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Yeo Ryang Kang , Joonbum Koo. Abstract Ultrasonography US is a useful screening method for the diagnosis of developmental dysplasia of the hip DDH and congenital spinal anomalies in infants. Introduction Developmental dysplasia of the hip DDH is one of the most common causes of disability among children. DDH encompasses a wide variety of pathologic conditions, ranging from fine acetabular dysplasia to irreducible hip dislocation. The previous term congenital dysplasia of the hip has been replaced by developmental dysplasia of the hip, because many of the clinical manifestations of DDH may not be detectable at birth, but are recognized at a later age [ 1 ].
The incidence of DDH ranges from 1. Multiple risk factors have been described, including breech positioning in utero , being the first-born child, oligohydramnios, family history, female sex, and deformities postural or structural of the foot and torticollis. In addition, increased joint laxity in the setting of exposure to maternal estrogens during the perinatal period may play a role in the development of DDH, and the left hip is more frequently affected than the right [ 2 , 3 ].
Ultrasonography US is the preferred modality for evaluating the hip in infants aged less than 6 months. US enables dynamic evaluation of the hip with stress maneuvering, as well as direct imaging of the cartilaginous portions of the hip that cannot be seen on plain radiographs [ 4 ]. Hip US has become the most commonly used diagnostic tool for DDH during early infancy because the early and accurate diagnosis of DDH is the most important factor contributing to appropriate treatment [ 5 ]. Additionally, US can thoroughly characterize nearly all spinal anomalies during the first days of life.
To understand spinal anomalies, a knowledge of embryonic development is necessary. Starting on the 17th day of gestation, the neural plate thickens bilaterally to form the neural folds. During normal development, the neural folds close in toward the midline to form the neural tube. Premature disjunction of the neural ectoderm from the cutaneous ectoderm results in the development of spinal dysraphism, which is defined as incomplete or absent fusion of the midline neural, mesenchymal, and cutaneous structures and can be classified into three categories: As the ultrasound beam passes through predominantly cartilaginous and incompletely ossified spinal arches in newborns and infants, US can be used to investigate both the spinal canal and cord.
Progressive ossification of the posterior elements of the vertebrae hinders satisfactory examinations in older children [ 6 ]. This article describes the anatomy of the normal infant hip joint, procedural details for performing US, landmarks, the classification of US results, the measuring technique, and the US appearance of transient synovitis in older children. Furthermore, we describe the technique for performing spinal US in newborns, the anatomy of the normal infant spine, normal variants, and congenital spinal anomalies.
If the well-established techniques for examination, interpretation, and measurement are meticulously followed, it is easy to manage newborn hip problems via this method [ 5 ]. To perform hip US, the hip joints must be evaluated in the standard coronal plane with a linear array probe [ 8 ]. Before evaluation of the hip joint, it is essential to identify the chondroosseous junction.
This is because the echo of the chondro-osseous junction is an important landmark used to identify the femoral neck and other anatomical landmarks: The ultrasound transducer is then placed in the anatomic coronal plane Fig. Next, the transducer is moved backwards and forwards from the basic position to identify the round structure of the hip joint. If a sonogram contains a straight iliac wing contour, triradiate cartilage, and an apparent acetabular labrum, this indicates that it has a standard plane Fig. However, in dislocated hips, lateral and posterior displacement of the femoral head prevents visualization of the femoral head and the center of the acetabulum in the standard plane.
Therefore, if the displaced femoral head is followed, the ultrasound plane is no longer in the standard plane. The direction of displacement of the femoral head means that it is usually the posterior sectional plane that is visible Fig. The femoral shaft is seen anteriorly, terminating in the femoral head, which rests on the ischium Fig. To identify a dislocatable hip, the transducer is placed in a posterolateral position during the Ortolani and Barlow maneuvers.
If the relationship between the posterior acetabulum and the femoral head changes with gentle stress, the hip is unstable [ 9 ]. DDH results in a shallow acetabulum and decreased coverage of the femoral head [ 2 , 8 ]. These patients require no treatment, although there is a small risk of delayed DDH. Follow-up at the age of 3 months is recommended to confirm normal development [ 4 ]. The purpose of the harness is to maintain the hip in a flexed and abducted position in order to bring the femoral head as close to the acetabular ring as possible [ 1 ].
Between 6 months and 2 years of age, closed reduction and casting is attempted under general anesthesia to maintain the femoral head in the proper position without damaging it. Arthrography is a useful tool to evaluate the success of the reduction. The cast is applied to the reduced hip for a period of approximately 12 weeks.
If closed reduction cannot be accomplished at this stage, open reduction may be necessary [ 1 ]. Open reduction is usually required above the age of 2 years, mostly by femoral osteotomy to relieve pressure over the femoral head and to reshape the acetabulum.
The patient is usually immobilized in a spica cast for weeks [ 1 ]. Ultrasound for Transient Synovitis of the Hip and Septic Arthritis in Children Transient Synovitis Transient synovitis of the hip is the most common cause of acute hip pain and limping. It typically occurs in children aged years with localized pain in the groin region, anterior thigh, or medial knee [ 10 ]. Because the imaging results are similar to those of other causes of acute hip pain in children, the diagnosis is essentially made by exclusion.
