| Introduction |
- A disorder of abnormal development resulting in dysplasia and possible subluxation or dislocation of the hip secondary to capsular laxity and mechanical factors
- DDH encompasses a spectrum of disease that includes
- dysplasia
- a shallow or underdeveloped acetabulum
- subluxation
- dislocation
- 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
- late (adolescent) dysplasia
- mechanically stable and reduced but dysplastic
- Epidemiology
- incidence
- most common orthopaedic disorder in newborns
- dysplasia is 1:100
- dislocation is 1:1000
- location
- most common in left hips in females
- demographics
- more commonly seen in Native Americans and Laplanders
- rarely seen in African Americans
- risk factors
- firstborn
- female (6:1 over males)
- breech
- family history
- oligohydramnios
- Pathophysiology
- initial instability thought to be caused by maternal and fetal laxity, genetic laxity, and intrauterine and postnatal malpositioning
- pathoanatomy
- initial instability leads to dysplasia
- dysplasia leads to gradual dislocation
- typical deficiency is anterior or anterolateral acetabulum
- in spastic cerebral palsy, acetabular deficiency is posterior-superior
- 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 spectrum of disease involvement (phases)
- dislocated
- Ortolani-positive early when reducible; Ortolani-negative late when irreducible
- dislocatable
- subluxatable
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| Presentation |
- Physical exam (< 3 months)
- mainstay of physical diagnosis is palpable hip subluxation/dislocation on the exam
- Barlow
- dislocates a dislocatable hip by adduction and depression of the flexed femur
- Ortolani
- reduces a dislocated hip by elevation and abduction of the flexed femur
- Galeazzi (Allis)
- apparent limb length discrepancy due to a unilateral dislocated hip with hip flexed at 90 degrees and feet on the table
- femur appears shortened on dislocated side
- hip clicks are nonspecific findings
- Barlow and Ortolani a rarely positive after 3 months of age because of soft-tissue contractures about the hip
- Physical exam (> 3 months to 1 year)
- limitations in hip abduction
- most sensitive test once contractures have begun to occur
- occurs as laxity resolves and stiffness begins to occur
- decreased symmetrically in bilateral dislocations
- leg length discrepancy predominate
- Physical exam (> 1 year - walking child)
- pelvic obliquity
- lumbar lordosis
- in response to hip contractures resulting from bilateral dislocations in a child of walking age
- Trendelenburg gait
- results from abductor insufficiency
- toe walking
- compensate for the relative shortening of the affected side
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| Imaging |
- 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
- measurements
- hip dislocation
- Hilgenreiner's line
- a horizontal line through right and left triradiate cartilage
- femoral head ossification should be inferior to this line
- Perkin's line
- line perpendicular line to Hilgenreiner's through a point at lateral margin of acetabulum
- femoral head ossification should be medial to this line
- Shenton's line
- arc along inferior border of femoral neck and superior margin of obturator foramen
- arc line should be continuous
- delayed ossification of the femoral head is seen in cases of dislocation
- hip dysplasia
- acetabular index (AI)
- the angle formed by a line drawn from a point on the lateral triradiate cartilage to point on lateral margin of acetabulum and Hilgenreiners line
- should be less than 25° in patients older than 6 months
- center-edge angle (CEA) of Wiberg
- the angle formed by a vertical line from the center of the femoral head and a line from the center of the femoral head to the lateral edge of the acetabulum
- less than 20° is considered abnormal
- reliable only in patients over the age of 5 years
- acetabular teardrop not typically present prior to hip reduction for chronic dislocations since birth
- development of teardrop after reduction is thought to be a good prognostic sign for hip function
- 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)
- the AAP recommends a 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 is not cost effective for routine screening
- findings
- evaluates for acetabular dysplasia and/or the presence of a hip dislocation
- allows view of bony acetabular anatomy, femoral head, labrum, ligamentum teres, hip capsule
- normal ultrasound in patients with soft-tissue 'clicks' will have normal acetabular development
- measurements
- alpha angle
- the angle created by lines along the bony acetabulum and the ilium
- normal is greater than 60°
- beta angle
- the angle created by lines along the labrum and the ilium
- normal is less than 55°
- femoral head is normally bisected by a line drawn down from the ilium
- Arthrogram
- indications
- used to confirm reduction after closed reduction under anesthesia
- help identify possible blocks to reduction
- inverted labrum
- labrum enhances the depth of the acetabulum by 20% to 50% and contributes
to the growth of the acetabular rim
- in the older infant with DDH the labrum may be inverted and may mechanically block concentric reduction of the hip
- inverted limbus
- represents a pathologic response of the acetabulum to abnormal pressures caused by superior migration of the head
- consists of fibrous tissue
- transverse acetabular ligament
- hip capsule is constricted by iliopsoas tendon causing hour-glass deformity of the capsule
- pulvinar
- ligamentum teres
- CT
- CT is historically the study of choice to evaluate reduction of the hip after closed reduction and spica casting
- MRI
- increasingly used to evaluate reduction of hip after closed reduction and spica casting, to minimize radiation compared to CT.
