شكرا علي معلومات قيمة ولكن
هل توجد مكتبة طبية في منتدي؟ لو نعم كيف يتم وصول{مشترك جديد}في ليبيا ايضا
يتم اجراء فحص الزامي لورك الرضيع و هو في عمر شهر و نصف لتأكد من سلامته
Developmental dysplasia of the hip
INTRODUCTION — Developmental dysplasia of the hip (DDH) describes a spectrum of conditions in which the femoral head has an abnormal relationship to the acetabulum [1]. This condition also has been called congenital hip dis********, congenital dysplasia of the hip, congenital subluxation of the hip, and developmental dis******** of the hip. Developmental dysplasia of the hip is the preferred term . "Developmental" is preferred to "congenital" since the condition is not always present or identifiable at birth and may develop during the first few months of life . "Dysplasia" is preferred to "dis********" because it includes a broader spectrum of cases than the most severe dis********s.
TERMINOLOGY — DDH encompasses several abnormalities in the relationship between the femoral head and the acetabulum, all resulting in hip instability. These include : Dis******** — The femoral head is completely outside of the acetabulum; dis********s may be complete (eg, unreducible) or reducible by simple flexion and abduction depending upon the age of the child and the length of time that the hip has been dislocated. Two types of hip dis********s are described: teratologic and typical . Teratologic dis********s occur in utero, are associated with neuromuscular or syndromic conditions (eg, arthrogryposis, spina bifida, chromosomal abnormalities), and are not considered by most authors to be representative of DDH. Typical dis********s occur in otherwise healthy infants and may occur prenatally or postnatally. This discussion will focus on typical dis********s. Dislocatable — The femoral head is within the acetabulum, but can be completely displaced outside of the acetabulum by abduction and extension. Subluxable — The femoral head can be partially, but not completely, displaced outside of the acetabulum. Dysplasia — Dysplasia is usually not clinically apparent, but describes various radiographic abnormalities that reflect inadequate formation of the acetabulum.
EPIDEMIOLOGY — The incidence of hip instability is generally reported to be 1 per 100 births , whereas the incidence of true dis******** (ie, requiring intervention) is reported to be between 1 and 2 per 1000 infants . However, the incidence depends upon the diagnostic method (eg, physical examination versus ultrasonography) and the age of the child. In the evidence synthesis for the American Academy of Pediatrics (AAP) clinical practice guideline for the early detection of DDH, the incidence of DDH in newborns was estimated to be 8.6, 11.5, and 25 per 1000 examinations by pediatricians, orthopedists, and ultrasonography, respectively [15]. By six months of age, the incidence decreased to <0.34 per 1000 examinations for all diagnostic methods.
The incidence also varies by race: it is increased in the Lapp and Native American populations (to as high as 25 to 50 cases per 1000 births) , and decreased in populations of African descent.
Approximately 20 percent of cases are bilateral; among the unilateral cases, the left hip is affected three times more often than the right. The preponderance of left-sided cases may be related to left occiput anterior positioning in nonbreech infants (the most common fetal position), in which the left hip is forced into adduction against the mother's sacrum [].
Risk factors — The following conditions are associated with an increased risk of DDH: Female sex Breech presentation Family history of DDH Limited fetal mobility, particularly limited hip abduction Clinical evidence of persistent joint instability Significant persistent hip asymmetry Female sex — DDH is four to five times more common among female than male infants []. In the AAP evidence synthesis, described above, among studies using physical examination in newborns by an orthopedist, the incidence of DDH was estimated to be 19 per 1000 examinations in girls versus 4 per 1000 examinations in boys . The increased incidence in girls may be related to their increased susceptibility to the maternal hormone, relaxin, which may contribute to ligamentous laxity , or to breech positioning, which is more common in girls than boys . Breech presentation — Breech presentation increases the risk of DDH. In the AAP evidence synthesis [], the odds ratio for DDH given a breech presentation was 7.0. Breech presentation is thought to increase the risk for DDH via mechanical factors (forced adduction with extension of the knees, show figure 1). The risk is greater among infants with frank breech versus footling breech presentations . Family history of DDH — Genetic factors appear to play a role in the development of D[]. In one review of 589 patients with DDH, the risk of recurrence in subsequent children was reported to be 6 percent when there was one affected child, 12 percent when there was one affected parent, and 36 percent when there was an affected parent and an affected child . Concordance among monozygotic twins is 34 percent, whereas it is only 3 percent among dizogotic twins. In the AAP evidence synthesis , the odds ratio for DDH among patients with a family history was 1.7 (which was not statistically significant). Limited fetal mobility — Any condition in which fetal mobility, particularly abduction of the hips, is limited, may increase the risk of DDH. Examples include breech position (discussed above), oligohydramnios , firstborn infants (in which the unstretched abdominal muscles and primagravida uterus may subject the fetus to prolonged abnormal positioning that limits mobility) ].
