health& medicine

1. Radiological Imaging of Developmental dysplasia of the hip.
Dr/ ABD ALLAH NAZEER. MD.

2. Developmental dysplasia of the hip joints:
Developmental dysplasia of the hip (DDH) denotes aberrant
development of the hip joint and results from an abnormal relationship
of the femoral head to the acetabulum. There is a clear female
predominance, and it usually occurs from ligamentous laxity and
abnormal position in utero. Therefore, it is more common
with oligohydramniotic pregnancies. This article describes the
commonly used radiographic measurements and lines involved in DDH.
Epidemiology
The reported incidence varies between 1.5 and 20 per 1000 births, with
the majority (60-80%) of abnormal hips resolving spontaneously within
2-8 weeks 1 (so-called immature hip).
Risk factors include :
female gender (M:F ratio ~1:8)
family history
breech presentation
oligohydramnios

3. Clinical presentation
DDH is usually suspected in the early neonatal period due to the
widespread adoption of clinical examination (including Ortolani test,
Barlow manoeuvres, Galeazzi sign). The diagnosis is then usually
confirmed with ultrasound, although the role of ultrasound in screening is
controversial.
Radiographic features
Ultrasound is the modality of choice prior to ossification of the proximal
femoral epiphysis. Once there is a significant ossification then x-ray
examination is required.
For some reason, the left hip is said to be more frequently affected. One-
third of cases is affected bilaterally .
Ultrasound
Ultrasound is the test of choice in the infant (<6 months) as the proximal
femoral epiphysis has not yet significantly ossified. Additionally, it has the
advantage of being a real-time dynamic examination allowing the stability
of the hip to be assessed with stress views.
Some values are used to 'objectively' assess morphology.

4. Alpha angle
The alpha angle is formed by the acetabular roof to the vertical
cortex of the ilium. This is a similar measurement as that of the
acetabular angle (see below). The normal value is greater than or
equal to 60º.
Beta angle
The beta angle is formed by the vertical cortex of the ilium and the
triangular labral fibrocartilage (echogenic triangle). The normal value
is less than 77º but is only useful in assessing immature hips when
combined with the alpha angle (see the sonographic classification of
developmental hip dysplasia).
Bony coverage
The percentage of the femoral epiphysis covered by the acetabular
roof. A value of >50% is considered normal
US criteria for DDH.
1. < 50% coverage of the capital femoral epiphysis.
2. Alpha angle < 60 degrees.
3. Blunted acetabular margin.

5. Plain radiograph
The key to plain film assessment is looking for symmetry and
defining the relationship of the proximal femur to the developing
pelvis. The ossification of the superior femoral epiphyses should
be symmetric. Delay of ossification is a sign of DDH.
Hilgenreiner line
Hilgenreiner line is drawn horizontally through the superior
aspect of both triradiate cartilages. It should be horizontal but is
mainly used as a reference for Perkin line and measurement of
the acetabular angle.
Perkin line
Perkin line is drawn perpendicular to Hilgenreiner line,
intersecting the lateral most aspect of the acetabular roof. The
upper femoral epiphysis should be seen in the inferomedial
quadrant (i.e. below Hilgenreiner line, and medial to Perkin line).

6. Acetabular angle
The acetabular angle is formed by the intersection
between a line drawn tangential to the acetabular
roof and Hilgenreiner line, forming an acute angle. It
should be approximately 30 degrees at birth and
progressively reduce with the maturation of the joint.
Shenton line
Shenton line is drawn along the inferior border of the
superior pubic ramus and should continue laterally
along the inferomedial aspect of the proximal femur
as a smooth line. If there is a superolateral migration
of the proximal femur due to DDH then this line will be
discontinuous.

13. Normal and dysplastic hips. A, Anteroposterior radiographs of right hip with graphic representations
in 29-year-old woman (A) with normal acetabular roof with weight bearing forces applied over entire
surface and 24-year-old woman (B) with dysplastic shallow acetabular roof with weight bearing forces
distributed over smaller area. Arrows indicate acetabular roof and arcs indicate weight bearing forces.

