Search

Background: The Herring lateral pillar classification is widely used for the classification of Legg-Calvé-Perthes disease, but is not applied at the early stage of Legg-Calvé-Perthes disease because it is typically applied at the late fragmentation stage. The purpose of this study was to investigate the correlation between the early appearance on magnetic resonance imaging of the acetabular labrum and lateral pillar involvement in Legg-Calvé-Perthes disease., Methods: Non-contrast magnetic resonance images of 26 hips in 25 children with early-stage Legg-Calvé-Perthes disease were retrospectively reviewed. The extent of labral horizontalization was quantitatively evaluated with a new method, the labral angle, on T2*-weighted magnetic resonance images. A small labral angle indicates strong labral horizontalization. Calculation of the teardrop distance and acetabular head index on radiographs was modified for application to magnetic resonance imaging, and the extent of cartilaginous lateral subluxation (cartilaginous tear drop distance) and cartilaginous lateral extrusion (cartilaginous acetabular head index) were evaluated. The outcome measure was the lateral pillar classification., Results: There were statistically significant correlations between the labral angle and the cartilaginous tear drop distance (p = 0.002, ɤ = -0.58) and the cartilaginous acetabular head index (p < 0.001, ɤ = 0.65) on magnetic resonance images. The labral angle was small in order of groups C, B, and A, and there were significant differences between groups A and C (p < 0.001) and B and C (p = 0.006)., Conclusion: Greater labral horizontalization observed on magnetic resonance imaging at the early stage of Legg-Calvé-Perthes disease correlated with strong cartilaginous lateral subluxation and extrusion, and with increased lateral pillar collapse at the maximum fragmentation stage. Our finding suggests that a quantitative evaluation of labral horizontalization using magnetic resonance imaging in the early-stage of Legg-Calvé-Perthes disease can predict the later lateral pillar classification., (Copyright © 2017 The Japanese Orthopaedic Association. Published by Elsevier B.V. All rights reserved.)

Recently, more attention has been paid to the role of the acetabular labrum. Therefore, we designed a retrospective cohort study of patients with residual hip dysplasia (RHD) who underwent magnetic resonance imaging (MRI). The objective of this study was to investigate an association between the MRI appearance of the labrum before school age and the natural history of RHD.We retrospectively investigated 45 hips of 40 patients who underwent MRI at about 3 and 4 years of age for RHD and were conservatively followed up with until 6 years of age or older. We evaluated the extent of eversion with a new method that measures the β angle (MRI β angle) using landmarks of the Graf method on MRI T2*-weighted images. The outcome measure was the Severin classification at the final follow-up. We compared the radiographic and MRI parameters at approximately 3 and 4 years of age between the good and poor outcome groups. The Student t test or one-way analysis of variance was used to compare the quantitative variables between groups. The Chi-square test was used to perform a ratio comparison.Although there was a significant difference in the center-edge (CE) angle, there was no significant difference in the acetabular index and the ratio of the presence of femoral head necrosis and the break in Shenton line between the good and poor groups. The MRI β angle was significantly greater in the poor outcome group than in the normal and good outcome groups. The cut-off value of the MRI β angle to differentiate the good and poor outcome groups was 65°, and its specificity and sensitivity were 92% and 53%, respectively.There was labral eversion on MRI scans in patients with RHD. Acetabular development before adolescence was poorer with greater labral eversion on MRI scans. The specificity for poor acetabular development was high when the MRI β angle was 65° or more. The MRI β angle has the potential to predict acetabular development.