Increased birth weight (>4000 g) is described as a risk factor in some , but not all [], studies. Similarly, multiple gestations are an inconsistent risk factor . The association of the above conditions with DDH supports the theory that the "crowding phenomenon" plays a role in the pathogenesis of DDH.
In addition, infants who are born with congenital postural or foot deformities (eg, tortic35-], plagiocephaly, ****tarsus adductus , clubfoot), also have an increased rate of DDH, although the association with clubfoot is inconsistent . In these cases, all of the abnormalities may be related to abnormal intrauterine position leading to crowding and limited fetal mobility []. Limited postnatal mobility — Limited mobility in the postnatal period also may play a role in the development of DDH. Extrauterine risk factors for DDH include swaddling cloths and cradle boards . These practices force the newborn leg out of its physiologic position (knee flexion contractures and hip flexion, abduction, and external rotation contractures) and into adduction and extension.
PATHOGENESIS — DDH has a multifactorial pathogenesis. Ligamentous laxity, which probably has a genetic component, predisposes the developing hip to mechanical forces that cause the femoral head to move outside of the acetabulum . Dysplasia appears to be the result, rather than cause, of dis********.
Normal hip development — A basic understanding of the growth and development of the hip is necessary to understand the pathogenesis of DDH. The femoral head and acetabulum develop from the same primitive mesenchymal cells, into which a cleft forms by the 7th week of gestation . By the 11th week of gestation the hip joint is fully formed, although acetabular development continues throughout intrauterine life.
Initially, the hip joint is deeply set and spherical . However, in utero, the femoral head grows at a faster rate than the acetabulum, so that by the end of gestation the femoral head is less than 50 percent covered, the shallowest point in its development. During the final four weeks of gestation, the hip is particularly vulnerable to mechanical forces that direct the femoral head away from the central portion of the acetabulum (eg, adduction. Within a few weeks of birth, the growth rate of the acetabular cartilage surpasses that of the femoral head, resulting in progressively increased coverage [].
At birth, the femoral head and acetabulum are cartilaginous. Postnatal development of the acetabulum involves growth of the labrum and deepening of the socket. The acetabular cartilage has a triradiate orientation: in the horizontal, vertical, and anterior directions. There is a fibrocartilaginous labrum at the margin of the acetabular rim with the joint capsule inserting just above the rim . Interstitial growth within the triradiate cartilage leads to increased diameter of the hip joint. Before ossification of the acetabulum (at approximately three months of age), deformation of the acetabulum is entirely reversible [].
During the first months of infancy, the proximal femur is entirely cartilaginous [48,49]. The proximal ossification center of the femur appears at 4 to 7 months of age and has three main growth areas : The proximal physeal plate, which contributes 30 percent of the growth of the femur The greater trochanter, where appositional growth is stimulated by traction of the abductors The cartilaginous isthmus of the femoral neck, which connects the femoral neck and trochanteric growth plates and contributes to the lateral ***** of the femoral neck; this cartilaginous isthmus remains active until maturity.
Pathologic hip development — DDH is not merely capsular laxity, but a pathologic entity, characterized by defective posterior bony coverage of the femoral head by the acetabuluة. The pathologic changes of DDH occur along a spectrum in time and severity. Changes begin with laxity of the hip joint capsule, which permits the femoral head to move out of the acetabulum. This movement results in eversion of the labrum, elongation of the ligamentum teres, and prevents normal ossification of the acetabulum . Older children with DDH often develop secondary centers of ossification in the pubic epiphysis, iliac epiphysis, and ischial epiphysis.
With progression, the femoral head dislocates and the labrum inverts and develops a hypertrophied ridge (the neolimbus) . Intraarticular structures including the ligamentum teres and fibrofatty tissue (pulvinar) may begin to hypertrophy and prevent re******** of the femoral head into the acetabulum]. With continued dis********, contractures can develop in the iliopsoas and hip adductors, further preventing abduction of the leg and efforts to reduce the hip. A false acetabulum may form where the femoral head contacts the lateral wall of the pelvis above the normal ********.
