Towards Reliable Automatic Characterization of Neonatal Hip Dysplasia from 3D Ultrasound Images

Ultrasound (US) imaging is recommended for early detection of developmental dysplasia of the hip (DDH), which includes a spectrum of hip joint abnormalities in infants. However, the currently standard 2-dimensional (2D) US-based approach to measuring the dysplasia metric (DM), namely the α angle, suffers from high within-hip variability with standard deviations typically ranging between 3◦ − 7◦. Such high variability leads to elevated overand under-treatment rates in hip classification. To reduce this high variability inherent to the 2D α angle, α2D, we propose a 3D US-based DM in the form of a 3D α angle, α3D, that more accurately characterizes the morphology of an infant’s hip joint. Our method leverages phase symmetry features that automatically identify the 3D bone/cartilage structures to compute α3D. Validating on 30 clinical patient hip examinations, we demonstrate the within-hip variability of α3D to be significantly smaller than α2D (28.9% reduction, p < 0.01). Our findings indicate that α3D may be significantly more reproducible than the conventional 2D measure, which will likely reduce misclassification rates.