Evaluation of reproducibility of the MOCART score in patients with osteochondral lesions of the talus repaired using the autologous matrix-induced chondrogenesis technique

To evaluate the applicability and reproducibility of magnetic resonance observation of cartilage repair tissue (MOCART) score for morphological evaluation of osteochondral lesions of the talus (OLT) repaired using autologous matrix-induced chondrogenesis (AMIC) technique. Two radiologists (R1-R2) and two orthopaedists (O1-O2) independently reviewed 26 ankle MRIs performed on 13 patients (6 females; age: 38.9 +/- 15.9, 14-63) with OLT repaired using AMIC. The MRIs were performed at 6 and 12 months from surgery. For inter/intra-observer agreement evaluation for each variable of the MOCART, we used Cohen's kappa coefficient. Progression of MOCART between 6- and 12-month evaluation was assessed using the Wilcoxon test. The Spearman's correlation coefficient was used to evaluate the correlation between baseline lesion size and MOCART. The inter-observer agreement between R1 and R2 ranged from poor (adhesions, k = 0.124) to almost perfect (subchondral bone, k = 0.866), between O1 and O2 from absent (effusion, k = -0.190) to poor (surface, k = 0.172), and between R1 and O1 from absent (cartilage interface, k = -0.324) to fair (signal intensity, k = 0.372). The intra-observer agreement of R1 ranged from poor (signal intensity, k = 0.031) to substantial (subchondral lamina, k = 0.677), while that of O1 from absent (subchondral bone, k = -0.061) to substantial (surface, k = 0.663). There was a significant increase of MOCART between 6- and 12-month evaluation of R1 (Z = -2.672; P = 0.008), R2 (Z = -2.721; P = 0.007) and O1 (Z = -3.034; P = 0.002). Conversely, the increase of MOCART of O2 was not significant (Z = -1.665; P = 0.096). Inverse correlation between lesion size at baseline and MOCART was significant at 12-month evaluation (-0.726; P = 0.005). MRI has an important role in the follow-up of surgical repaired OLT, but MOCART score does not seem to be sufficiently reproducible to be applied for this purpose.