The abnormal growth forces cause deformation of the cartilaginous proximal femur and acetabulum with several possible consequences, including : Flattening of the femoral head Valgus neck-shaft angle Excessive femoral anteversion Acetabular dysplasia
Natural history — Abnormalities that are present at birth are actively modulated by ongoing growth of the femur and acetabular cartilage ]. Most unstable hips in newborns stabilize soon after birth []. In observational studies, high rates of resolution without intervention have been reported ]. Using his examination technique (see "Hip instability" below), Barlow noted that 60 percent of the hips that demonstrated instability at birth stabilized in the first week of life, and nearly 90 percent stabilized by two months of age [33]. These hips were functionally and radiographically normal at 12 months of age. Similar results have been reported with routine ultrasonographic screening of more than 14,000 infants: 6 percent had abnormal neonatal scans, 90 percent of which became normal by 9 weeks of age [57].
Some children who have stable hips in the newborn period have abnormal radiographs at four months of age [7], highlighting the rationale for the change in terminology to "developmental" rather than "congenital" hip dysplasia, and the need for persistent monitoring.
The natural history of untreated DDH depends upon its severity, bilaterality, and the extent of development of a false acetabulum [50,60]. Untreated unilateral or bilateral dis******** may lead to varying degrees of functional disability, pain, and accelerated degenerative hip disease [60-62]. Patients with unilateral dis********s may have leg length discrepancy, ipsilateral knee deformity and pain, scoliosis, and gait disturbance [50]. Those with bilateral dis******** may develop back pain (perhaps related to lordosis). Hip pain is increased in patients with a well-developed false acetabulum.
Patients with subluxation or dysplasia may be diagnosed incidentally when radiographs are obtained for other reasons. The clinical course is variable. In some patients, radiographic abnormalities improve with time [46,63]; others may develop hip pain and degenerative joint disease. The pain is activity-related. It typically develops soon after skeletal maturity [60], and in females, during the first or second pregnancy, and at menopause [50].
CLINICAL FEATURES — The clinical features of DDH depend upon the age of the child and the severity of abnormality (show table 1) [4]. The spectrum of presentation ranges from instability on the newborn examination, limited abduction in the infant, limping in the toddler, painful dysplasia in the adolescent, and osteoarthritis in the adult [64]. The earlier DDH is detected, the simpler and more effective the treatment [14,65].
History — Important aspects of the history include ascertainment of risk factors for DDH, including [3,66]: Pre- and perinatal history: oligohydramnios; breech presentation (even if it was transient); multiple gestation; birth weight Other musculoskeletal abnormalities (eg, torticollis, ****tarsus adductus, equinovarus, in-toeing) Family history of DDH Ethnic background (increased risk in Laplanders, Native Americans) Postnatal risk factors: swaddling with hips in extension and adduction
Examination — Assessment for DDH should occur at every well child visit until the child is walking normally (usually by two years of age). It is important to explain the hip examination to the parents as it is being performed, and to ******** the results at each visit.
Because of the developmental nature of DDH, the specifics of the examination vary depending upon the age of the child. In the first three to four months of life, it is important to evaluate the stability of the hips and symmetry of femur length and posterior thigh folds (recognizing that some infants have bilateral DDH). Once the infant is approximately four months old, tests for instability have less utility because of the increased muscle size and bulk and, in undetected cases of DDH, the development of hip contractures [1,4]. After four months of age, limited abduction and leg length discrepancy (Galeazzi, AIIis, or Perkins sign) are better indicators of DDH. In older children with unilateral DDH, the Trendelenburg test (inability to maintain the pelvis horizontally while standing on the ipsilateral leg) may be positive because of weakness of the hip abductors on the affected side.
**Hip instability — Physical examination techniques to detect hip instability were originally described by Ortolani [54], Coleman [67], and Barlow [33]: Ortolani described the pathology of the click sign, which occurs as the femoral head is dislocated from the acetabulum, or reduced into the acetabulum [54]. The click sign indicates a defect in the superior aspect of the acetabulum. Coleman described the "jerk of exit," the palpable sensation of displacement of the femoral head when posterior lateral force is applied [67]. He acknowledged that it is difficult to discern whether the direction of instability is out-in or in-out. Barlow described similar findings of unstable hips: the femoral head slipping forward into the acetabulum or out over the posterior lip of the acetabulum [33].
Although the de******ion of the positive finding varies, Ortolani, Coleman, and Barlow each describe an identical test for hip instability in the newborn. This maneuver represents the basis for instability testing, and is performed as follows (show figure 5):
Each hip should be examined individually for instability. The examination should occur when the infant is calm and not crying [12]. The infant should be examined in the supine position, with the hip flexed to 90º, and the leg in neutral rotation. The examiner's index and middle fingers are placed along the greater trochanter and his or her thumb along the inner thigh; the leg should be grasped loosely. The hip is gently adducted while directing the knee posteriorly. A palpable clunk or sensation of movement will be detected as the femoral head exits the acetabulum if the hip is dislocatable (the "jerk of exit" described by Coleman [67]). A sliding movement or a feeling of looseness characterizes a subluxable hip [10]. The hip is then gently abducted while lifting the leg anteriorly. If the hip is dislocatable, this maneuver reduces it and is accompanied by a palpable clunk.
