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
  • 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

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.
US of development dysplasia of the hip
Coronal US of the bilateral hips shows lateral subluxation of the left femoral head out of the left acetabulum with less than 50% coverage of the left femoral head and a decreased alpha angle of the left hip of 45 degrees. There is a normal alpha angle of the right hip of 69 degrees and the right femoral head is > 50% covered.
US of developmental dysplasia of the hip
Coronal ultrasound images of the left hip (left) and right hip (right) were obtained after 5 weeks of therapy in a Pavlik harness with the patient located in the Pavlik harness during the exam. The coronal view is meant to simulate an anterior-posterior radiograph of the hip. The left hip is still dysplastic with there still being a shallow acetabulum and decreased alpha angle even though the left hip appears fairly well located in the left acetabulum. The left hip alpha angle measured 45 degrees (normal is usually greater than 60 degrees) but had increased since the last exam. The right hip was normal in appearance.