Autologous Osteochondral Transplantation for Osteochondral Lesions of the Talus

Background: Autologous osteochondral transplantation (AOT) is used to treat osteochondral lesions (OCLs) of the talus, typically reserved for lesions greater than 150 mm₂. Few studies exist examining the functional and magnetic resonance imaging (MRI) outcomes following this procedure. The purpose of this study was to investigate functional and MRI outcomes, including quantitative T2 mapping following AOT. Methods: Eighty-five consecutive patients who underwent AOT were identified. Functional outcomes were assessed pre- and postoperatively using the Foot and Ankle Outcome Score (FAOS). The Magnetic Resonance Observation of Cartilage Repair Tissue (MOCART) score was used to assess cartilage incorporation. Quantitative T2 MRI relaxation time of graft tissue and adjacent normal cartilage values were recorded in a subset of 61 patients. The mean clinical follow-up was 47.2 months, with mean MRI follow-up of 24.8 months. Results: Mean FAOS improved pre- to postoperatively from 50 to 81 (P <.001). The mean MOCART score was 85.8. Lesion size was negatively correlated with MOCART score (r = -'0.36, P =.004). Superficial T2 values in graft tissue were higher than control tissue (42.0 vs 35.8, P <.001). Deep T2 values in graft tissue were similar to the control values (30.9 vs 30.0, P =.305). Functional outcomes were similar in patients irrespective of whether they had previous microfracture or concomitant procedures. Conclusion: AOT was an effective treatment for large OCLs of the talus in the current study. MOCART scoring indicated good structural integrity of the graft. Quantitative T2 mapping suggests that graft tissue may not always mirror native hyaline cartilage. The long-term implications of this are not yet known. Level of Evidence: Level IV, case series.