ultrasound to rule out hip dysplasia from a history of a breech ... What is the diagnosis ... Teratologic; caused by a congenital or developmental anomaly. ⢠Torticollis: a condition in which the head tilts to one side ... can develop normally, avoiding possible surgery and .... because a minimal shift in the image may lead to.
HIP DYSPLASIA PROF.DR. SYED AMIR GILANI MBBS,DMRD(Pak)MPH(Pak) PhD(Public Health),PhD(Ultrasound)
CLINICAL SCENARIO • A 4-week-old female infant is seen for a hip ultrasound to rule out hip dysplasia from a history of a breech presentation in utero. The ultrasound of the left hip reveals the finding in. What is the diagnosis and what is the possible treatment, if any, for this infant?
Coronal/neutral view of hip shows relationship of femoral head to acetabulum.
OBJECTIVES • • Identify the normal anatomy of infant hips. • • List the risk factors associated with infant hip
dysplasia. • • Describe the clinical maneuvers used in evaluation for hip dysplasia. • • Describe the sonographic protocol for imaging of infant hips. • • Differentiate hip laxity, subluxation, and dislocation.
GLOSSARY OF TERMS • Abduction: the act of moving an extremity away from •
• • •
•
the body Adduction: the act of moving an extremity towards the body Oligohydramnios: a decreased amount of amniotic fluid that may restrict fetal movement Primigravida: first pregnancy Teratologic; caused by a congenital or developmental anomaly Torticollis: a condition in which the head tilts to one side because of abnormal contraction of the muscles
Normal hip anatomy.
• Every newborn examination includes an
evaluation of the infant's hips for assessment for developmental dysplasia of the hip (DDH). This chapter explores the risk factors for DDH and the clinical examination that may be used to identify DDH. The various modes of testing, including ultrasonography, are examined, in addition to the types of treatment available on the basis of the severity of the disease. The sonographic evaluation of infant hips also includes a review of normal hip anatomy and imaging protocol for evaluation of DDH.
ANATOMY OF THE HIP • The hip forms from the embryonic mesoderm
and is comprised of the femoral head and the acetabulum. The femoral head is cartilaginous at birth and begins to ossify between 2 and 8 months, with ossification occurring earlier in females.1 The acetabulum is comprised of cartilage and bone. The bony acetabulum consists of the ilium, the ischium, and the pubis, which is joined by a growth plate known as the triradiate cartilage. The cartilaginous labrum is located at the acetabular rim and extends over the superolateral aspect of the femoral head.
ANATOMY OF THE HIP • At birth, the hip has a large cartilaginous
component and the femoral head is more shallow in its relationship to the acetabulum. The hip its therefore subject to molding, especially in the first 6 weeks of life. The normal development of the hip is contingent on the femur having adequate contact with the acetabulum without an abnormal amount of stress. When the femoral head is subluxed or dislocated for a significant amount of time, the acetabulum becomes increasingly dysplastic, the femoral head becomes deformed, and the supporting ligaments also deform.
ANATOMY OF THE HIP • The purpose of early treatment of abnormal hips is to
position the hip so that the femoral head and acetabulum can develop normally, avoiding possible surgery and disability. Clinical evaluation and identification of risk factors can be used to identify those infants at risk for development of hip dysplasia. Ultrasound evaluation can be used to further define those infants who will benefit from treatment and to follow their progress. Screening for hip dysplasia is usually reserved for those infants with an abnormal clinical examination or for those infants with identified risk factors to avoid over-treatment of infants with physiologic laxity.
DEVELOPMENTAL DYSPLASIA OF THE HIP • Developmental dysplasia of the hip describes a
spectrum of abnormalities that involve an abnormal relationship of the femoral head to the acetabulum, which includes mild instability, subluxation, and frank dislocation. DDH has also been referred to as congenital hip dysplasia, although this is a misnomer because hip dysplasia may develop after birth. The overall incidence rate of DDH is 0.6:1000 newboms, but significant geographic variability exists.
