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.
13 year old girl with neglected DDH operated with concentric reduction of head
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%)
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
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