14. Ultrasound is the reference standard for evaluating the hip in an
infant before 6 months, when capital femoral epiphyseal ossification
usually occurs. It is a nonionizing, quick, and portable examination
that furthermore offers the advantage of dynamic imaging in
addition to standard static views.
The American College of Radiology recommends that a standard
ultrasound examination be performed in two orthogonal planes:
a coronal view in the standard plane at rest and a transverse view
of the flexed hip with and without stress. Three anatomic landmarks
—ilial line, triradiate cartilage, and labrum—are used to measure
the α and β angles. A standard plane includes a straight iliac line,
the femoral head with maximum diameter, the tip of the echogenic
acetabular labrum, and the triradiate cartilage. shows the anatomic
landmarks in a normal hip. Meticulous scrutiny of the α angle
measurement is necessary because false-positive findings can occur
if the imaging plane is suboptimal. When reporting the α angle, the
largest angle, not the average angle, should be given.

15. A, Standard static coronal (A) and transverse (B) ultrasound
images of normal hip. Glut = gluteal muscles, Ac = acetabular
cartilage, LTP = ligamentum teres/pulvinar complex, FH =
cartilaginous femoral head, Tr = triradiate cartilage.
B, Standard static coronal (A) and transverse (B) ultrasound
images of normal hip. Glut = gluteal muscles, Ac = acetabular
cartilage, LTP = ligamentum teres/pulvinar complex, FH =
cartilaginous femoral head, Tr = triradiate cartilage.

16. A, Ultrasound image shows measurement of α angle (thin
diagonal line) in normal hip in 1-month-old boy, which is more
than 60°; β angle (thick line) is also within normal range.
B, Ultrasound image in 1-month-old girl with developmental
dysplasia of hip shows α angle (dashed line) is abnormal,
measuring 43°. Acetabulum is shallow and femoral head is
laterally dislocated. There is pulvinar fat hypertrophy (arrowhead)
and blunting of bony acetabulum (thick solid arrow).

17. Real-time coronal sonogram of the hip shows calculation of the acetabular
alpha angle. An angle of 60° or greater indicates acetabular maturity.

18. Real-time coronal sonogram of the hip with calculation of the
d/D ratio. Coverage of 58% or greater is considered normal

22. Radiography:After the child is 4–5 months old, the ossification of the femoral epiphysis
begins to obscure sonographic landmarks and radiography becomes more reliable for detection of
DDH. This is the standard tool to diagnose DDH after 6 months. An anteroposterior radiograph of
the hips in neutral position is used to assess the morphology of the acetabulum, ossification of the
femoral head, and position of the femoral head relative to the acetabulum. In early infancy, a
normal acetabulum is relatively steeper and straighter. The morphology of the acetabulum changes
with age, with the acetabulum becoming more curved inferiorly along the medial and lateral
margins. shows the spectrum of normal hips in anteroposterior radiographs in a 6-month-old child
and a 2-year-old child, respectively. In DDH, there is delayed ossification of the femoral head and
an abnormally shallow acetabulum, thereby predisposing to subluxation and dislocation.
Additionally, late complications, such as osteoarthritis and avascular necrosis, can occur. A frog-leg
lateral view is sometimes used to determine whether a subluxed hip reduces. Several lines and
angles are used to diagnose and further characterize DDH: The first is the Hilgenreiner line, which
is a line crossing through both tri-radiate cartilages. The second is the acetabular angle, which is
formed by the Hilgenreiner line and a line drawn through the acetabular roof. A neonate should
normally have an acetabular angle of less than 30°. The acetabular angle should be less than 22°
at and beyond 1 year of age. Acetabular morphology and the degree of femoral head ossification
changes with age. The third is the Perkins line, which is a vertical line drawn perpendicular to the
Hilgenreiner line and intersecting the lateral rim of the acetabular roof. A normally situated
femoral head is in the inferior medial quadrant. The fourth is the Shenton line, which is a C-shaped
line drawn along the inferior border of the superior pubic ramus and the inferomedial border of the
femoral neck. A normal Shenton line should form a smooth arc. The fifth is the anterior center-edge
angle, which is an angle subtended by a craniocaudal line through the center of the ossified
femoral head and a line from the center of the femoral head to the lateral margin of the acetabular
roof. A center edge angle less than 20° is indicative of dysplasia.

