Dynamic Ultrasound Technique
Proposed Standard Currently Under Review by the American College
of Radiology - Comments should be directed to Dr. Harcke at (302)
651-4640, phone; (302) 651-4626, fax, Email address: 
tharcke@aidi.nemours.org
D R A F T
ACR STANDARD FOR PERFORMANCE OF
THE INFANT HIP ULTRASOUND EXAMINATION
These standards and guidelines have been developed to assist practitioners
performing ultrasound studies of the infant hip. Adherence to
the following standards will maximize the probability of detecting
most of the abnormalities that relate to hip position, hip stability,
and development of the acetabulum.
INDICATIONS/CONTRAINDICATIONS FOR THE EXAMINATION
Ultrasonography serves as an excellent method for diagnostic imaging
of the immature hip. Sonography affords direct visualization of
the cartilaginous components of the hip joint. The value of ultrasonography
diminishes as development of the ossification center occurs. Between
six months and a year of age, radiography becomes more reliable.
Usually by one year of age the center is sufficiently developed
to prevent good visualization of the acetabulum with ultrasound.
Sonography of the infant hip can be used both in the diagnosis
of developmental dysplasia of the hip (DDH)* and in monitoring
treatment (when performed using customary splint type devices).
Risk factors for DDH include abnormal findings on clinical examination,
family history of DDH, breech presentation at birth, and postural
molding conditions (torticollis, foot deformity). Although females
have a higher prevalence of DDH than males, gender alone is not
considered a risk factor.
*This term has replaced the term congenital dysplasia (dislocation)
of the hip (CDH). (1)
QUALIFICATIONS OF PERSONNEL
See the ACR Standard for Performing and Interpreting Diagnostic
Ultrasound Examinations (1992, Res 9).
EXAMINATION
The diagnostic examination of the infant hip incorporates two
orthogonal views which are adequate in themselves to provide an
assessment of hip position, stability, and morphology when the
study is correctly performed and interpreted. It should be noted
that additional views and maneuvers can be obtained and that these
may enhance the confidence of the examiner.
Examination of the hip to diagnose DDH should include examination
at rest and when stress is applied. Morphology is assessed at
rest. The stress maneuvers follow those prescribed in the clinical
examination of the hip and check hip stability.(1) These attempts
to dislocate the femoral head or reduce a displaced head are analogous
to the Barlow and Ortolani tests used in the clinical examination.(2)
It is important that the infant is relaxed when hips are assessed
for instability. It is acceptable to perform the standard exam
with the infant in a supine or lateral position.
Components of the hip exam:
The diagnostic exam should include a coronal view in the standard
plane at rest and a transverse view of the flexed hip with and
without stress.
- Coronal view:
- The coronal view in the standard plane at rest can be performed
with the hip in either the neutral or flexed position. Femoral
head position and displacement is noted. Acetabular morphology
is assessed in this view. Validation by measurement is optional.
Performance of stress in this view is optional.
The following views are illustrated:
- Transverse flexion view:
- Definition of Terms:
- I. Femoral Position
- Neutral: The femoral shaft is in the position of rest,
usually 15-20 degrees of hip flexion.
- Flexed: The femoral shaft is flexed 90 degrees at the
hip.
- II. Imaging Planes and Views
- Coronal Plane: This is an anatomic term defining the
usual anatomic plane through the body which is approximately parallel
to the posterior skin surface of an infant.
- Coronal View in the Standard Plane: This is an ultrasound
view of the infant hip obtained with the transducer in a slightly
oblique CORONAL plane. An image obtained with the transducer in
the anatomic coronal plane will result in a curved appearance
of the iliac bone superior to the acetabulum. For standardization
and reproducibility, a straight or nearly straight appearance
of the ilium is desirable. If the superior edge of the transducer
is rotated 10-15 degrees (usually posteriorly) into an oblique
coronal plane, the ilium will appear straight, and after adjustment
to assure that the imaging plane is through the deepest part of
the acetabulum, the resulting image will be a coronal image in
the standard plane. Since the femoral head is almost spherical,
the position of the femur is unimportant in this view, but the
view is most easily obtained with the femur in neutral.
- Transverse Plane: This is the anatomic Transverse or
axial plane (similar to the plane of a primary CT image)
- Transverse View: This is the ultrasound view obtained
when the femur is in flexion and the transducer is in the transverse
plane. The transducer is posterolateral so that imaging can be
accomplished while the hip is abducted and adducted. The hip should
be evaluated with the femur in flexion at rest and during application
of posteriorly directed force (stress, see #3) to assess stability.
- III. Stress
- Stress is the controlled application of force to the femoral
shaft to assess instability of the hip. Posteriorly directed stress
with the femur in 90 degrees of flexion and maximum ADDuction
is known as the Barlow maneuver (2). A number of other maneuvers,
have been described and can be used during ultrasound examination,
but these are optional.
