Ultrasound Characteristics of Clinically Dislocated But Reducible Hips With DDH

Area of Science:

• Pediatric Orthopedics
• Diagnostic Imaging
• Developmental Dysplasia of the Hip

Background:

• Ultrasound (US) is crucial for diagnosing and managing infantile developmental dysplasia of the hip (DDH).
• Precise ultrasonographic parameters for hip dislocation and subluxation remain undefined.
• This study addresses the need for standardized US definitions in DDH.

Purpose of the Study:

• To describe ultrasonographic characteristics of a large cohort of clinically dislocated but reducible hips.
• To develop standardized ultrasonographic definitions for hip dislocation and subluxation in infants.
• To establish reliable US criteria for early DDH diagnosis.

Main Methods:

• Retrospective review of prospectively collected data from an international multicenter study.
• Inclusion of infants under 6 months with Ortolani-positive hips (dislocated at rest but reducible).
• Measurement of femoral head coverage (FHC), alpha angle (α), and beta angle (β) on pretreatment ultrasound.

Main Results:

• Median FHC was 10% (IQR 0-23%), with 39% of hips showing 0% FHC.
• The 90th percentile for FHC was 33%.
• Median α was 43° (IQR 37-49°), and median β was 66° (IQR 57-79°).

Conclusions:

• A femoral head coverage (FHC) of ≤33% on initial US appears to be a sensible definition for hip dislocation.
• FHC between 34% and 50% may indicate hip subluxation.
• Further prospective research is needed to validate these proposed ultrasonographic thresholds for DDH.