Diagnostic ultrasound ( PDFDrive )

1932 PART V Pediatric Sonography
A
B
FIG. 55.6 Atypical Hip. (A) Radiograph of a 4-month-old infant with Kniest dysplasia shows shortening of the long bones and bulbous ends
of the bones. (B) Coronal/neutral sonogram shows increased echogenicity of the cartilage and coxa vara with elevation of the greater trochanter
(arrow) and narrowing of the acoustic window of the hip joint. h, Femoral head; L, lateral; S, superior.
Sot tissue swelling and other sot tissue abnormalities outside
the joint capsule have also been diagnosed.
Teratologic Hip Dislocation
Teratologic hip dislocation is considered a diferent entity from
DDH. Teratologic hips are dislocated earlier in utero than DDH
and are seen in patients with various syndromes and neuromuscular
diseases such as arthrogryposis, Larsen syndrome, and
chromosomal abnormalities. Sonographic examination is the
same as for DDH, but the planes of interrogation may require
adjustment if there are contractures. Sonographic indings at
rest resemble frank dislocation in DDH, but teratologic dislocation
is more severe with contractures and limited movement. he
acetabulum is small, typically obscured by the proximal femur,
and the femoral head is distorted from chronic dislocation. 58,59
Atypical Hips
Other patients with “atypical hips” include those with skeletal
dysplasias, congenital myopathy, or congenital coxa vara. hese
patients have displacement of the hips, acetabular dysplasia, and
coxa vara. here is delayed ossiication of the bones, allowing
examination at a later age, but the cartilage and sot tissues oten
show abnormal increased echogenicity, which obscures the osseous
anatomy. With coxa vara, there is narrowing of the sonographic
window, and the cartilage of the greater trochanter is elevated.
he greater trochanter can be mistaken for a dislocated femoral
head, so careful scanning is required. Adduction of the femur
during scanning can widen the sonographic window and allow
visualization of the normally located femoral head 60-63 (e.g., Kniest
dysplasia) (Fig. 55.6).
Congenital Foot Deformities
Club Foot
he treatment of equinovarus deformity has dramatically
improved with the development of the Ponseti technique of serial
casting followed by limited surgery when necessary, 64 and similar
changes have occurred with treatment of vertical talus. Imaging
of foot anomalies has traditionally been radiographic, but
ultrasound is now recognized as an accurate alternative for
examination of both unossiied and ossiied tarsal bones at rest
and with movement to assess alignment before and ater
treatment.
In clubfoot, there is medial displacement of the navicular and
anterior displacement of the medial malleolus in relation to the
talus with narrowing of the space between the bones. 65 he most
commonly used sonographic measurement is the distance between
the medial malleolus and the navicular (MMN), measured at
rest and with abduction in the medial coronal plane. he measurement
is lower than normal in clubfoot, and there is decreased
movement with abduction. Other views and measurements include
the calcaneocuboid (CC) joint, the length of the talus (TL), the
talonavicular joint, the posterior sagittal view for measurement
of the tibiocalcaneal distance, and the navicular morphology. 66-69
Normal measurements have been established for some of the
views (MMN, CC, TL) for comparison. 70
Vertical Talus
Congenital vertical talus is a less common anomaly of the foot,
frequently occurring in patients with neuromuscular or genetic
abnormalities in which there is dorsal dislocation of the navicular