The combination of these maneuvers has a high specificity (98 to 99 percent) in the detection of hip instability [68-71]. The sensitivity varies depending upon the skill of the examiner and the number of examinations performed [72-74]. In experienced hands, sensitivity is between 87 and 99 percent [69-71].
**Asymmetry — Asymmetry of the inguinal (show figure 6), thigh (show figure 7), or gluteal folds, observed with the infant in the prone position, may be an important clue to the diagnosis of DDH. This finding is sensitive, but not specific for DDH, since asymmetry is present in approximately 24 percent of all infants [75].
Apparent shortening of the femur is another important sign in unilateral dis********. This finding is elicited with the Galeazzi test (also called the Allis or Perkins test). The test is performed with the infant supine, hips flexed to 90º, knees flexed, and feet flat on a level surface. In this position, the knees are normally at the same level. In unilateral dis********, the head of the femur is displaced posteriorly, and the ipsilateral knee will be lower than the other knee (show figure 8). In infants with typical dis********s, apparent shortening of the femur is not usually present at birth; other causes of congenital femur length discrepancy should be considered (eg, hemihypertrophy) [12].
In the child who is walking, gait asymmetry may provide a clue to unilateral DDH. The abnormal gait is usually caused by leg length discrepancy, resulting in toe-walking on the affected side. However, it may be as subtle as asymmetric in-toeing or out-toeing [4]. The thigh of the affected side tends to be held in partial lateral rotation, fixation, and flexion [26].
**Range of motion — When the infant is supine and the pelvis stabilized, the hips should be able to be abducted to >75º and adducted to 30º past the midline [3,4,10,67]. In a child older than three months, limitation of abduction (<45º is the most reliable sign of DDH [4,10]. In one review of 683 infants older than three months, unilateral limited hip abduction was present in 69 percent of infants with abnormal ultrasonography and absent in 54 percent of those with normal ultrasonography [76].
**Bilateral DDH — Bilateral DDH is particularly difficult to identify because asymmetry is lacking [4]. The instability test is useful in younger infants. After the development of soft tissue contractures, important findings include widening of the perineum, symmetric limited abduction, and abnormally short thigh segments relative to the child's size. Once the child begins to walk, hyperlordosis and a waddling gait are classic findings.
RADIOGRAPHIC EVALUATION
Plain radiographs — Plain radiographs have limited value during the first few (<4) months of life before the femoral heads are ossified. The bony landmarks are indistinct, making displacement and instability difficult to detect. At this age, plain radiographs are only helpful if they are abnormal. However, radiographs may be indicated in young infants with neuromuscular disorders, myelodysplasia, or arthrogryposis to assess other bony abnormalities (eg, congenital coxa vera, proximal femoral focal deficiency, congenital short femur, and sacral agenesis) [66].
If a radiograph is requested in a newborn, it should consist of a single anterior-posterior (AP) view with the hips held in 20º to 30º flexion. The flexion is necessary to accommodate the physiologic flexion contracture of the newborn hip. The AP view is preferred because positioning the infant for the frog-leg lateral view may reduce a dis******** if one is present, providing false reassurance that the hip is normal.
After four months of age, plain radiographs become more reliable in the evaluation of DDH [10]. When radiographs are obtained, the hips should be in neutral position [66]. The von Rosen view (legs at 45º angle, abducted, and thighs internally rotated) may accentuate a dislocated hip that is not apparent on the AP view. A frog-leg lateral view should be obtained to assess reduction when the neutral view is abnormal.
As with the examination, the classic radiographic findings of DDH vary by age, and include [9]: Widened pelvic floor Decreased femoral head coverage (show radiograph 1) Delayed appearance of the femoral ossific nucleus on the involved side or dissimilar sizes of the ossific nuclei Increased acetabular index (>40º in newborn or infant) (show figure 9) [67]; this measurement is problematic because of interobserver and intraobserver variability [77,78] Failure of the medial ****physeal beak of the proximal femur and secondary ossification center to be located in the inner quadrant, as defined by Hilgenreiner's and Perkins' lines (also called the Y line and Ombredanne's lines, respectively) (show figure 10) Medial gap (distance between the most medial portion of proximal femur and a line drawn perpendicular to the lateral edge of the acetabulum) exceeds 5 mm [66] Disruption of the Shenton line after 3 to 4 years of age (show figure 11) [79,80] Absent teardrop figure (U figure or teardrop of Koehler) (show figure 12) (because of lack of or inadequate stimulation from the capital epiphysis) [81]
Ultrasonography — During the first few months of life, ultrasonography can be used to visualize the morphology and stability of the hip, and is an important adjunct to the clinical evaluation [10,82]. It can be helpful in confirming physical examination findings, evaluating high-risk infants, and making treatment decisions [82]. In young infants, ultrasonography is ideally suited to guide reduction of the dislocated hip; to evaluate the reduction and stability of the hip during therapy; to monitor the hip in traction; and to evaluate closed reductions [83]. The major drawback of ultrasonography is that accurate interpretation requires training and experience [84].
