Pediatric Hip

...on transverse views the femoral head sits within the "_____" formed by the _____ ________ and the ______

-"U" -femoral metaphysis and ischium

Sonographic evaluation should be delayed until at least _____-______ of age because of what

-3-4 weeks -physiologic laxity often present in newborns

screening at ____-_____ of age is recommended, and sonographic evaluation is practical up to 6 months of age (prior to what?)

-4-6 weeks -ossification of the femoral head

Describe type 4

-dysplastic acetabulum with α angle less than 43 degrees, -lateral and cephalad displacement of the femoral head -and fibrofatty pulvinar interposed between the femoral head and acetabulum.

_______ _____ and ________ is important for normal hip development

-early diagnosis -treatment

The femoral head is contiguous with the _______, which is contiguous with the what....?

-neck -diaphysis or shaft of the femur.

DDH incidence is approximately ______ in ________ w/a ______ female to male ratio

1.5 in 1000 4.5:1

Application of stress is omitted when hips are being examined in a ____ _____ or ______ _______ unless otherwise requested by the orthopedic surgeon

Pavlik harness or splint device

How is the transducer held during the dynamic technique?

When the left hip is examined, the transducer is held in the right hand and the left hand is used to manipulate the infant's leg. When the right hip is examined, the transducer is held in the left hand and the infant's leg is manipulated with the right hand.

What is the triradiate cartilage?

Y-shaped cartilage connecting the ilium, ischium, and pubis

The standard plane is defined by identifying what?

a straight iliac line, the tip of the acetabular labrum, and the transition from the os ilium to the triradiate cartilage

in coronal views the femoral head approximately half of the diameter lies on either side of the _________

ilium (echogenic line)

What are the hip bones? Convergence of the bones creates the concave hip socket

ilium, ischium, and pubis

the hip bone or coxal bone is composed of what

ilium, ischium, and pubis.

DDH is a spectrum of abnormalities ranging from what?

mild acetabular dysplasia and reducible subluxation to irreducible subluxation or dislocation of the femoral head

The coronal view in the standard plane can be obtained with the hip in the physiologic _______ position (15°-20° flexion) or in the flexed position

neutral

The femoral head and the acetabulum must articulate with each other for what?

normal hip development.

Describe type 1

normal, α angle greater than 60 degrees

The anatomic coronal plane is approximately ________ to the posterior skin surface of an infant

parallel

what is the metaphysis

portion of the femur just distal to the femoral head

what is the femoral head

proximal, rounded portion of the femur that sits within the acetabulum

What is the sonographic appearance of the triradiate cartilage

hypoechoic

-Normal alpha angle is what? -and the normal beta angle is what? (as one gets bigger, the other gets smaller).

-60 degrees or greater - 55 or less

Explain what is obtained and imaged during a graf technique

-A coronal neutral image is obtained. -The femoral head can the identified sitting in the acetabulum. -The iliac line will be identified superiorly, and bony shaft of the femoral neck will be identified inferiorly. -The iliac line should appear as a straight line, which is important in making an accurate assessment.

Both hips should be examined. The diagnostic examination for DDH incorporates 2 orthogonal planes which are

-a coronal view in the standard plane at rest -and a transverse view of the flexed hip with and without stress.

The ____________ is located at the lateral aspect of these bones and is joined by a growth plate, the ________ __________.

-acetabulum -triradiate cartilage

With the graf technique the 1st line is...

-aligned with ilium and extends through the head of the femur

What would the clinical diagnosis of DDH consists of

-asymmetric skin folds -limited abduction of the hip -abnormal barlow or ortolani maneuver

The femoral head is __________ at birth, and the acetabulum is composed of ________ and ________.

-cartilaginous -cartilage and bone

Sonography is the study of choice for evaluating suspected DDH, the ability to demonstrate what make it superior to X-ray

-cartilaginous and soft tissue components of the hip joint

what are the sonographic methods for evaluating the hip

-dynamic stress technique -static graf technique -static technique to asess femoral head coverage

What are the risk factors for DDH

-family history -intrauterine breech postion

The fibrocartilaginous labrum, which extends ________ to cover the femoral head, is _________ to the cartilaginous head

-laterally -hyperechoic

DDH is believed to be due to abnormal______ ______ (rather than structural abnormality), which is accentuated by what?

