Quantitative MRI Analysis of the Talocrural and Talonavicular Joints in Ballet Dancers.

The ankles of ballet dancers are routinely under heavy loading that may lead to osteoarthritic changes. It would be clinically useful to identify such pathology as early as possible in a dancer's career. Therefore, the purpose of this study was to compare quantitative measurements in magnetic resonance (MR) images of the talocrural and talonavicular joints in ballet dancers and healthy non-dancers for use in formulating prediction of chronic injury and degenerative joint disease in these locations. Quantitative measurements in MR images of the talocrural and talonavicular joints were compared in 10 female ballet dancers, 10 healthy female non-dancers, and nine male ballet dancers. Fat-suppressed density-weighted proton, T1rho, and T2 mapping images were acquired with a 3.0 T MR scanner. Medial and lateral subchondral bone distance between the tibia and talus (MSBD and LSBD), axial navicular-talus axis angle (ANT angle), sagittal talar neck angle against the posterior talocalcaneal joint (TN angle), and curvature of navicular surface at the talonavicular joint were measured on sagittal images. The medial subchondral bone distance was found to be significantly larger in female dancers than female non-dancers (4.05 mm vs. 2.75 mm, p < 0.05), whereas there were no significant differences in LSBD (2.63 mm vs. 2.63 mm, p = 0.87). Axial navicular talus angles in female dancers were significantly larger than those in female non-dancers (38.9° vs. 24.3°, p < 0.05). There was a tendency for the TN angle to be smaller and navicular curvature (NC) to be larger in female dancers compared to female non-dancers, though the differences were not significant (TN angle: 16.6° vs. 22.3°, p = 0.09, and NC: 0.186 vs. 0.165, p = 0.28). There were no significant differences in T1rho or T2 values of talonavicular joint cartilage. These results show that the bony anatomy of dancers' ankles may adapt to the stresses placed on them by ballet.