الفهرس 
Introduction and aim of workOnly 14 pages are availabe for public view
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Abstract
Developmental dysplasia of the hip (DDH), formerly known as
congenital dislocation of the hip, comprises a spectrum of
abnormalities that include abnormal acetabular shape (dysplasia)
and malposition of the femoral head, ranging from dislocatable
hip and mild subluxation to fixed dislocation. (Dezateux C et al,
2007).
The origin and pathogenesis of DDH are multifactorial. Abnormal
laxity of the ligaments and hip capsule is seen in patients with
DDH. The maternal hormone relaxin may also be a factor. Causes
of oligohydramnios are thought to be reduced in utero space,
movement restriction, and being a first-born child. Extreme hip
flexion with knee extension, as in the breech position, tends to
promote femoral head dislocation and leads to the shortening and
contracture of the iliopsoas muscle. (Dezateux C et al, 2007).
Delayed diagnosis of mild hip dysplasia is an important cause of
secondary osteoarthritis despite routine screening of infants,
accounting for approximately 25% of all patients requiring total
hip arthroplasty. The radiographic diagnosis of hip dysplasia in
the young adult may be subtle. (Beltran LS et al, 2013).
Radiographs are readily available and relatively low in cost. The
main limitations are radiation exposure and radiography’s inability to demonstrate the cartilaginous femoral head.
Radiographs are of limited value during an infant’s first 3 months
of life, when the femoral heads are composed entirely of cartilage,
but they become more reliable for use in infants 4–6 months of
age, with the appearance of femoral head ossification. (Dezateux
C et al, 2007).
Ultrasonography offers distinct advantages compared
with other imaging techniques:
First, unlike plain radiography, it can distinguish the cartilaginous
components of the acetabulum and the femoral head from other
soft tissue structures.
Second, real-time Ultrasonography permits multiplanar
examinations that can early determine the position of the femoral
head in respect to the acetabulum; thus it provides the same type
of information that can be obtained with arthrography,
computerized tomography, or magnetic resonance imaging, but at
lower cost.
Third, although ultrasonography is more expensive than plain
radiography, it doesn’t require sedation and doesn’t involve
ionizing radiation.
Fourth, unlike other techniques, it allows observation of changes
in hip position with movement (Gerscovich, 2007).
US during an infant’s first 4 weeks of life often reveals the
presence of minor degrees of instability and acetabular
immaturity in a normal hip; however, nearly all of these resolve
on follow-up. To increase the reliability of this test, it is
recommended that US studies be performed when infants are 4–6
weeks of age. (American Academy of Pediatrics. 2000).
US evaluation of the hip is performed using a high-frequency
linear array transducer with either one of the two methods have
emerged: a static acetabular morphology method proposed by
Graf and a dynamic stress technique proposed by Harcke.
(Engesaeter LB et al, 1990).
Dynamic maneuvers are performed similar to the Barlow clinical
examination. The dislocated femoral head will migrate superiorly,
posteriorly and laterally. The Ortolani manoeuver with abduction
and flexion of the femur can also be performed to check for
reducibility of the dislocated hip. (Ladino MF Torres et al,
2009).
Additional features to assess by US include characterizing the
acetabular margin. The normal acetabular margin should be
mildly angulated and sharp. Dysplastic hip tend to have a rounded
or blunt margin. The degree of hip dysplasia corresponds with the
hypertrophy and pulvinar hypertrophy. (Shipman
SA et al, 2006).
MRI provides superior soft-tissue characterization compared with
US. for precisely identifying soft-tissue obstacles that may
interfere with concentric hip reduction. (Jaramillo D et al, 1998).
The utility of MRI is not for diagnosis but for assessing outcome
after treatment in children with DDH after SPICA placement for
closed reduction. (Laor T et al, 2000).
MRI can also be used to evaluate complex hip dislocations, for
presurgical planning, and for evaluation of avascular necrosis.
(Desai AA et al, 2011).
After SPICA placement MRI is used to identify joint congruity in
both the axial and coronal planes, acetabular morphology
(dysplastic vs. nondysplastic), any growth disturbance or
deficiencies of the capital femoral epiphysis, and intrinsic or
extrinsic obstacles to concentric location. Intrinsic obstacles for
reduction include the abnormal shape of the femoral epiphysis
and acetabulum, inverted labrum hypertrophied pulvinar,
ligamentum teres and transverse acetabular ligament.
Summary Chapter 5