23. A, Normal anteroposterior radiograph of hips in 6-month-old
boy shows acetabular angles in right and left hip (lines) are
normal for age, measuring 22° and 24°, respectively.
B, Normal anteroposterior radiograph of hips in 2-year-old boy shows α angles
of right and left hips are normal for age, measuring 18° and 20°, respectively.
Note how contour of acetabula changes with age. Ossified femoral epiphyses
are symmetric and well seated within acetabula. Hilgenreiner (long-dashed line),
Perkins (short-dashed line), and Shenton (dotted line) lines are superimposed.
Femoral epiphysis is appropriately situated in inferomedial quadrant. Center
edge angle is formed by vertical line through center of femoral head and line
from center to lateral acetabular roof (solid lines).

24. A, Anteroposterior radiograph obtained at 6
months of age shows shallow left acetabulum
with steep roof, compatible with DDH.
B, Anteroposterior radiograph obtained at 1 year of age
shows interval growth of left femoral epiphysis; however,
it remains smaller relative to right femoral epiphysis. Left
acetabular dysplasia persists.

25. A, Initial radiograph shows superolateral subluxation of right
femoral head, valgus deformity, and acetabular dysplasia.
B, Postoperative radiograph after iliac osteotomy
and femoral varus osteotomy shows interval healing
and improved acetabular roof coverage of femoral
head. Previous valgus deformity has been corrected.

26. Frontal radiograph of the pelvis in a 1-year-old child with a dislocated right hip. The degree of
ossification of the femoral head on the dislocated side is decreased compared with that of the
normally located left hip. The abnormally located hip articulates with a false neoacetabulum.

27. Frontal radiograph of the pelvis obtained with the legs in the frog-leg
position indicates that the plane of the femoral projection is toward
the triradiate cartilage, suggesting that the hips are reducible.

28. Healed Salter Osteotomy After three years16M/F

29. 10-week-old female, bilateral DDH.

30. Bilateral Hip Dislocation.

31. Arthrography is typically performed intraoperatively by the orthopedic
surgeon at the time of reduction. Obstacles to successful reduction, such
as limbus eversion, can be identified. Arthrography during
reconstructive osteotomy helps obtain concentric reduction of the hip.
Fluoroscopic image from arthrography in 15-month-old girl with left developmental dysplasia
of hip shows contrast material within joint. Femoral head is seated in dysplastic acetabulum.

32. Arthrogram of congenital hip dysplasia. (A) Arthrogram of the right hip in the neutral position in a 1-year-old girl with
congenital subluxation of the hip shows the typical displacement of the hip lateral to, but below the acetabular labrum.
There is accumulation of contrast agent in the stretched capsule (arrow), and the ligamentum teres is elongated. (B) In
the frog-lateral position, the head moves more deeply into the acetabulum, but subluxation is still present.

33. Arthrogram of congenital hip dislocation. (A) Anteroposterior radiograph of the right hip in an 8-year-old girl
demonstrates complete superolateral dislocation of the femoral head. Note the shallow acetabulum. (B) Arthrogram of
the hip shows a deformed cartilaginous limbus and stretching of the ligamentum teres. The femoral head lies superior
and lateral to the edge of the cartilaginous labrum. Note the accumulation of contrast agent in the loose joint capsule.

34. CT is generally reserved for problem solving in difficult cases and involves a low-dose technique, often
in the setting of prior postoperative evaluation. The CT technique at our institution is weight based
(Table 4). CT is more commonly used postoperatively after the patient has been placed in a cast to
define the success of reduction. Postoperatively, concentric reduction of the femoral head can be
confirmed. Preoperative assessment includes evaluation of bony acetabular morphology and the
ossified femoral epiphysis as well as the femoral head position relative to the acetabulum.
A, Preoperative radiograph showing left DDH.
B, Postoperative CT image was obtained to evaluate
relocation of left hip after iliac and femoral varus osteotomy.

36. CT of congenital hip dislocation. Axial section through the proximal femora and hips of a
6-month-old boy shows posterolateral dislocation of the left hip. The right hip is normal.

