52 male; average ± SD age, 34.9 ± 11.9 years) with a variety of knee pathologies. Reproducibility was tested in 58 patients (28 male; age, 33.7 ± 10.6 years) over 3 to 14 days, and responsiveness was tested in 33 patients (23 male; age, 30.8 ± 8.0 years) with anterior cruciate ligament reconstruction. Cronbach alpha was used to assess internal consistency, and intraclass correlation coefficients were used to estimate the test-retest reliability. Construct validity was analyzed with the Turkish version of the Lysholm knee score, the Kujala Anterior Knee Pain Scale, and the Medical Outcomes Study 36-Item Short-Form Health Survey.
Results: The Turkish version of the IKDC Subjective Knee Form showed excellent internal consistency (Cronbach coefficient α = .89) and test-retest reliability (intraclass correlation coefficient = 0.91). The correlation coefficients between the IKDC Subjective Knee Form and the Lysholm knee score and Kujala Anterior Knee Pain Scale were 0.64 and 0.89, respectively (P<.001). The highest correlations between the IKDC Subjective Knee Form and the Medical Outcomes Study 36-Item Short-Form Health Survey were observed in the physical functioning subscale and the physical component summary score (r = 0.69 and r = 0.70, respectively; P<.05); the lowest correlations were observed in the mental health subscale and mental component summary score (r = 0.13 and r = 0.05, respectively). We observed no floor or ceiling effects. The IKDC Subjective Knee Form demonstrated a large effect size with the group tested (2.09; 95% confidence interval: 1.61, 2.59).
Conclusion: The Turkish version of the IKDC Subjective Knee Form has sufficient reliability and validity to measure patient-reported outcomes for Turkish-speaking individuals with a variety of knee disorders.
Keywords: ACL; IKDC; reliability; validity.