Ultrasound features predicting the 3-week outcome of Pavlik harness treatment for developmental hip dysplasia.

Background: The treatment protocol for children with developmental dysplasia of the hip (DDH) is routinely adjusted by assessing the hip reduction after 3 weeks of Pavlik harness treatment. However, there is a high risk of failure and complications in the treatment adjustment. The aim of this study was to explore the value of ultrasound features in predicting the treatment outcome of Pavlik harness after 3 weeks in DDH children.

Methods: A total of 215 DDH children were recruited and the demographics and the changes of ultrasound features [α and β angle and femoral head coverage (FHC)] during the Pavlik harness treatment were recorded. The children were divided into the success group and the failure group according to the reduction outcome after 3 weeks. Univariate and multivariate analyses were performed to analyze the independent predictors for the treatment outcome. Repeated-measures analysis of variance was used to compare the changes of ultrasound features between the two groups during the treatment. Receiver operating characteristic (ROC) curves were plotted to analyze the predictive accuracy of the ultrasound features.

Results: Graf type III (P=0.036), bilateral dislocation (P=0.031), and age at diagnosis (P=0.021) were associated with an increased risk of Pavlik harness failure in the multivariate analysis. The changes in α and β angle and FHC were generally greater in the success group than in the failure group. The α angle and FHC were larger in the success group, while the β angle was larger in the failure group (P<0.05). Each ultrasound parameter (α and β angle and FHC) alone could not accurately predict the treatment outcome within 3 weeks. However, the combined ultrasonic features at the second week could accurately predict the outcome of Pavlik harness treatment after the third week. The combination of the ultrasound features at the first week and the influencing factors (Graf classification, age at diagnosis, and side of pathology) could accurately predict the outcome at the first week [area under curve (AUC) =0.931, sensitivity =82.14%, specificity =97.86%].

Conclusions: The combined model of ultrasonic features at the second week could accurately predict the reduction outcome of Pavlik harness after the third week. The combined model including independent predictors and ultrasonic features could accurately predict the reduction outcome at the first week.