Magnetic resonance observation of cartilage repair tissue (MOCART) 2.0 for the evaluation of retropatellar autologous chondrocyte transplantation and correlation to clinical outcome.

ABSTRACT

BACKGROUND: Matrix-associated chondrocyte transplantation (MACT) has become an established treatment option for cartilage defects. OBJECTIVE: Three objectives were defined first, to evaluate retropatellar cartilage grafts using Magnetic Resonance Observation of Cartilage Repair Tissue (MOCART) 2.0 score; second, to determine whether clinical outcome correlates with specific parameters or overall results; third, to screen those parameters for their ability to predict a clinical outcome of Delta IKDC ≥ 20 as a threshold for good clinical response at 12 months. METHODS: 38 patients were included of whom all underwent retropatellar MACT. MRI was performed 3, 6 and 12 months postoperatively. The clinical status was determined using International Knee Documentation Committee Subjective Form (IKDC). Correlations of MOCART 2.0 parameters and Delta IKDC scores were quantified by nonparametric Spearman's R. Those parameters with significant correlations (p < 0.05) were screened for their ability to predict a clinical outcome of Delta IKDC ≥ 20 at 12 months. RESULTS: Significant correlations were identified for the parameters MOCART total 6 months (p < 0.05), Surface 6 months (p < 0.05), Surface 12 months (p < 0.05), Structure 6 months (p < 0.01), Structure 12 months (p < 0.05), Subchondral changes 3 months (p < 0.0001), Subchondral changes 6 months (p < 0.05) and Subchondral changes 12 months (p < 0.05). Among all MRI score parameters, Subchondral changes 3 months achieved the highest accuracy of 0.76 (0.62-0.86) in predicting Delta IKDC ≥ 20 after 12 months. CONCLUSION: Some of the MOCART 2.0 parameters show significant correlation with Delta IKDC scores in the postoperative course after retropatellar MACT, which seems to depend on the time interval between surgery and MRI acquisition.