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| Screening |
- All infants require screening
- physical exam
- successful screening requires repetitive screening until walking age
- ultrasound
- ultrasound screening of all infants occurs in many countries, however, it has not been proven to be cost-effective
- USA recommendation is to perform ultrasound at 4 to 6 weeks in patients with
- risk factors
- positive physical findings
- utilized to follow Pavlik treatment or for equivocal exams
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| Treatment in Children |
- Nonoperative
- abduction splinting/bracing (Pavlik harness)
- indications
- DDH < 6 months of age and reducible hip
- Pavlik harness treatment is contraindicated in teratologic hip dislocations
- is a dynamic splint that requires normal muscle function for successful outcomes
- contraindicated in patients with spina bifida or spasticity
- outcomes
- overall Pavlik harness has a success rate of 90%
- dependent upon age at initiation of treatment and time spent in the harness
- abandon Pavlik harness treatment if not successful after 3-4 weeks
- If Pavlik harness fails, consider converting to semi-rigid abduction brace with weekly ultrasounds for an addition 3-4 weeks before considering further intervention
- closed reduction and spica casting
- indications
- DDH in 6 - 18 months of age
- failure of Pavlik treatment
- arthrography performed at the time of reduction
- medial dye pool >7mm associated with poor outcomes and osteonecrosis
- wide abduction associated with osteonecrosis (aim at <55 degrees abduction)
- Operative
- open reduction and spica casting
- indications
- DDH in patient >18 months of age
- failure of closed reduction
- open reduction and femoral osteotomy
- indications
- DDH > 2 yr with residual hip dysplasia
- anatomic changes on femoral side (e.g., femoral anteversion, coxa valga)
- femoral head should be congruently reduced with satisfactory ROM, and reasonable femoral sphericity
- best in younger children (< 4 yr)
- after 4 yr, pelvic osteotomies are utilized
- open reduction and pelvic osteotomy
- indications
- DDH > 2 yr 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 yr)
- decreased potential for acetabular remodeling as child ages
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| Techniques |
- Abduction splinting/bracing (Pavlik harness)
- goals
- treatment is based on an early concentric reduction in order to prevent future degeneration of the hip
- risk, complexity, and complications are increased with delays in diagnosis
- position in bracing
- the anterior straps flex the hips to 90-100° flexion and prevent extension
- the posterior prevent adduction of the hips
- extreme positions can cause
- AVN due to impingement of the posterosuperior retinacular branch of the medial femoral circumflex artery
- seen with extreme abduction (> 60°)
- placement of abduction within 'safe zone'
- transient femoral nerve palsy
- discontinue if hip is not reduced by 3-4 weeks to prevent Pavlik disease
- erosion of the pelvis superior to the acetabulum and prevention of the development of the posterior wall of the acetabulum
- worn for 23 hours/day for at least 6 weeks or until hip is stable
- wean out of harness over 6-8 weeks after hip has stabilized until normal anatomy develops
- confirm position with ultrasound or xray and monitor every 4-6 week
- Closed reduction and spica casting
- performed under general anesthesia
- excessive force can result in AVN
- arthrogram used to confirm the reduction
- concentric reduction must be obtained with less than 5mm of contrast pooling medial to femoral head and the limbus must not be interposed
- the arthrogram will also help identify anatomic blocks to reduction
- spica casting
- following reduction immobilize in a spica cast with hip flexion of 100° and abduction of 45°with neutral rotation for 3 months
- 'human position'
- change cast at 6 weeks
- adductor tenotomy performed if the patient has an unstable safe zone
- used if excessive abduction required to maintain the reduction
- confirm reduction with CT scan in spica cast with selective cuts to minimize radiation to the child
- Open reduction
- anterior approach (Smith-Peterson) most common to decrease risk to the medial femoral circumflex artery
- capsulorrhaphy can be performed after reduction
- used if the patient is older than 12 months
- medial approaches
- pros
- directly addresses block to reduction
- can be used in patients under 12 months of age
- less blood loss
- cons
- unable to perform a capsulorrhaphy
- higher association of AVN
- Ludloff medial approach
- between pectineus and adductor longus and brevis
- Weinstein anteromedial approach
- between neurovascular bundle and pectineus
- Ferguson posteromedial approach
- superficially between adductor longus and gracilis
- deep between adductor brevis and adductor magnus
- remove possible anatomic blocks to reduction
- iliopsoas contracture, capsular constriction, inverted labrum, pulvinar, hypertrophied ligamentum teres
- adductor tenotomy performed if the patient has an unstable safe zone
- if excessive abduction required to maintain the reduction
- immobilize in functional position of 15° of flexion, 15° of abduction and neutral rotation
- Femoral Osteotomy (VRDO)
- used to correct excessive femoral anteversion and/or valgus
- femoral osteotomy and shortening may be needed to prevent AVN
- decrease tension produced by reduction of a previously dislocated hip
- Pelvic Osteotomies
- indications
- increase anterior or anterolateral coverage
- used after reduction is confirmed on abduction-internal rotation views and satisfactory ROM has been obtained
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