Relationship Between Bone Marrow Lesions on MRI and Cartilage Degeneration in Osteochondral Lesions of the Talar Dome

Background: In the evaluation of osteochondral lesions of the talar dome (OLT), bone marrow lesions (BML) are commonly observed in the subchondral bone on magnetic resonance imaging (MRI). However, the significance of BML, such as the histology of the overlying cartilage, is still unclear. The purpose of this study was to investigate the relationship between the BML and cartilage degeneration in OLT. Methods: Thirty-three ankles with OLT were included in this study. All ankles underwent CT and MRI and had operative treatment. The ankles were divided into 2 groups, depending on the presence of bone sclerosis (ie, with or without) in the host bone just below the osteochondral fragment (nonsclerosis group and sclerosis group). The area of BML was compared between the 2 groups. Biopsies of the osteochondral fragment from 20 ankles were performed during surgery, and the correlation between the BML and cartilage degeneration was analyzed. The remaining 13 ankles had the CT and MRI compared with the arthroscopic findings. Results: The mean area of BML in the nonsclerosis group was significantly larger than that in the sclerosis group. In the histologic analysis, there was a significant and moderate correlation between the Mankin score and the area of BML. The mean Mankin score in the nonsclerosis group was significantly lower than that in the sclerosis group. Conclusions: This study revealed that a large area of BML on MRI exhibited low degeneration of cartilage of the osteochondral fragment, while a small area of BML indicated sclerosis of the subchondral bone with severe degeneration of cartilage. The evaluation of BML may predict the cartilage condition of the osteochondral fragment. Level of Evidence: Level III, comparative series.