37. Treatment of congenital hip dysplasia. (A) Anteroposterior radiograph of the pelvis in a 1-year-old boy demonstrates
the typical appearance of congenital dislocation of the left hip. (B) After conservative treatment with a Pavlik
harness at age 2, there is still subluxation. Note the broken Shenton-Menard arc. At age 3, after further conservative
treatment by skin traction and application of a spica cast, there is almost complete reduction of subluxation, as
demonstrated by contrast arthrography (C). (D) CT scan, however, demonstrates some minimal residual lateral
displacement of the femoral head, as evidenced by the medial accumulation of contrast.

38. Mild right hip dysplasia. AP pelvic view shows lateral CE angle measuring less than 20º (lateral CE angle = 19º,
considered diagnostic of hip dysplasia); and axial CT image shows deficient anterior, posterior and global
acetabular coverage with decreased AASA, PASA and HASA (AASA = 46º , PASA = 87º ad HASA = 133º).

39. MRI Findings of the Normal Hip Familiarity with the normal appearance of the pediatric
hip on MRI is critical to detect pathology. The ossified and unossified femoral heads,
cartilage, and ligaments are clearly depicted. The infantile acetabulum can be categorized
into three basic components: bony, cartilaginous, and ligamentous or soft tissue. The bony
acetabulum is seen on radiography and is composed of the acetabular parts of the ilium,
ischium, and pubis, all of which are held together by the triradiate cartilage. The
cartilaginous acetabulum consists of the hyaline cartilage at the articular surface, which is
U-shaped and is bridged by the transverse acetabular ligament, and the supporting
vascularized growth cartilage, which includes the triradiate cartilage. The labrum, trans-
verse acetabular ligament, and the ligamentum teres are the primary ligamentous
structures. The labrum is of low to intermediate signal intensity and appears as a small
triangular structure along the edge of the acetabulum on axial images. The labrum's
intrinsic signal intensity typically increases slightly from T1- to T2-weighted images. It is
important to evaluate for normal morphology and position of the labrum when evaluating
dysplastic hips. The transverse ace-tabular ligament is located inferiorly, where there is a
deficiency of cartilaginous acetabulum. The ligamentum teres originates from the
transverse ligament and inserts on the femoral head fovea. The iliopsoas tendon is a low-
signal-intensity structure that is seen just anteromedial to the anterior labrum on the axial
plane. The intraarticular fat pad, or pulvinar, lies in the central portion of the acetabulum
and has the highest signal intensity of all the structures in the hip, paralleling that of
subcutaneous fat. It is important to assess for pulvinar hypertrophic changes, which can
serve as an obstacle to successful reduction. The pulvinar in the affected hip can be
compared with the contra lateral side to determine any relative size asymmetry.

40. The ossified femoral epiphysis appears as a low-signal-intensity
structure within the high-signal-intensity unossified hyaline cartilage.
Symmetry between the two ossified femoral heads should be noted.
When evaluating for concentric femoral head positioning, a line can
be drawn through both triradiate cartilages. After successful
reduction, the ossified portion of the femoral epiphyses should lie
anterior to this line. The ossified portions of the anterior and posterior
columns are low to intermediate in signal intensity, with an interposed
band of high-signal-intensity triradiate cartilage. Depending on the
degree of acetabular dysplasia, the unossified parts of the anterior
and posterior columns affect acetabular depth. The fibrous joint
capsule attaches to the acetabular margin peripheral to the labrum.
At birth, the femoral attachment is near the metaphysis and migrates
inferiorly as the hip develops. By 12 months of age, the capsule is partly
fused to the femoral neck periosteum and runs up the femoral neck,
attaching to the edge of the cartilaginous femoral head. Normal
acetabular development is dependent on concentric positioning of the
femoral head within the acetabulum.

