- Etiology: abnormalities of intrauterine positioning, breech presentation (20%)
- US Normal:
— alpha (bony) angle (>60 degrees) and beta (cartilaginous) angle (< 55 degrees) and there is > 50% coverage of femoral head - US Immature:
— age < 3 months and alpha angle is 50-59 degrees - US Dysplastic:
— age < 3 months and alpha angle is < 50 degrees, age > 3 months and alpha angle is 50-59 degrees, hip has < 50% coverage of femoral head, beta angle > alpha angle, beta angle > 55 degrees means lateral displacement - Radiograph:
— Asymmetric ossification of femoral epiphyses with the dysplastic side have delayed ossification due to delayed epiphyseal development
— Lines for hip dislocation:
— Hilgenreiner’s line through the bilateral triradiate cartilage horizontally
— Perkin’s line is perpendicular to Hilgereiner’s line through superolateral corner of acetabulum, it should bisect middle third of metaphysis, femoral ossification center should be medial to Perkin’s line in lower inner quadrant
— Shenton line is a smooth curve along the inferior border of the superior pubic ramus and along the inferomedial border of the neck of femur
— Acetabular angle is line along roof of acetabulum to Hilgereiner’s line and is < 30 degrees at birth and decreases to 22 degrees at 1 year, is increased in developmental dysplasia of hip / neuromuscular disorders / achondroplasia / first year of life in Trisomy 21 - Complications: if missed see acetabular dysplasia / pseudoacetabulum -> leg length discrepancies, limp, pain, osteoarthritis
- Clinical: for patients with positive Barlow and Ortolani manueuver get US at 2 weeks and for breech birth get hip US at 4-6 weeks up to 8-10 months and after 4-6 months can do radiograph for screening
Radiology Cases of Developmental Dysplasia of the Hip


