Correlation of the pathologic morphology on MRI with International Hip Dysplasia Institute classification in developmental dysplasia of the hip / 中国组织工程研究

ABSTRACT

BACKGROUND: T?nnis classification is commonly used to quantify the severity of developmental dysplasia of the hip (DDH), which relies on the presence of the epiphyseal ossification centre. Thereafter, a new classification system (IHDI method) has been developed by the International Hip Dysplasia Institute (IHDI). However, the pathologic morphology has not been defined based on the IHDI grade.OBJECTIVE: To analyze the correlation of the pathologic changes of the hip on MRI with IHDI classification.METHODS: Image data of 65 infants (89 hips) with DDH were analyzed retrospectively, with an average age of 20.4 months. The radiographic severity was graded by IHDI system, and the correlation between IHDI classification and pathological changes of the hip was analyzed, by observing the morphology and position of the limbus, and the cartilaginous acetabular index.RESULTS AND CONCLUSION: (1) A positive correlation was detected between severity of the IHDI grades and age at reduction (r=0.456, P < 0.001). (2) Unexpectedly, the cartilaginous femoral epiphysis still remained contacting with the acetabulum in a part of type III DDH. The cartilaginous acetabular index was significantly increased with IHDI grade increasing (P=0.028). (3) The limbus was everted in all of the type I hips; however, inverted or mixed shape accounted about 60% in the type II hips, 86% in the type III, and 97% in the type IV, respectively. (4) These results manifest that the DDH was severer, and the limbus trended to be more inverted with the increasing in IHDI grade. Moreover,understanding the correlation of the pathologic morphology with the IHDI classification is of great significance for planning an appropriate treatment scheme for DDH.