Pubo-femoral distance in selective ultrasound screening of developmental dysplasia of the hip.

BACKGROUND: Developmental dysplasia of the hip (DDH) incidence is already debated due to different types of screening techniques. Despite of that, timely treatment of this pathology is necessary to reduce complications on the hip joint.

METHODS: A retrospective study has been performed on the incidence of DDH in Marche region (Italy) in 2017. Epidemiological data have been collected and evaluated. 302 ultrasound images stored in the hospital archives were selected to measure pubo-femoral distance (PFD) and bony rim percentage (BRP). PFD and BRP values were compared with α and β angles measured by Graf method.

RESULTS: DDH incidence was 12%. Girls were more affected than males (ratio 3:1). Right side was more involved, 20% of patient had familiarity with DDH, 7% were breech babies and 15% suffered from other congenital orthopedic diseases. PFD in pathological hips was 3.21 mm (0.60-7 mm) and 2.47 mm (0.80-5.30 mm) in normal hips (P<0.005). Dispersion of PFD with respect to α and β angles showed that PFD grows with increasing β angle values and decreasing α angles. BRP in pathological hips was 47.29%, while in normal hips was 49.53% (<3 months). BRP was 49.71% in normal hips and 45.83% in pathological ones (>3 months). BRP measurement did not match the expected results, requiring more studies before its adoption in clinical practice.

CONCLUSIONS: Our study evidenced the DDH incidence in Marche region and helped to validate a new screening technique consisting in measuring of PFD. For a full BRP validation, future studies will still be required.