Sonography of baby hips for the diagnosis of DDH and dysplasia has grown steadily in importance in recent years. A strict standardized technique for investigation of the baby and interpretation of the sonograms has made hip ultrasound reproducible, reliable and independent of. Hip Sonography: Diagnosis and Management of Infant Hip Dysplasia: Medicine & Health Science Books @ www.farmersmarketmusic.com
The main differential diagnoses are septic arthritis [ 11 ] and juvenile rheumatoid arthritis [ 10 ]. Ultrasound Examination Hip US must be performed in the neutral position hip extended with slight external rotation using an anterior approach in the parasagittal plane along the long axis of the femoral neck.
It may be useful to compare the resulting image with that of the contralateral normal hip Fig. On US examination, joint effusion can be seen between the anterior and posterior layers of the anterior joint capsule Fig. In children, the distance between the outer margin of the hip capsule and the surface of the femoral neck should not be greater than 5 mm, or more than 2 mm thicker than the contralateral normal side [ 13 ]. Septic Arthritis Septic arthritis typically affects the hip, knee, shoulder, elbow, and ankle. Staphylococcus aureus is the most common causative organism. In neonates, group B streptococci and coliform bacteria were previously common causative organisms.
In children aged from 3 months to 5 years, Haemophilus influenzae is an important cause, but the incidence has declined considerably due to the use of vaccinations. US of septic arthritis shows hypoechoic joint fluid with or without echogenic debris in patients with clinical signs of joint infection. US can be used for the guided aspiration of joint fluid for the early diagnosis and treatment of septic arthritis [ 13 , 14 ]. Additionally, power Doppler may show increased capsular vascularity [ 15 ].
The vertebral level is usually determined by counting up from the L5-S1 junction. Generally, the infant is examined in the prone position [ 7 , 16 ]. There are two main indications for lumbar spinal US in infants.
Spinal US is used to evaluate midline cutaneous malformations of the back, such as dimples, as well as hemangiomatous or hairy lesions associated with dysraphic anomalies of the spinal cord. Spinal US is also used to determine the reason for the failure of a lumbar puncture and the location from which cerebrospinal fluid CSF may be tapped [ 17 ]. Normal Anatomy The longitudinal scan shows a hypoechoic tubular spinal cord with an echogenic central echo complex Fig. On histologic analysis, the central canal corresponds to the border between the myelinated ventral white commissure and the central portion of the anterior median fissure.
In healthy newborns, the central canal is not filled with CSF but is instead overgrown with glial fibrils [ 6 ]. The caudal end of the spinal cord corresponds to the conus medullaris, which continues into the filum terminale Fig. In healthy newborns, the tip of the conus medullaris is no lower than the top of L3 in a term infant Video clip 1 , or the bottom of L3 in a preterm infant [ 19 ].
The filum terminale appears as a thin cord-like echogenic structure, forming a parallel line extending from the conus medullaris. The filum terminale is surrounded by the nerve roots of the cauda equina, and it is sometimes difficult to differentiate the filum terminale from the nerve roots [ 6 ].
An axial scan of the spinal cord shows a hypoechoic spinal cord with an echogenic central echo complex and paired dorsal and ventral nerve roots within the anechoic subarachnoid space Fig. Normal Variants Several common normal variants that may be confused with certain disorders on lumbar spine US are discussed below, including transient dilatation of the central canal, ventriculus terminalis, prominent filum terminale, filar cysts, cauda equina pseudomasses, and pseudosinus tract [ 6 ]. Transient dilatation of the central canal In newborns, a slight dilatation of the central canal of the spinal cord may be detected Fig.
This is viewed as an incidental finding in healthy newborns and almost disappears during the first weeks of postnatal life [ 6 ]. Ventriculus terminalis The ventriculus terminalis is a small, ependyma-lined, oval, cystic structure positioned at the distal cord Fig.
This structure extends over mm and has a transverse diameter of mm. The ventriculus terminalis develops during embryogenesis due to incomplete fetal regression of the embryonic terminal ventricle during the first weeks after birth in the conus medullaris. This variant causes no clinical symptoms [ 6 ]. Prominent filum terminale If the filum terminale is observed to be particularly echogenic in comparison with other nerve roots Fig.
It can be distinguished as normal variants by a typical midline course and a thickness of less than 2 mm [ 7 ]. Filar cysts A filar cyst is located in the filum terminale and has a fusiform shape and the well-defined, hypoechoic appearance of a simple cyst Fig. A filar cyst is distinguished from the ventriculus medullaris by its location just below the conus medullaris.
It is a normal variant and has no known clinical significance. Therefore, a filar cyst does not require additional imaging [ 7 ]. Pseudomass due to positional nerve root clumping When a newborn is scanned in the decubitus position, positional clumping of the nerve roots can occur Fig. However, such masses disappear when the child changes to the prone position [ 7 ]. Pseudosinus tract The pseudosinus tract is seen on US as a residual cord-like region composed of fibrous tissue extending from a skin dimple to the coccyx Fig.