41. MRI Findings of Developmental Dysplasia of the Hip When characterizing DDH
using MRI, the dysplastic acetabulum should be evaluated for retroversion and degree
of femoral head coverage. There may be associated cartilaginous defects or
delamination. Delayed ossification of the femoral head can be determined by
comparing the ossific nucleus of the femoral head in the affected hip with the contra-
lateral side. A major advantage of MRI is the ability to visualize the cartilaginous
acetabulum and determine its contribution to femoral head coverage. MRI depicts the
unossified acetabular epiphysis in the ilium and underlying labrum, therefore showing
greater and more accurate acetabular coverage than that seen on radiography alone.
Recent orthopedic articles have described the utility of bony and cartilaginous
acetabular indexes on MRI in the evaluation of DDH. The bony acetabular index can be
measured by MRI using an anteroposterior coronal view and is similar to the
acetabular index measured on radiography. To obtain the bony acetabular index, the
Hilgenreiner line and Perkins line are drawn using the same landmarks as used on
radiography. The bony acetabular index line is drawn from the Hilgenreiner line at the
lateral part of the triradiate cartilage to the Perkins line at the lateral aspect of the
bony acetabulum. The angle subtended by the bony acetabular index line and the
Hilgenreiner line is the bony acetabular index angle. The cartilaginous acetabular
index is measured by drawing a line from the lateral part of the triradiate cartilage at
the Hilgenreiner line to the lateral acetabular cartilaginous margin (the cartilaginous
acetabular index line). The cartilaginous acetabular index angle is formed by the
cartilaginous acetabular index line and the Hilgenreiner line.

42. A, Anteroposterior radiograph shows lateral
dislocation of right hip. Right acetabulum is steep and
shallow. Right femoral head ossification is delayed.
B, MRI was performed immediately after right hip arthrogram, closed reduction, and adductor
release. Axial T1-weighted images show interval reduction of right hip with mild persistent
posterior subluxation. Acetabulum is shallow. Compared with normal left side (solid arrow, C),
right femoral head ossification is delayed (long solid arrow, B). Anterior labrum is mildly
inverted (short solid arrow, B). Significant pulvinar hypertrophy (dotted arrow
D, Radiograph obtained 6 months after surgery shows interval
improvement with mild persistent subluxation of right hip. However,
right acetabulum is still dysplastic with abnormal acetabular angle.
Right acetabular angle measures 34° and left acetabular angle is 23°.
C, MRI was performed immediately after right hip arthrogram, closed reduction, and adductor
release. Axial T1-weighted images show interval reduction of right hip with mild persistent
posterior subluxation. Acetabulum is shallow. Compared with normal left side (solid arrow, C),
right femoral head ossification is delayed (long solid arrow, B). Anterior labrum is mildly
inverted (short solid arrow, B). Significant pulvinar hypertrophy (dotted arrow, B).

43. T1-weighted images with fat saturation show superimposed bony acetabular index angle (I) and cartilaginous acetabular index
angle (J). Bony acetabular index measures 39.6°, which is fairly concordant with 34° acetabular angle measured on radiographs.
Hypertrophic acetabular cartilage contributes to 15° cartilaginous acetabular index, which is still abnormal but relatively closer
to normal range (mean cartilaginous acetabular index in 2-year-old is 8.2 ± 1.9 [40]) compared with measured bony acetabular
index. This examination served as guide for further orthopedic management. Compared with radiographs, femoral head appears
more concentrically located in acetabulum. Surgeon subsequently elected to treat more conservatively.

44. A, Anteroposterior radiograph shows
shallow steep dysplastic left acetabulum
(long arrow), lateral subluxation of left
hip, and delayed ossification of left
femoral head (short arrow). Radiopaque
objects seen at bottom of image are
buttons overlying patient.
B, Axial T2-weighted image with fat saturation
obtained after interval reduction and with spica cast in
place shows mild residual subluxation of left femur and
fibrofatty pulvinar hypertrophy with small effusion.
Note signal intensity loss of fibrofatty pulvinar with fat
saturation (long arrow). Anterior labrum is inverted
(short arrow). Right hip appears normal with normal-
sized spherical femoral head compared with small and
aspherical left femoral head.
C, Coronal T1-weighted image
shows lateral subluxation of left
femoral head and fibrofatty
pulvinar hypertrophy (arrow). Note
delayed ossification and aspherical
shape of left femoral head.

50. Thank You.