Modification of the diagnostic examination
Examination of the hip during treatment for DDH may be modified
according to requirements of the treatment protocol. Abduction
splints are commonly used to restore stability and foster acetabular
development. The stress portion of the exam is not performed during
treatment unless requested by the treating physician. The examination
in splint should address hip position in the device (to include
changes occurring with passive range of motion allowed by the
device) and acetabular development.
Assessment for acetabular dysplasia can be a specifically requested
indication. This might be requested in an infant who has no risk
factors, no prior indication of instability or who has been treated
or observed and achieved stability. In such cases, a coronal view
in the standard plane (see above) can be performed. Note: If abnormality
is identified on an initial assessment for acetabular dysplasia,
a complete diagnostic examination is recommended.
- EQUIPMENT
- Infant hip sonography should be conducted with a real-time
scanner, a linear array transducer is preferred; however, it is
possible to use sector or curved linear transducers. [Caution:
Measurements of acetabular morphology should only be made on images
produced with a linear transducer. (4)] The highest frequency
transducer which is able to provide sufficient depth to image
the medial aspect of the acetabulum should be used. A 5.0 MHz
or higher frequency is best suited for infants less than six months
of age. A lower frequency transducer may be required in some older
infants.
- EQUIPMENT QUALITY CONTROL
- Each facility should have documented policies and procedures
for monitoring and evaluating the effective management, safety,
and proper performance of imaging equipment. The quality control
program should be designed to minimize patient exposure, personnel
and public risks and maximize the quality of the diagnostic information.
At least annually, equipment performance should be monitored in
accordance with manufacturers' specifications.
- QUALITY IMPROVEMENT
- Procedures should be systematically monitored and evaluated
as part of the overall improvement program of the facility. Monitoring
should include the evaluation of the accuracy of interpretations
as well as the appropriateness of the examination.
Data should be recorded and periodically reviewed in order to
compare the accuracy with information obtained from other evaluations.
This analysis should attempt to identify opportunities for use
of ultrasound to improve patient care. The data should be collected
in the manner which complies with statutory and regulatory peer
review procedures in order to protect the confidentiality of the
peer review data.
- DOCUMENTATION
- Adequate documentation is essential for high quality in patient
care. There should be a permanent record of the ultrasound examination
and its interpretation. Comparison with prior relevant imaging
studies is recommended when these are available. Images can be
recorded in any of the standard storage formats. When optional
measurements are performed, it is essential that they are obtained
from images which meet the criteria for a standard plane. Images
should be labeled with the examination date, patient identification,
hip being imaged, and image orientation. A report of the ultrasound
findings should be included in the patient's medical record, regardless
of where the study is performed. Retention of the ultrasound examination
should be consistent both with clinical needs and with relevant
legal and local health care facility requirements.
- REFERENCES
- Aronsson DD, Goldberg MJ, Kling TF, Roy DR: Developmental
dysplasia of the hip. Pediatrics 94:201-208, 1994.
- Barlow TG: Early diagnosis and treatment of Congenital dislocation
of the hip. J Bone Joint Surg [Br] 44-B:292-301, 1962.
- Graf R, Tschauner C, Klapsch W: Progress in prevention of
late developmental dislocation of the hip by sonographic newborn
hip "screening": Results of a comparative follow-up
study. J Pediatr Orthop Part B 2:115-121, 1993.
- Graf R: Hip sonography-How reliable? Sector scanning versus
linear scanning? Dynamic versus static examination? Clin Orthop
and Related Research 18-21, 1991.
- Grissom LE, Harcke HT, Kumar SJ, Bassett GS, MacEwen GD: Ultrasound
evaluation of hip position in the Pavlik harness. J Ultrasound
Med 7:1-6, 1933.
- Hangen DH, Kasser JR, Emans JB, Millis MB: The Pavlik harness
and developmental dysplasia of the hip: Has ultrasound changed
treatment patterns? J Pediatr Orthop 15:729-735, 1995.
- Harcke HT, Grissom LE: Performing dynamic sonography of the
infant hip AJR 155:837-844, 1990
- Harcke HT: The role of ultrasound in the diagnosis and management
of developmental dysplasia of the hip (DDH). Pediatric Radiology
25:225-227, 1995.
- Keller MS, Weltin GG, Rattner Z, Taylor KJW, Rosenfield NS:
Normal instability of the hip in the neonate: US Standards. Radiology
169:733-736, 1988.
- Rosendahl K, Markestad T, Lie RT: Ultrasound screening for
developmental dysplasia of the hip in the neonate: The effect
on treatment rate and late cases. Pediatrics 94:47-52, 1994.
- Rosendahl K, Aslaksen A, Lie RT, Markestad T: Reliability
of ultrasound in the early diagnosis of developmental dysplasia
of the hip. Pediatr Radiol 25:219-224, 1995.
- Zieger M, Schulz RD: Ultrasonography of the infant hip, III:
Clinical application. Pediatr Radiol 17:226-232, 1987.
- H. Theodore Harcke, M.D.
Department of Medical Imaging
Alfred I. duPont Institute
P.O. Box 269
Wilmington, Delaware 19899
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