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

Purpose: 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. Methods: 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. Results: 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). Conclusion: 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.