• Hip instability is associated with joint laxity and may be
identified in newboms affected by maternal hormones. This laxity often resolves within the first few weeks of birth and necessitates no treatment. Subluxation of the hip refers to a femoral head that is shallow in location, allowing it to glide within the confines of the acetabulum. Hip dislocation is defined as a femoral head that is located outside of the acetabulum and maybe reducible or irreducible. Hip dislocation can also be associated with congenital neurologic or musculoskeletal anomalies, including spina bifida, arthrogryposis, and numerous syndromes, and is referred to as teratologic hips.
Risk Factors • Many of the risk factors associated with DDH
are related to the inability of the fetus or newborn to move freely. These conditions include pregnancies affected by oligohydramnios (including serious renal anomalies), breech presentation, first pregnancy (primigravida), and high birth weight. Other factors include infants who are swaddled, infants born in the cold seasons of the year, female infants, and infants with torticollis.
Risk Factors • Laplanders and American Indians have an
increased incidence rate of DDH. The left hip is affected more commonly than is the right, and DDH is bilateral in 20% of cases. Family history is also an important factor in identification of those infants at risk for development of DDH. Conversely, infants at decreased risk for development of DDH include the black population and infants who are carried on the waist with the legs flexed and abducted.
Clinical Evaluation • Evaluation for hip dysplasia is part of every
newborn examination. The accuracy of the evaluation is affected by the experience of the physician; and infants in whom hip dysplasia does not develop until after birth may have normal examination results. Clinical findings associated with DDH include asymmetric skin folds of the thighs and one knee appearing lower than the other when the hips and knees are flexed. The subluxed or dislocated hip appears shorter (known as the Caleazzi or Allis' sign).
Clinical Evaluation • Clinical maneuvers can also be used to detect hip instability and dislocation, but performance of these maneuvers may be difficult if the infant is not relaxed. The two maneuvers are performed with the infant's hips and knees flexed, and one hip should be examined at a time. The Ortolani maneuver involves abduction of the thigh while the hip is gently pulled anteriorly If the hip is dislocated, the hip may relocate into the acetabulum with a palpable (and possibly audible) "clunk."
Ortolani maneuver
Clinical Evaluation • The Barlow maneuver is performed with adduction of the hip with a gentle posterior push in an effort to solicit subluxation or dislocation in an abnormal hip. These maneuvers are similar to those performed in a dynamic ultrasound evaluation.
SONOGRAPHIC EVALUATION OF INFANT HIPS • The technique for imaging the infant hip was
initially described by Craf who used a static approach. Harcke developed a dynamic approach to sonographic imaging. The two approaches were combined to develop a minimum standard examination. Imaging protocol should incorporate two orthogonal views with one view that includes stress views, which typically include the coronal/neutral or coronal/flexion view and the transverse flexion view.
SONOGRAPHIC EVALUATION OF INFANT HIPS • The transverse/neutral view and measurements
are considered optional, and anterior views have also been described. Particular attention should be taken to image each view in the correct plane and with the appropriate anatomy identified because a minimal shift in the image may lead to an inaccurate diagnosis. This chapter defines the images for the minimum standard examination and describes normal and abnormal findings.
Barlow maneuver.
• Infant hips may be examined sonographically
during the first year of life or until the ossification of the femoral head prevents adequate visualization. A linear transducer is preferred to avoid distortion and to cover a broader field of view. The highest frequency transducer should be used, and a 7.5-MHz transducer is recommended for infants from birth to 3 months of age, although 10-MHz transducers may be used in premature infants.
• A successful examination requires that the infant be relaxed for accurate stress maneuvers. Infants should be imaged in a warm environment with distracters such as toys, pacifiers, or bottles. A parent should be available and visible to the infant to assist in maintaining a relaxed environment. The infant should be placed in a supine, slightly oblique or lateral decubitus position to accommodate the lateral and posterolateral position of the transducer.
• Bolsters should be used as needed to stabilize the infant's
position. Harcke and Grissom5 suggest that the ultrasound professional scan the left hip with the right hand while maneuvering the hip with the left hand and scan the right hip with the left hand while performing stress maneuvers with the right hand. Because two hands are needed to adequately image and maneuver the hip, sonographic evaluation is often a joint effort between the sonographer and radiologist. The second person may assist in maneuvering the hip or producing the images, depending on institutional • protocol. A foot switch may also be used to acquire the images during stress maneuvers.
