Hip dysplasia imaging .

The presentation explains the different theories of DDH and the proper imaging ultrasound technique.

1. Dr/Ahmed Bahnassy
Consultant Radiologist
Riyadh Military hospital

2. What is DDH
•The natural history of DDH dictates that
this is not necessarily a simple task.
•DDH is composed of two elements:
•(1) instability and
•(2) abnormal morphology.

3. Assesment
•The technique for performing an infant hip
sonogram may vary depending upon one's belief
as to pathophysiology.
•Initial focus of hip sonography by Graf was on
acetabular morphology, using a single static
sonographic view.
•Harcke et al, on the other hand, emphasized
assessment of instability in addition to
morphology and advocated a dynamic
sonographic technique.

4. •The current recommendation for
sonographic examination of the infant hip
incorporates assessment of both instability
and morphology so the pathophysiology
issue is resolved with respect to
performance of the sonographic
examination .

5. Hip sonography
TABLE 1 -- HIP SONOGRAPHY FOR DEVELOPMENTAL DYSPLASIA OF THE HIP
View Key Feature Comment
Coronal neutral*
A Acetabular morphology Measurement optional
Coronal flexion
A Acetabular morphology Measurement optional
Stability (if stressed) Stress optional
Used with Pavlik harness
Transverse flexion
A Stability Stress required (except during treatment)
Used with Pavlik harness
Transverse neutral Femoral head position Optional view
Data from Harcke HT, Grissom LE: Performing dynamic sonography of the infant hip. AJR Am J Roentgenol 155:837-844, 1990;
with permission.

6. Correct coronal view

7. Correct transverse view

8. I-Morphological assesment
•This system is based upon the
appearance of the acetabulum in a
coronal neutral position and describes
measurement of acetabular slope (alpha
angle) and position of the acetabular
labrum (beta angle).

9. Benefits
•It is a well-recognized feature of DDH that
the condition changes with time.
•It is greater at birth and decrease
spontaneously in the first few months of
life without treatment.

10. •Of particular relevance is the distinction of
normal and abnormal in the first few
weeks of life. It is recognized that a large
number of newborns have a mild instability
that has been described as physiologic
laxity. In association with this is mild
acetabular dysplasia consisting of a
slightly increased angulation of the bony
acetabulum as determined by Graf alpha
angles (type 2A).

11. How to make good
exam
•The proper coronal view, whether the femur is in
neutral or in flexion, contains three elements .
• (1) The echoes from the bony ilium should be in
a straight line parallel to the surface of the
transducer.
•(2) The transition from the os ilium to the
triradiate cartilage must be seen definitively.
•(3) Finally, the echogenic tip of the cartilage
labrum needs to be present in the same plane
that contains the other two elements.

12. Model view

13. Take your measurements

15. •Graf classification of infant hips based on the depth and shape
of the acetabulum as seen on coronal ultrasonograms.
•Type I: normal; characterized by a well-formed acetabular cup
with the femoral head beneath the acetabular roof.
•Type II: immature in infants less than three months of age and
mildly dysplastic in infants older than three months;
characterized by a shallow acetabulum with a rounded rim.
•Type III: subluxated; characterized by a very shallow
acetabulum with some displacement of the femoral head.
•Type IV: dislocated; characterized by a flat acetabular cup and
loss of contact with the femoral head.

16. Angle values

17. Type III
•Lateral
displacement
of femoral
head.
•Soft tissue
between
femoral
haead and
acetabulum

18. Type IV

19. II- Stability assesment
•The assessment of instability incorporates
dynamic technique in two views that
include application of stress.
•Both views are performed with the hip
flexed: the transducer orientation is
coronal for one view and axial for the
other.

20. Relax your patient
•Assessing the hip when the infant is not
relaxed masks the presence of instability.
•To ensure a cooperative infant, it is
recommended that a sonogram be
performed in a quiet, semidarkened
environment with a parent present and
visible to the child.
•Bottle feeding the infant during the
examination is helpful.

21. •Examination by ultrasound is modeled
after the clinical examination and is based
upon the provocative test for dislocation of
an unstable hip (Barlow test) or the
reduction of a dislocated hip (Ortolani
test).

22. •With subluxation and lesser degrees of
instability, the flexed hip tends to seat with
abduction.
•Displacement is noted during adduction
and stress.

23. •The key feature of instability is the lateral
movement (toward the transducer) of the
femoral head along the ischium. This results in
increased echogenic soft tissue medially.
•Whereas a normal hip shows slight changes in
the appearance of the medial tissues between
abduction and adduction, with instability, the
thickness more than doubles

24. Dynamic testing
•At rest :Normal.
•With stress
subluxation occurs
and B angle
increases.

25. Summary
•Ultrasonic evaluation of DDH includes:
•I-Morphology assesment (Graf angles)
•II-Stability assesment (dynamic exam )
•Acquired data depend on proper
technique.