CONGENITAL HIP DYSPLASIA

Issah J. kiswagala

(M.B.B.S)

INTRODUCTION

• Congenital Hip Dysplasia (CHD) or Development Dysplasia of the Hip (DDH)
• Hip dysplasia is an abnormality of the hip joint where the socket portion does not fully cover the ball portion, resulting in an increased risk for joint dislocation. The acetabular(socket) or Femur head is deformed
• By definition: Developmental dysplasia of the hip (DDH) is a disorder of abnormal development resulting in dysplasia, subluxation, and possible dislocation of the hip secondary to capsular laxity and mechanical factors

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EPIDEMIOLOGY

• Incidence
• 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 and black skin color individual

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• 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%
• According to Barlows study, more than 60% of newborn with hip instability become stable by age 1 week and 88% become stable by age 2 month leaving only 12%(of 1in 60 newborn or 0.2% overall)with residual hip instability.

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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

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• Family history
• Oligohydramnios
• Newborns with greater weight and height
• Deformities of the feet or spine
• White skin color
• Primiparity
• Young mother

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AETIOLOGY

• Multifactorial condition. That means that several factors are involved in causing the condition to manifest.

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• The cause of this condition is unknown; however, some factors of congenital hip dislocation are through heredity and racial background.

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• Genetic disposition also appear to exist in the frequency of hip dysplasia is 10 times higher in the whose parent had DDH than those whose parent did not

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PATHOANATOMY

1. Initial instability thought to be caused by maternal and fetal laxity, genetic laxity, and intrauterine and postnatal malpositioning
• This initial instability leads to dysplasia. typical deficiency is anterior or anterolateral acetabulum
2. Dysplasia leads to subluxation and gradual dislocation
• Repetitive subluixation of the femoral head leads to the formation of a ridge of thickened articular cartilage called the limbus
3. Chronic dislocation leads to
• Development of secondary barriers to reduction

• Anatomic changes
• Increased femoral anteversion
• Flattening of the femoral head
• Increased acetabular anteversion
• Increased obliquity and decreased concavity of the acetabular roof
• Thickening of the medial acetabular wall

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SPECTRUM OF DISEASE

• 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

4. 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
5. late (adolescent) dysplasia
• mechanically stable and reduced but dysplastic

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ASSOCIATED CONDITIONS

• Associated with "packaging" deformities which include
• Congenital muscular torticollis (20%)
• Metatarsus adductus (10%)
• Congenital knee dislocation
• Conditions characterized by increased amounts of type III collagen

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CLASSIFICATION

• Can be classified as a range of disease involvement (phases)
• Subluxable
• Barlow-suggestive
• Dislocatable
• Barlow-positive
• Dislocated
• Ortolani-positive early when reducible; Ortolani-negative late when irreducible

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CLINICAL PRESENTATION

• Depend on the level of dysplasia (mild, moderate severe)
• Turning or positioning legs abnormally
• Shortening of limb
• Abnormal mobility
• Osteoarthritis if hip dysplasia is not diagnosed
• Feature of Hip Dislocation

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INVESTIGATIONS

• Radiograph
• Indications
• becomes primary imaging modality at 4-6 months after the femoral head begins to ossify
• positive physical exam
• leg length discrepancy
• Recommended views
• AP of pelvis

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• 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
• CT scan and MRI

TREATMENT

• The treatment is age related:

NON-OPERATIVE

1. Abduction splinting/bracing (Pavlik harness)

Indications

• Below 6 months old and reducible hip
• Requires normal muscle function for successful outcomes
• Contraindicated in teratologic hip dislocations and patients with spina bifida or spasticity
• Splints like Von Rosen’s splints – Below 3 months old

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2. Closed reduction and spica casting

Indications

• 6-18 months old
• Failure of Pavlik treatment

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• Gentle manipulation under GA then POP in "human position" . (not Frog position ) – 3 to 6 months

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OPERATIVE

1. Open reduction and spica casting
• Indications
• Above 18 months old
• Failure of closed reduction
2. Open reduction and femoral osteotomy
• Indications
• Above 2 years old with residual hip dysplasia
• anatomic changes on femoral side (e.g., femoral anteversion, coxa valga)
• best in younger children (< 4 years old)
• after 4 years old, pelvic osteotomies are utilized

3. Open reduction and pelvic osteotomy
• Indications
• Above 2 years old with residual hip dysplasia
• severe dysplasia accompanied by significant radiographic changes on the acetabular side (increased acetabular index)
• used more commonly in older children (> 4 yrs.)
• decreased potential for acetabular remodeling as child ages

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COMPLICATIONS

• Avascular Necrosis (AVN) - Seen with all forms of treatment
• Delayed diagnosis with frequent dislocations
• Transient femoral nerve palsy
• Pavlik disease (erosion of the pelvis superior to the acetabulum)
• Recurrence - approximately 10% with appropriate treatment