-ligamentous laxity -excessive levels of circulating maternal estrogens

In addition, during fetal development, ________ _________ __________ contribute to the laxity of fetal ligaments, which may in turn create a vulnerable atmosphere for the hip to become __________ or dislocatable.

-maternal hormonal influences -subluxable

...... It is also because of the large cartilaginous component of the hip that it is subject to _________, with normal development depending on the femur being in good contact within the __________.

-molding -acetabulum

.....This enables an assessment of hip position, stability, and morphology when the study is correctly performed and interpreted. If position, stability, and/or morphology cannot be assessed when attempting to perform a complete examination, the report should....... and it is acceptable to....

-note the portion not done. -It is acceptable to perform the examination with the infant in a supine or a lateral decubitus position.

Morphology is assessed at ________. The stress maneuver (posterior push maneuver) is performed to evaluate for hip instability with the hip and knee _____ and the thigh _______ (Barlow maneuver).

-rest -flexed -adducted

...The infant is maintained in this position for ______ ________ until what happens?

-several weeks -the hip joint capsule tightens and the acetabulum matures

Describe type 3

-shallow acetabulum with decreased α angle less than 43 degrees, -femoral head minimally covered and subluxed laterally -labrum everted -and pulvinar deep in the acetabulum

Eventually, in chronic subluxation or dislocation what happens

-the joint capsule is stretched -the acetabulum fills with fibrofatty tissue (pulvinar) -and the labrum inverts.

With the graf technique, the beta angle is formed between the _______ and _______ lines

1st and 2nd

With the graf technqiue the alpha angle is formed between the ______ and _______ lines

1st and 3rd

The femoral head begins to ossify from the center outward at what age?

2-8 months of age

The femoral head ossification center develops between the ________ and ________ months of life

2-8th

femoral head coverage should be _______ or greater

50%

The acetabulum-to-femoral head relationship usually becomes normal within _______ to ______ weeks of treatment.

6 to 8 weeks

what transducer do we use while evaluating the neonatal hip

7.5 MHz or higher linear array transducer

with the transverse flexion view the examination is performed with the hip flexed at _______

90°

What are the four hip types by the graf technique

Type 1-4

what is the sonographic appearance of the femoral head

hypoechoic with scattered internal echoes; central echogenic area will be seen with ossification

If the femoral head is subluxated, subluxable, dislocated, or dislocatable, reducibility can be assessed by doing what

abducting and externally rotating the hip (Ortolani maneuver).

At the rim of the acetabulum sits a lip of cartilage called the _________ __________.

acetabular labrum.

Femoral head fits firmly in the _________ under normal conditions

acetabulum

The femoral head and the acetabulum must ______ with each other for normal hip development.

articulate

What is the hip joint

ball-and-socket joint; articulation of the femur with the pelvis

why are neutral views and stress maneuvers not performed post treatment

because they would require removal of the harness or abduction splint

The 3rd line extends from the what to the what?

bony edge of the acetabulum at the triradiate cartilage to the lowest point of the ilium.

Hip bones are made up more _______ than ______at birth

cartilage than bone

sonographically at birth, the femoral head is __________ and _________ to bone

cartilaginous and hypoechoic

What is the sonographic appearance of the acetabulum

cartilaginous portions appear hypoechoic and bony portions appear echogenic with posterior shadowing

.... and the beta angle is defined as the

cartilaginous roof of the acetabulum.

If the dislocation is reduced, the femoral head should be in the....

center of the acetabulum.

developmental dysplasia of the hip (DDH) is formerly referred to as

congenital hip dislocation

what is the hip bone also called

coxal bone

...these do what?

direct the femoral head toward the triradiate cartilage, stimulating normal acetabular development.

