Infant and Pediatric Hip Sonography

Flashcards covering neonatal and pediatric hip anatomy, ultrasound scanning techniques, DDH risk factors, clinical maneuvers, Graf classifications, and joint effusions.

What are the primary clinical indications for performing a sonogram on a neonatal hip?

To rule out developmental displacement of the hip, joint effusion and/or septic arthritis, and proximal focal femoral deficiency.

Which three bones fuse together to form the pelvic girdle?

The ilium, ischium, and pubis.

How do the pelvic bones and the femoral shaft appear sonographically at birth?

They are ossified and appear hyperechoic with acoustic shadowing.

What is the location and sonographic appearance of the triradiate cartilage in a neonate?

It lies posterior to the femoral head and appears hypoechoic.

When does central ossification of the femoral head typically begin, and in which gender does it occur earlier?

It typically begins between $3$ and $8\text{ months}$ of age (as early as $4\text{ weeks}$) and often occurs earlier in girls than in boys.

Approximately how much of the femoral head should be covered by the acetabular labrum?

Approximately two thirds of the femoral head.

Which artery branch is contained within the ligamentum teres in young children, and by what age does it usually disintegrate?

It contains a branch of the obturator artery, which usually disintegrates by $7\text{ years}$ of age.

Which ligament is one of the strongest in the body and connects the anterior inferior iliac spine to the intertrochanteric line?

The iliofemoral ligament.

Which muscles serve as the primary flexors of the hip joint?

The psoas major, iliacus, and rectus femoris muscles.

What is the maximum limit of normal hip extension, and which muscles bring it about?

Extension is limited to $20\text{ degrees}$ and is brought about by the hamstrings and gluteus maximus.

What is the reported incidence of developmental displacement of the hip (DDH) per live births?

Between $1.5$ and $20$ cases per $1000$ live births.

What key risk factors are associated with developmental displacement of the hip (DDH)?

Breech positioning, female gender ($2.5$ times more common than males), left hip involvement ($64\text{\%}$), unilateral occurrence ($64\text{\%}$), firstborn children, and a family history of DDH.

What clinical examination sign is indicated by a lower knee position on the affected side when the patient is supine with flexed knees?

The Galeazzi sign.

What linear-array transducer frequency ranges are recommended for neonatal hip ultrasound across different age groups?

$12\text{--}15\text{ MHz}$ for premature infants, $7.5\text{--}9\text{ MHz}$ for average weight neonates up to $3\text{ months}$, $5.0\text{--}7.5\text{ MHz}$ for infants $3$ to $7\text{ months}$, and $3\text{ MHz}$ after $7\text{ months}$.

How is ambidextrous scanning performed during a bilateral neonatal hip ultrasound?

The right hip is examined with the transducer held in the sonographer's left hand, and the left hip is examined with the transducer held in the right hand.

What visual landmark pattern describes a normal hip in the coronal/flexion view?

A "ball on a spoon" appearance, where the femoral head represents the ball, the acetabulum forms the spoon, and the iliac line forms the handle.

What geometric configuration is produced by a normal hip joint in the transverse view at rest or in abduction?

A "U" configuration.

What are the clinical objectives of the Barlow maneuver and the Ortolani maneuver?

The Barlow maneuver assesses if the hip can be dislocated using adduction, whereas the Ortolani maneuver determines if a dislocated femoral head can be reduced back into the acetabulum using abduction.

What Graf alpha angle measurement defines a normal infant hip?

An alpha angle of $>60\text{ degrees}$.

How are Graf Types I, II, III, and IV classified?

Type I is normal, Type II is immature or delayed development, Type III is dysplasia, and Type IV is frank dislocation with severe acetabular dysplasia.

What are the static femoral head coverage percentage cutoffs for normal hips, subluxation, and dislocation?

Mean coverage is $54\text{--}56\text{\%}$ (lower limit $45\text{\%}$ to $50\text{\%}$), subluxation occurs below $39\text{\%}$, and dislocation is less than $10\text{\%}$.

How is a subluxable hip defined under stress testing in the dynamic Harcke technique?

The proximal femur moves more than $6\text{ mm}$ on the left and $4\text{ mm}$ on the right within the acetabulum, but cannot be displaced out of it.

What specific anatomical positioning is maintained by a Pavlik harness during treatment for DDH?

The hip is positioned in flexion, abduction, and external rotation.

What procedure is performed under sonographic guidance when a hip joint effusion is identified?

Arthrocentesis to aspirate the synovial fluid.