Coronal/Neutral View • The coronal/neutral view of the hip is obtained with
placement of the transducer in a coronal plane at the lateral aspect of the hip. The hip is maintained in a physiologic neutral position with approximately 15 to 20 degrees of flexion. The ultrasound image should demonstrate the midportion of the acetabulum, with the ilium appearing as a straight line parallel to the transducer.
Coronal/Neutral View • The junction of the ilium and triradiate cartilage
should be dearly identified, and the cartilaginous tip of the labrum should be visualized. The femoral metaphysis is also seen in this plane, which differentiates this view from the coronal/flexion view. A normal hip, A shows the hypoechoic femoral head resting against the acetabulum. An abnormal hip, B migrates laterally and superiorly.
Coronal/Neutral View • In this view, the alpha angle, C) may be obtained
with measurement of a line along the lateral aspect of the ilium with respect to the slope of the acetabulum. According to the Craf classification, a normal hip would have an alpha angle of 60 degrees or more (type I). A type II hip (50 to 60 degrees) would reflect a physiologic immaturity in infants less than 3 months of age and would require follow-up but no treatment.
Coronal/Neutral View • If a type II hip is identified in an infant of more than 3 months of age, then treatment would be necessary. A type III hip describes subluxation with a shallow acetabulum and an alpha angle of more than 50 degrees, and a type IV hip is a dislocated hip that lacks contact between the acetabulum and the femoral head. With the minimum standard examination, measurements are optional; however, they do provide a quantitative baseline for follow-up purposes.
Coronal/Neutral View • In this view, a more subjective assessment
method may be used with noting how deep the femoral head is located within the acetabulum. A normal hip shows at least 50% of femoral head coverage by the acetabulum. This can be assessed by drawing a line across the ilium through the femoral head and identifying whether 50% of the femoral head is below the line. On the basis of the amount of femoral head coverage, the hip tan be classified as sitting deep, intermediate, or shallow.
Coronal/Neutral View • A visual assessment of the acetabulum and any irregularities should also be described. The acetabulum becomes progressively deformed when hip dysplasia is present, and fibrofatty tissue develops (appearing as a soft tissue echoes) between the femoral head, thus preventing reduction of the hip.
A, Normal hip is shown in coronal/neutral view. Femoral head sits deep within bony acetabulum. B, In comparison, abnormal hip shows femoral head positioned laterally and superiorly. C, Normal hip shows alpha (a) and beta (b) angles used in Graf classification. H, Femoral head; ;, iliac line; L, lateral; m, femoral metaphysic; S, superior.
B
A
C
Coronal/Flexion View • The coronal/flexion view is also imaged from
the coronal plane, although the hip is flexed at a 90-degree angle. The sonographic appearance is similar to the coronal/ neutral view, with the exception of visualization of the bony metaphysis. The lateral margin of the ilium should appear as a straight line, and the femoral head should be identified resting within the acetabulum. As in the coronal/neutral view, the cartilaginous tip of the labrum is visualized.
Coronal/Flexion View • In this view, stress maneuvers can be performed
for assessment of instability of the hip. The stress maneuvers performed are similar to the Ortolani and Barlow maneuvers to test for the reduction of a dislocated hip or to identify whether or not the hip can be dislocated. The infant must be relaxed for accurate assessment of instability. Gentle guiding of the hip, moving of the hip from a neutral to flexed position, and abducting and adducting while administering a gentle push/pull are also important.
Coronal/Flexion View • The sonographer should observe and document the absence or presence of any instability' identified in real time. Notation of whether or not a dislocated hip will reduce is also important. The acetabulum should again be evaluated for any evidence of dysplasia.
Transverse/Flexion View • The transverse/flexion view is obtained with the infant's hip flexed at a 90-degree angle. The transducer is rotated
A, Normal coronal/flexion view is identified with femoral head resting against acetabulum. B, Dislocated hip shows soft tissue echoes in acetabulum that may prevent hip from being reduced without surgical intervention, a, Acetabulum; H, femoral head; I, iliac line; L, lateral; 5, superior; arrow, labrum.