True dermal sinus tracts do not occur at the tip of the coccyx but are typically found in a more cranial location. However, careful evaluation should be performed for any fluid or mass along the course of the fibrous tract. If CSF is found to be draining via a dimple, further evaluation is necessary using other imaging modalities, such as magnetic resonance imaging, because it is more likely to be a true sinus tract [ 7 ].
Congenital Spinal Anomalies Congenital spinal dysraphisms can be classified into two categories on the basis of the absence or presence of a soft-tissue mass and skin covering. Those without a mass include spinal lipoma, tethered cord, diastematomyelia, and anterior sacral meningocele. Lipomyelomeningocele and myelocystocele are skin-covered soft-tissue masses. Myelomeningocele and myelocele show a mass located on the back but are without a skin covering [ 6 , 20 ].
Tethered cord Tethered cord is caused by the incomplete involution of the terminal spinal cord. Using real-time US, a low-lying conus below the L2-L3 disk space with an absence of normal nerve root motion can be diagnosed as a tethered cord Fig. Traction on the abnormally anchored filum terminale and adjacent nerve roots can initiate clinical symptoms at any age, such as difficulties in ambulation, weakness, abnormal reflexes, stiffness, bladder dysfunction, and, less often, bowel dysfunction. Other associated spinal findings include a thickened filum terminale, spinal dysraphism, congenital spinal lipomas or dermoids, syringomyelia, scoliosis, myelocele, and dermal sinus tracts.
Other non-neurologic anomalies, including tracheoesophageal fistula, VATER syndrome, and congenital heart disease, are also commonly associated with tethered cord [ 20 ]. Spinal lipoma Spinal lipomas are composed of normal fat that may change in size with increased weight and tend to grow significantly during the first year of life. Spinal lipomas appear on ultrasound as an echogenic intraspinal mass adjacent to the deformed spinal cord.
They may be intradural, extradural, or a combination thereof. Eighty-four percent of lipomas contain not only fat but also neural tissue or meninges. Treatment consists of resection, when possible, or debulking [ 6 , 20 ]. Myelocele and myelomeningocele During embryogenesis, the dorsally localized failure of fusion of the neural folds leads to myelocele and myelomeningocele. Severe neurologic disturbances, mainly of the lower extremities such as paresis or paralysis and bladder or bowel dysfunction , can occur in patients with myelocele and myelomeningocele, as well as secondary hydrocephalus after repair [ 6 ].
The purpose of spinal US in patients with myelocele or myelomeningocele is the recognition of associated malformations. These malformations consist of tethering of the spinal cord, diastematomyelia, hydromyelia or syringomyelia, Chiari II syndrome, and arachnoid cysts [ 6 ]. Dorsal dermal sinus A dorsal dermal sinus is observed as an epithelium-lined tract between the skin and the spinal cord, cauda equina, or arachnoid.
Dorsal dermal sinus is caused by incomplete separation of the superficial ectoderm from the neural ectoderm at a circumscribed point. The bony acetabular roof is less well-formed and there is a rounded acetabular bony rim. Here a type IIc hip. The bony acetabular roof is severely deficient with a rounded to almost flat bony rim. The alpha angle is 46 degrees. A type D hip is much like a type IIC hip, but the main difference is a decentring hip with a displaced cartilage roof. In Graf type IV there is a severe dislocation of the femoral head which obscures most of the bony roof.
The labrum is dislocated downwards and interposed between the femoral head and the lateral acetabular edge. Clubfoot was thought to be a risk factor, but this no longer holds true. Ultrasound orientation With ultrasound we are looking at the same anatomic structures as on the x-ray. And this is the way the ultrasound image is displayed on the screen of the ultrasound machine. Examination technique A lineair, high frequency probe is used.
The focus is set at the acetabular edge. This is shown in the video. Sometimes in very displastic hips the use of a convex transducer can be of help. Measurements Measurements First three points of interest need to be indentified in the image: When the bony rim is angular this point is easily recognized.
When rounded this point is defined as the point where the concavity of the bony acetabular roof changes into the convexity of the ilium. In this video you'll see proper measurement after placement of the three points of interest. This is the Graf classification - short version. This is the Graf classification - long version. At the age of 3 months the decision has to be made whether the hip is normal or not.
Type I Type I hips have an alpha angle of more than 60 degrees and are normal. Type Ia This examination shows a good morphology of the bony acetabular roof with a sharp angular bony rim. There is nice coverage of the femoral head by the cartilaginous roof and the labrum.
The alpha angle is above the 60 degrees and the beta-angle is way below 55 degrees. Type Ib This is also a normal hip. These hips are normal and follow up is not needed. Type II Type IIa If a child is less than 3 months old, then an alpha angle of degrees is considered an immature hip.
The age of the child is 4 weeks, so we call this a type IIa. The femoral head is still covered by the cartilaginous roof and the labrum. Type D A type D hip is much like a type IIC hip, but the main difference is a decentring hip with a displaced cartilage roof. The labrum is moved upwards. The cartilaginous roof is compressed between the femoral head and the bony acetabular rim.
Reporting In the table a list of things that should be mentioned in your report.