Developmental Dysplasia of the Hip

  • 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
    — dysplastic 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
    — Hilgereiner’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’s line is a smooth curve
    — 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, if increased (developmental dysplasia of hip, neuromuscular disorders, achondroplasia, first year of life in Trisomy 21)
  • Complications: if missed see acetabular dysplasia / pseudoacetabulum -> 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

Cases of Developmental Dysplasia of the Hip

Radiograph of developmental dysplasia of the hip
Frogleg radiograph of the pelvis shows markedly asymmetrical ossification of the femoral epiphyses, with the left femoral epiphysis smaller in size than the right femoral epiphysis. The left acetabulum is also more shallow than the right acetabulum and the left femoral epiphysis appears slightly subluxed laterally and superiorly.