• The disorder of developmental dysplasia of the hip (Incidence 1 – 2 per 1000 live births) is a spectrum from the congenitally detectable dislocated hip to a shallow acetabulum that may cause the hip to lateralise with development.
• The Ortolani and Barlow manoeuvres are a mandatory component of the Department of Health neonatal examination. The sensitivity of these tests in experienced hands are between 0.5 – 0.7 within the literature.
• The developing femoral ossific nucleus radiographically appears between 4 – 6 months and is eccentrically placed within the head. Children > 6 months should have a plain radiograph for diagnosis.
• It is controversial whether an USS based screening programme should exist to aid in the earlier diagnosis of DDH. The current NIPE (NHS neonatal and infant physical examination programme) guidelines advocate a selective screening programme based on the risk factors:

1. Breech in the third trimester and
2. First degree family history.

Infant hip ultrasound has been popularized since the early 1980’s. The evolution of the technique was driven by the lack of sensitivity of plain radiographs to determine the position of the immature unossified femoral head.

Two popularized sonographic methods include:

Graf Method (Stolzalpe, Austria)

Harcke Method (Dupont, US)

Both have their limitations, however the Graf technique can be used to quantify the dysplasia.

AP plain radiograph demonstrating bilateral dislocated hips. Hilgenreiner (a line drawn horizontally through the superior aspect of both triradiate cartilages) and Perkins line (a line drawn perpendicular to intersecting the lateral most aspect of the acetabular roof) have been drawn demonstrating that the metaphysis lies out of the inferomedial quadrant.

The presence of the ossific nucleus.

The child is placed in either the lateral or supine position and a linear probe is used to generate the image. Once the ossific nucleus is formed this blocks the identification of structures medial to it and accurate USS is then difficult. The child should then have ongoing evaluation with plain radiographs.

The Graf Technique relies on a quality image being generated in the standard plane so that reproducible measurements (α and β angles) can be used to quantify the bony and cartilaginous roofs, These values can be used to classify the severity of the hip dysplasia and comparisons made over time to evaluate the progression of the dysplastic joint.

A neonatal hip ultrasound, using the Graf technique.

Hip ultrasound demonstrating the anatomical structures;

1. Chondro-osseous border
2. Femoral head
3. Synovial fold
4. Capsule
5. Labrum
6. Cartilage roof
7. Bony roof
8. Bony rim

1.    Chondro-osseous border

This is the junction between the osseous metaphysis and the cartilaginous femoral neck.

2.    Femoral head

The immature cartilaginous head (black) contains echoes (white), these are vascular lakes or sinusoids.

3.    Synovial fold

This is the point of reflection of the capsule off the femoral neck.

4.    Capsule

This continues upwards to insert into the perichondrium of the iliac bone.

5.    Labrum

This is the bright triangular echo of fibrocartilage that lies beneath the capsule adjacent to the femoral head.

6.    Cartilage roof

The hyaline cartilage roof is attached to the bony roof of the acetabulum. It appears black as if there is an echo gap.

7.    Bony roof

The bony acetabular roof should cover more than 50% of the femoral head.

8.    Bony rim

This is the most lateral part of the concavity of the bony socket, where it changes to the convexity of the iliac bone.

The standard plane ensures that the coronal image is taken through the absolute centre of the acetabulum without any tilting errors. This allows consistency between scans for comparison and accurate measurements.

1.    Lower limb

This cuts through the central depth of the acetabular fossa.

2.    Plane

A vertical line tangential to the iliac bone demonstrates the mid portion of the acetabulum.

3.    The labrum

Measurement of the a and b angles.

The base line (Line 1) starts from the uppermost point of the proximal perichondrium and is drawn caudally tangential to the iliac bone. The bony roof line (Line 2) starts from the inferior border of the lower limb and is drawn tangential to the bony roof. The cartilage roof line (Line 3) is drawn between the bony rim and the centre of the labrum. The a angle is between lines 1. And 2. The b angle is measured between lines 1. And 3.

This demonstrates a Type I hip.

• This is a normal mature hip joint.
• The roof coverage is good.
• The bony rim may be angular or slightly blunted.
• The hyaline cartilage covers the femoral head.
• Alpha angle > 60 degrees
• The Beta angle is a research measurement to look at over/ under coverage of the hyaline cartilage roof.

The Harcke method is based on 2 orthogonal planes: a coronal view in the standard plane at rest and a transverse view of the flexed hip with and without stress. There is no requirement to measure alpha and beta angles.

Coronal view of the hip joint in the standard plane with the hip in the physiologic neutral position (usually 15°–20° of hip flexion). (Image taken from AIUM practice guidelines 2013)

Coronal anatomic illustration.

• Ac  acetabular cartilage
• C, capsule
• GT,greater trochanter
• H, cartilaginous femoral head
• IL, ilium
• L, labrum
• LT/P, ligamentum teres/pulvinar complex
• M, femoral metaphysis
• Tr, triradiate cartilage

Coronal ultrasound image. (Image taken from AIUM practice guidelines 2013)

Anatomic structures:

• C capsule
• G, gluteus muscles
• H, cartilaginous femoral head
• IL, ilium
• IS, ischium
• TR, triradiate cartilage
• GT, greater trochanter
• L labrum

Transverse view of the hip, with the hip and knee flexed to 90° (Image taken from AIUM practice guidelines 2013)

Transverse anatomic illustration.

• Ac acetabular cartilage
• G, gluteus muscles
• GT, greater trochanter
• H, cartilaginous femoral head
• Is, ischium
• L, labrum
• LT/P, ligamentum teres/pulvinar complex
• M, femoral metaphysis
• Pu,pubis
• Tr, triradiate cartilage.

Transverse ultrasound image. (Image taken from AIUM practice guidelines 2013)

• G gluteus muscles
• H, cartilaginous femoral head
• IS, ischium
• L, labrum
• M, femoral metaphysis
• FS, femoral shaft.