MRI at 5 years predicts upsloping acetabular sourcil at skeletal maturity in developmental dysplasia of the hip

INTRODUCTION: Acetabular sourcil morphology has been linked to hip instability and pain. We investigated whether MRI findings at age 5 years predict sourcil morphology at skeletal maturity in developmental dysplasia of the hip (DDH). METHODS: We retrospectively reviewed 71 surgically treated hips that were followed to skeletal maturity. On final anteroposterior radiographs, the sourcil was classified as type A (downsloping), type B (horizontal), or type C (upsloping). Coronal MRI at 5 years was used to measure bony, cartilaginous, and labral acetabular indices and centre-edge angles, and the labral junction obliquity angle (LJOA). Predictors of type C morphology were assessed using multivariable logistic regression and ROC analyses. RESULTS: At 5 years, radiographic acetabular index and centre-edge angle did not differ among sourcil types. In contrast, hips that developed type C morphology showed smaller cartilaginous and labral centre-edge angles and a smaller LJOA on MRI. In multivariable analysis, a smaller cartilaginous centre-edge angle and a smaller LJOA independently predicted type C morphology. Optimal cutoff values were 23° for the cartilaginous centre-edge angle (AUC 0.902) and 89° for the labral junction obliquity angle (AUC 0.964). CONCLUSION: MRI at age 5 years may help identify DDH hips at risk of developing an upsloping sourcil at skeletal maturity.