Abstract
PURPOSE: The use of patient-reported outcome measures (PROMS) is the cornerstone of clinical research for surgical disciplines, but the use in daily routine can be challenging. One of the most widespread PROMS in knee surgery is the International Knee Documentation Committee (IKDC) questionnaire. The purpose of the present study was to investigate the potential correlation of the IKDC score with a patient's subjective assessment of the knee using a single question. We hypothesized a correlation between the IKDC score and single question score. METHODS: A prospective, single center study in a comprehensive knee outpatient clinic was performed. Patients willing to participate, presenting in the clinic for the first time were asked to complete the IKDC questionnaire and to answer the question: "How does your knee know compare to when you were 16 years old, in percentage?" Pearson correlation coefficient and linear regression were used to analyze the IKDC score and the single-question percentage. RESULTS: After application of inclusion and exclusion criteria, 310 patients were included. The mean age of the participants was 43.3 ± 9.6 years, and 45.2% of the patients were female. Mean IKDC score was 41.11 ± 13.13, compared to the mean score of the single-question 40.90 ± 22.7 (p = 0.887). The correlation between the IKDC score and the single-question was significant (p < 0.001), however, the person coefficient was 0.460, indicating moderate correlation. The linear regression analysis was also statistically significant (p < 0.001), but with a model fitness of r(2) = 0.211 and B = 0.266. From the 310 patients, 305 (98.4%) found the single-question of more relevance than the IKDC score. CONCLUSION: IKDC score and a simple, subjective, knee self-evaluation using a single question demonstrate moderate correlation. The single question can be used for better understanding of discrepancy between the objective score and the patients' subjective perception of knee function or as a fast, single question proxy score.