DDH

Developmental Dysplasia of the Hip

  • Developmental Dysplasia of the Hip is a disorder of abnormal development resulting in dysplasia, subluxation, and possible dislocation of the hip secondary to capsular laxity and mechanical instability.

  • Diagnosis can be confirmed with ultrasonography in the first 4 months and then with radiographs after femoral head ossification occurs (~ 4-6 months).

  • Treatment varies from Pavlik bracing to surgical reduction and osteotomies depending on the age of the patient, underlying etiology, and the severity of dysplasia.

    • most common orthopaedic disorder in newborns

    • dysplasia is 1:100

    • dislocation is 1:1000

  • Demographics

    • more common in females (6:1)

    • more commonly seen in Native Americans and Laplanders

      • due to cultural traditions such as swaddling with hips together in extension

    • rarely seen in African Americans

    • Anatomic location

      • most common in left hip (60%)

        1. due to the most common intrauterine position being left occiput anterior (left hip is adducted against the mother's lumbrosacral spine)

      • bilateral in 20%

  • Risk factors

    • firstborn

      • due to unstretched uterus and tight abdominal structures compressing the uterus

    • female

      • due to increased ligamentous laxity that transiently exists as the result of circulating maternal hormones and the estrogens produced by the fetal uterus

    • breech

      • more commonly seen in female children, firstborn children, and pregnancies complicated by oligohydramnios

      • higher risk of DDH with frank/single breech position compared to footling breech position

    • family history

    • oligohydramnios

    • macrosomia

    • limited hip abduction

    • talipes

    • swaddling

DDH encompasses a spectrum of disease that includes

  • dysplasia

    • shallow or underdeveloped acetabulum

  • subluxation

    • displacement of the joint with some contact remaining between the articular surfaces

  • dislocation

    • complete displacement of the joint with no contact between the original articular surfaces

  • teratologic hip

    • dislocated in utero and irreducible on neonatal exam

    • presents with a pseudoacetabulum

    • associated with neuromuscular conditions and genetic disorders

    • commonly seen with arthrogryposis, myelomeningocele, Larsen's syndrome, Ehlers-Danlos

  • late (adolescent) dysplasia


  • pathoanatomy

    • initial instability leads to dysplasia

      • typical deficiency is anterior or anterolateral acetabulum

        • in spastic cerebral palsy, acetabular deficiency is posterosuperior

    • dysplasia leads to subluxation and gradual dislocation

      • repetitive subluxation of the femoral head leads to the formation of a ridge of thickened articular cartilage called the limbus

    • chronic dislocation leads to

      • development of secondary barriers to reduction

        • pulvinar thickens

        • ligamentum teres thickens and elongates

        • transverse acetabular ligament hypertrophies

        • hip capsule and iliopsoas form hourgass configuration

Ultrasound

  • indications

    • primary imaging modality from birth to 4 months

      • may produce spurious results if performed before 4-6 weeks of age

    • positive physical exam

    • risk factors (family history or breech presentation)

      • AAP recommends an US study at 6 weeks in patients who are considered high risk (family history or breech presentation) despite normal exam

    • monitoring of reduction during Pavlik harness treatment

    • most studies show it is not cost effective for routine screening


Radiograph

  • indications

    • becomes primary imaging modality at 4-6 mo after the femoral head begins to ossify

    • positive physical exam

    • leg length discrepancy

  • recommended views

    • AP of pelvis