Osteochondral lesion of the talus in children. Are there MRI findings of instability?

The purpose of our study was to investigate the performance of MRI findings to predict instability of osteochondral lesion of the talus (OLT) in children and the association between skeletal maturity and lesion stability. This retrospective IRB-approved and HIPPA-compliant study included children with OLT, who underwent an ankle MRI examination between March 1, 2011, and May 31, 2018. Blinded to the clinical outcome, 2 radiologists retrospectively assessed each MRI study for the presence or absence of various features on the articular side, along the interface, and on the subchondral side of each lesion. Regional skeletal maturity was recorded. Lesion stability was classified using clinical and surgical findings. Mann-Whitney U, Chi-square, Fisher's exact, and Cochran-Armitage tests were used to compare demographic and MRI findings between children with stable and unstable lesions. Of the 48 ankles identified, 36 were stable (12.7 $\pm$ 3.9 years) and 12 were unstable (14.2 $\pm$ 1.6 years) lesions. None of the lesions presented as a detached fragment. Skeletal immaturity (p = 0.01) was significantly more common in stable than unstable lesions. No other MRI features were found to be significantly different between stable and unstable lesions, which included the presence of an effusion (p = 0.27), intra-articular body (p = 0.25), cartilage changes (p = 0.19), subchondral disruption (p = 0.51), T2-weighted signal intensity rim (p = 0.16), cysts (p = 0.48), marginal sclerosis (p = 0.70), and perilesional marrow edema (p = 0.17). Results from our study suggest that previously published OCD criteria using conventional MRI are not sufficient for predicting stability of OLT in children. Regional skeletal maturity and older age were more predictive of unstable lesions.