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

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).

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.

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).

MRI at age 5 years may help identify DDH hips at risk of developing an upsloping sourcil at skeletal maturity.