A
B
• 90 degrees from a coronal to a transverse plane and
should be positioned slightly posterolaterally over the hip. The infant may need to be slightly oblique to accommodate the transducer position. The ultrasound image shows the femoral head and metaphysis, which is identified anterior to the femoral head; and the ischium is identified posterior to the femoral head. The normal hip appears to have a U-shaped configuration, A) as the metaphysis and ischium surround the femoral head. An abnormal hip, B) lacks this appearance as the femoral head shifts laterally with subluxation and posterolaterally with dislocation Stress maneuvers should be used as described in the coronal/flexion view to assess for instability and the ability to reduce a dislocated hip.
A, Normal transverse/flexion view shows U-shaped configuration that is not present in, B, dislocated hip. H, Femoral head; i, ischium; m. femoral metaphysic; L, lateral; P, posterior.
A
B
Pavlik harness is often used in treatment of hip dysplasia.
TREATMENT • Treatment of abnormal hips may vary depending
on the age at diagnosis and the severity of hip dysplasia. Some degree of laxity may be identified in the newbom period and resolve without intervention, although follow-up is necessary to ensure resolution of a subluxation. The triple diaper technique has also been used to prevent adduction without evidence of improvement when compared with infants without treatment within the first 3 weeks of life. Treatment for hip dysplasia is indicated for infants with subluxation beyond 3 weeks of life and for infants with hip dislocation.
TREATMENT • The Pavlik harness is the most common device used in
the treatment of hip dysplasia; it prevents adduction of the hips and is used for infants with hip subluxations and reducible dislocations. The typical treatment period is 3 months, during which time the infant may be monitored regularly with radiography or ultrasound and adjustments to the harness may be made as necessary. When treatment is followed with ultrasound, the Pavlik harness should initially be left in place. As the infant is weaned from the harness, the sonographer may be directed to perform the ultrasound examination without the harness. Infants who do not have successful treatment with the Pavlik harness and those infants with irreducible dislocations may require an abduction brace, casting, or operative reduction.
SUMMARY • Early diagnosis and treatment of hip dysplasia
can reduce infant morbidity. Risk factors or abnormal clinical examination results can be used to identify those infants who will achieve the greatest benefit from ultrasound screening. Sonography is an important. tool in the diagnosis, especially in those infants at risk with normal clinical examination results. A thorough knowledge of imaging technique is necessary to ensure reliability and reproducibility. This is of particular importance when ultrasound is used to follow the effectiveness of treatment.
CLINICAL SCENARIO— DIAGNOSIS • The femoral head is located in a shallow position within the acetabulum but is not completely dislocated. With proper patient compliance and follow-up for necessary adjustments, this infant may have successful treatment with a Pavlik harness.
CASE STUDIES FOR DISCUSSION • 1. A family practice resident examines a newborn in the first day of life. The hips feel unstable, and an ultrasound is ordered. The ultrasound reveals a Graf type II hip with an alpha angle of 54 degrees. What is the appropriate treatment for this infant?
CASE STUDIES FOR DISCUSSION • 2. An infant is seen with a positive Allis' sign on
the left side. Clinical examination is limited because of the fussy nature of the infant at the time of the appointment. An ultrasound is ordered to rule out hip dysplasia. The sonographer identifies a normal right hip and a dislocated left hip. As the sonographer performs stress maneuvers, the hip remains persistently out of the acetabulum. What are the treatment options for this infant?
• 3. A 5-week-old infant is referred for ultrasound to rule out hip dysplasia because of a positive family history. Ultrasound reveals the finding in. What is the diagnosis and treatment plan?
Coronal/neutral view identifies percentage of femoral head contained within acetabulum.
• 4. A sonographer presents the hip ultrasound image in to the radiologist. The radiologist asks the sonographer to repeat the view. Can you explain why?
• 5. A mother brings her 6-week-old child in for a 2-
week follow-up after placement of the Pavlik harness. Should the sonographer image the infant in or out of the harness?
Coronal/neutral view of hip.
