Autologous Osteochondral Transfer Demonstrates Satisfactory Clinical Outcomes and Durable Cartilage Properties: A Mean 4-Year Follow-up Using Quantitative MRI

Background: Autologous osteochondral transfer (AOT) is preferred because of its ability to replace defective cartilage with hyaline cartilage. However, longitudinal changes in hyaline cartilage after AOT and their correlation with clinical outcomes remain unclear. Purpose/Hypothesis: The purpose of the study was to evaluate the short- to midterm outcomes of AOT and to investigate the correlation between clinical outcomes and the morphologic and qualitative findings of cartilage. It was hypothesized that cartilage would remain stable over the follow-up period and that clinical outcomes would correlate with cartilage status. Study Design: Case series; Level of evidence, 4. Methods: Patients who underwent AOT between 2002 and 2021 and were followed for a minimum of 2 years were retrospectively reviewed. Clinical outcomes were assessed at postoperative early term (1-2 years postoperatively) and at the short- to midterm period (2-6 years postoperatively) using the Lysholm score, International Knee Documentation Committee (IKDC) score, Tegner activity scale, and visual analog scale (VAS) for pain. Morphology of cartilage was evaluated using MOCART (magnetic resonance observation of cartilage repair tissue) 2.0 scores, and quality was assessed using quantitative magnetic resonance imaging (MRI) T2 mapping. In those who were assessed with serial MRIs at early term and short-to-midterm intervals, correlation analysis was performed to assess the relationship between MRI and clinical outcomes. Results: A total of 45 patients with a mean age of 36.6±14.0 years (range, 16–63 years) were included. The mean follow-up period was 4.3±1.2 years. The mean MOCART score was 84.0±11.5 at early term and 78.1±21.0 at midterm, with no significant changes between follow-up intervals. T2 value also remained unchanged between postoperative follow-ups. Significant improvements in the Lysholm, IKDC, and VAS scores observed at the early term improved further through the midterm period. The MOCART score at the postoperative early term was correlated with VAS improvement ( P = .003); however, no significant correlation was found between other clinical and MRI outcomes. Conclusion: Postoperative improvements in clinical and MRI outcomes after AOT at the early term follow-up were maintained through a mean follow-up of 4 years. The further improvement in clinical outcomes, despite stable MRI findings, suggests a limited correlation between structural and clinical outcomes.