Minimal Clinically Important Difference in Patients with Knee Cartilage Lesions Treated with a Cell-Free Scaffold Implantation

Objective: The aim of this study was to establish the minimal clinically important difference (MCID) thresholds for the International Knee Documentation Committee (IKDC) subjective and Visual Analogue Scale (VAS) pain scores in patients affected by knee chondral and osteochondral lesions treated with cell-free scaffold implantation. Design: For the MCID definition, 186 patients who underwent an osteochondral scaffold implantation were included. Patients were evaluated through the IKDC subjective and VAS pain scores at baseline, 12 and 24 months. The MCID was calculated using a distribution-based method for both IKDC subjective and VAS pain scores at 12 and 24 months, as well as with an anchor-based method. Results: The MCID values were 10.1 and 1.5 for the IKDC subjective and VAS pain scores, respectively, both at 12 and 24 months of follow-up. The rate of patients who achieved the MCID was 83% at 12 months and 88% at 24 months. The anchor-based method led to higher MCID values. Factors identified to increase the probability to reach the MCID were younger age (P = 0.042), male sex (P = 0.042), and lateral femoral condyle lesions (P = 0.002), while patellar lesions were less likely to reach the MCID (P = 0.009). Conclusions: This study defined the MCID values for the IKDC subjective and VAS pain scores after treatment with a cell-free biomimetic scaffold, with 88% of the patients achieving clinically relevant results at 2 years. Younger patients, males and lateral femoral condyle lesions were more likely to reach the MCID. However, the identified thresholds can be influenced by the method chosen, which warrants caution when interpreting study results.