PEDBASE.org - The Pediatric Database - Detailed information of DEVELOPMENTAL DYSPLASIA OF THE HIP

DEVELOPMENTAL DYSPLASIA OF THE HIP

DEFINITION:

A congenital disorder of the hip caused by the abnormal development of one or all of the components of the hip joint.

EPIDEMIOLOGY:

incidence: 1-1.5/1000 live births
age of onset:
- newborn -> toddler
risk factors:
- F > M (9:1)
- see below

PATHOGENESIS:

1. Background

in the past, referred to as "Congenital Dislocation of the Hip (CDH)"
may be two types:
- typical - in the neurologically normal infant
- teratologic - in infants with an underlying neuromuscular disorder (i.e., myelodysplasia)
60% are left-sided, 20% right-sided, and 20% are bilateral

2. Etiology (Multifactorial)

1. Genetic

family history in up to 33%% of cases
associated with a hereditary reduction in acetabular depth or ligamentous laxity
seen more frequently in certain disorders:
- Arthrogryposis
- Cerebral Palsy
- Lawson's Syndrome
- Spina Bifida
- Trisomies 18 and 21
- Turner Syndrome

2. Environmental

due to mechanical factors such as:
- maternal estrogen
- breech delivery (with hips flexed and knees extended)
- crowding (multiple births)
- oligohydramnios
- traumatic delivery (hyperextension of hips & knees)
- first born child (due to unstretched primigravida uterus and abdominal muscles)
- congenital muscular torticollis

3. Differential Diagnosis

congenital short femur
congenital coxa vargum
septic dislocation of the hip

CLINICAL FEATURES:

1. Newborn/Infant

1. Dislocated Hip

loss of normal flexion contracture of the affected hip
decreased abduction in flexion (<60-70 degrees) with adduction contracture in those older than 4 weeks of age
positive Ortoloni Test
- for dislocated hip
- a "clunk" is heard on reduction of the femoral head into the acetabulum
- may be negative after 2 months of age as soft tissue contractures may develop preventing relocation
- a "click" is usually nonpathological
hip is not painful
widening of the perineum
asymmetry of the folds of the buttocks and thigh (extra skin fold on the medial aspect of the thigh)
uneven knee levels
shortening of the ipsilateral leg
(measure distance from the anterior superior iliac spine to the inferior edge of the medial malleolus)

2. Dislocatable Hip

positive Barlow's Test
- for dislocatable hip
- with the hip flexed and in midabduction, a "clunk" is heard when the leg is displaced laterally (femoral head exiting the acetabulum)
- a "click" is usually nonpathological

2. Toddler

1. Gait Disturbances

1. Bilateral Dysplasia

Duck Waddle Gait (bilateral Trendelenberg Gait)
due to weakness of the hip abductors, the pelvis on the unsupported side descends)

2. Unilateral Dysplasia

painles limp with ipsilateral leg length shortening

2. Associated Symptoms

decreased abduction due to contracture of the iliopsoas and hip adductor muscles
hyperlordosis of the lumbar spine
toe walking

3. Complications

aseptic necrosis of the proximal femur
medial knee joint instability
femoral nerve palsy
failure to achieve concentric reduction
inferior or anterior dislocation or subluxation

INVESTIGATIONS:

1. Imaging Studies

1. Ultrasound

procedure of choice in hospitals with the expertise

2. Skeletal X-Rays

unreliable in the first 6 months of life but reliable afterwards due to ossification of the femoral head
AP view of the hip showing lateral and superior dislocation of the femoral head
may also use Lauenstein (frog) lateral views
complications detected:
- altered shape of the femoral head
- delayed ossification of the femoral nucleus (which usually appears between 3-7 months of age)
- abnormal alignment of the proximal femur and acetabulum
- disrupted Shenton line, acetabular index, quadrant assessment, and/or centre edge angle of Wiberg
- acetabular dysplasia
- increased slope of the acetabular roof
also useful in ruling out congenital anomalies of the proximal femur

3. Others

MRI or CT scans may also be used for difficult cases

MANAGEMENT:

1. Newborn/Infants (0-6 months)

1. Reducable Hip

treat all unstable hips (positive Ortoloni's sign) because even some located hips may retain dysplastic features
goal is to achieve concentric reduction between the femoral head and the acetabulum
no role for triple diapers
use a Pavlik harness
- if unfamiliar with use, refer to a Paediatric Orthopod as the harness must be continually adjusted
- this devise holds the hips in flexion (100-110 degrees) and moderate abduction (50-70 degrees) in an attempt to tighten the hip capsule
- use until the clinical and radiologic or ultrasound examinations are normal (usually about 6-12 weeks)
- contraindications:
  - non-reducable hip
  - significant muscle imbalance (i.e., spina bifida)
  - excessive stiffness
  - excessive ligamentous laxity
  - difficult family circumstances
- complications with incorrect use:
  - inferior hip dislocation
  - femoral nerve and/or brachial plexus palsies
  - skin maceration and breakdown
- effective in:
  - 98% of patients with acetabular dysplasia or hip subluxation
  - 85% of patients with complete dislocations

2. Age 6 to 24 Months

closed or open reduction followed by casting and then an abduction brace

3. Over 2 Years

1. Surgery

open reduction

4. Prognosis

85-95% success rate if detected and treated within the first few weeks of life
important to continually screen high-risk infants after the newborn period:
- see "Etiology (Multifactorial)"
- plagiocephaly
- any significant musculoskeletal anomaly
- any lower limb deformity
  - persistent asymmetric thigh folds
  - metatarsus adductus
  - club foot
- excessive ligamentous laxity

ADDITIONAL REFERENCES:

1. Morcuende, J.A. and S.L. Weinstein. New Developments in Developmental Dysplasia of the Hip; Current Problems in Pediatrics 24(10): 335-343 (1994).