The smaller the alpha angle and the larger the beta angle, the more likely what?

dysplasia is present

Abnormal development of the acetabulum can result in developmental what?

dysplasia of the hip

What is the sonographic appearance of the hip bones

echogenic linear structures with posterior shadowing

The 2nd line....

extends from ilium along the labrum

The dislocated femoral head also presses on the chondro-osseous pelvis, producing a what?

false acetabulum (pseudoacetabulum)

what happens with the femoral head during subluxation

femoral head lies partially within and partially outside the acetabulum

What happens with the femoral head during dislocatable

femoral head lies within the acetabulum but can be moved out of the acetabulum

....This creates an articulation point for the_________

femur

What is the acetabular labrum

fibrocartilaginous rim around the margin of the acetabulum

Hip dysplasia in the neonate is usually treated with a

flexion-abduction-external rotation harness (most commonly the Pavlik harness) or splint,

.....The ossified parts of the acetabulum appear as.....

highly reflective linear or curvilinear structures.

The femoral head is _________ in shape and sits in the ________

rounded acetabulum

What is the acetabulum

rounded cavity (socket) that the femoral head (ball) sits in; located at the lateral aspect of the hip bones

If the hip subluxes or dislocates, the acetabulum becomes what....? because it lacks the stimulus of the femoral head for development.

shallow and steep rather than cup-shaped

Describe type 2

slightly shallow acetabulum with decreased α angle between 44 and 59 degrees.

With the graf technique, the alpha angle is defined as the....

the bony or osseous roof of the acetabulum,

what allows for sonographic evaluation of the hip in infants?

the cartilaginous characteristics

what is the proximal portion of the femur called

the femoral head

what happens with the femoral head during dislocation

the femoral head does not rest in the acetabulum

what happens with the femoral head during subluxable

the femoral head lies within the acetabulum but can be moved within the acetabulum

If the superior edge of the transducer is rotated 10° to 15° (usually posteriorly) into an oblique coronal plane, what will happen?

the ilium will appear straight

What are the bones of the hip joint composed of

the pelvic girdle and the femur

what is sonography used to determine with the pediatric hip

the position of the femoral head within the acetabulum and the stability of the femoral head.

In the posttreatment evaluation, sonographic images are acquired only in _______ and ________ views

transverse/flexion and transverse/coronal

what is the sonographic appearance of the acetabular labrum

triangular structure located in between femoral head and acetabulum; hyperechoic to cartilage

....After adjustment to ensure that the imaging plane is through the deepest part of the acetabulum (which includes visualization of the________ ______ and ________ ________), the resulting image will be a coronal view in the standard plane.

triradiate cartilage and the ischium posteriorly

Positioning of the femoral head laterally, superiorly, or posteriorly indicates ________ _______

unsatisfactory reduction

what is the galeazzi or alis test

•Assesses relative shortness of the femur/unevenness between the knees with the hips and knees flexed and feet flat •If one knee is lower than the other, there may be a dislocated hip on the lower side •Used for infants 3 months and older

What is the Ortolani maneuver?

•Assesses the reduction of a dislocated hip •Hip is flexed 90 degrees and abducted into a frogleg position •Movement of the femoral head over the posterior labrum back into the acetabulum produces a palpable "clunk" that can be felt by the examiner

What is the Barlow maneuver?

•Attempts to dislocate the femoral head •Hip is flexed and adducted and the knee is pushed posteriorly and superiorly •Exit of the femoral head over the posterior labrum produces a palpable "clunk" that can be felt by the examiner

What does the static graf technique

•Scanning performed with infant in the lateral decubitus position and the femur extended •Transducer is positioned laterally in a coronal plane •Alpha and beta angles are obtained •Diagnosis of DDH is based on abnormal alpha and beta angles

what does the dynamic stress technique consists of

•scanning performed with infant supine and transducer positioned over the lateral or posterolateral aspect of the hip •Coronal and transverse images of the hip obtained in both extension (neutral position) and flexion •With the hip flexed, the femur is adducted and the Barlow maneuver is performed •Diagnosis of DDH is based on an abnormal position of the femoral head at rest or with stress