Both static and dynamic ultrasonography of the hip have been described. Static ultrasonography involves a single coronal image with the infant in the lateral decubitus position and the hips flexed at 30 to 45º [85,86]. In this position, the ossified ilium is a straight white line and the roof of the acetabulum is the ossified medial wall of the acetabulum and the labrum (show figure 13 and show radiograph 2). The alpha angle is the angle formed by the ossified lateral wall of the ilium and the bony roof line. The beta angle is the angle formed by the ossified lateral wall of the ilium and the cartilaginous roof line [79,85]. According to the Graf classification, the hips are classified into one of four types, depending upon measurement of the alpha and beta angles, appearance of the superior bony rim, and amount of femoral coverage (show table 2).
The coronal ultrasonographic image, when rotated, is similar to the AP hip radiograph. Similar views of the ilium are present in both modalities; the ischium seen on the radiograph is similar to the medial acetabulum seen with ultrasonography. The femoral ****physis can be seen on the radiograph, whereas the femoral head can be identified with ultrasonography. The abductor muscles and the lateral wall of the ilium are the first landmarks to identify. The percentage of subluxation of the femoral head is measured from this lateral wall line.
The dynamic technique describes axial and coronal images with real time stress of the femoral head similar to the instability test maneuvers [87]. In the first few days of life, 4 to 6 mm of laxity is considered normal.
The American College of Radiology Appropriateness Criteria [66] and the American Institute of Ultrasound in Medicine Guidelines [88] combine static and dynamic techniques to include a coronal view in the standard plane and a transverse view with the hip flexed with and without a modified Barlow stress maneuver. This combination permits evaluation of hip morphology, position, and stability. Application of stress is omitted when the hips are examined during treatment [88].
Computed tomography — Computed tomography (CT) may be useful preoperative planning and post-reduction monitoring. It is valuable for surgical planning by evaluating femoral anteversion. Postreduction CT has predictive value for development of avascular necrosis (AVN), by measuring the abduction angle of the hip. CT provides precise information regarding the position of the femoral head within the acetabulum in the cast and confirms successful reduction. Pediatric protocols that involve reduced dose of radiation are available.
Conventional arthrography — Conventional arthrography is used as a guide intraoperatively to confirm the position of the femoral head and to visualize structures that may block the reduction of the hip.
Magnetic resonance imaging — Magnetic resonance imaging (MRI) is most useful in the preoperative assessment of complicated DDH and in the evaluation of postsurgical reduction and long-term sequelae of partially treated or untreated DDH. Contrast-enhanced MRI shows the position and shape of the cartilaginous femoral head and obstacles to reduction without the radiation of CT, as well as changes of the acetabulum not demonstrated by ultrasonography (US) or plain radiography. MRI also gives information about the vascularity of the cartilaginous femoral head and can detect ischemia. Global decrease in perfusion of the femoral head is associated with significantly increased likelihood of AVN [89]. If ossification of the femoral head does not occur by one year of age, avascular necrosis (AVN) is believed to be present [90].
DIAGNOSIS — The diagnosis of DDH in infants is usually made by physical examination demonstrating hip instability. If the results are questionable, confirmation may be obtained through physical examination by a more experienced examiner (eg, pediatric orthopedic surgeon or senior pediatrician) or radiologic studies (ultrasonography in infants younger than 4 months and plain radiography thereafter) [9].
INDICATIONS FOR ORTHOPEDIC REFERRAL — Referral to an orthopedic surgeon who is familiar with the diagnosis and treatment of DDH is indicated when unstable hips are detected, whether during the newborn examination, two-week examination, or any time thereafter [10]. Because it is not possible to predict the outcome of unstable hips in newborns (eg, spontaneous resolution, dis********, dysplasia), all newborns with clinical instability should be treated [9]. (See "Management" below). The AAP recommends against ordering ultrasonographic or radiographic studies in these infants before they are seen by the consultant, who may use a variety of imaging studies during management and follow-up.
In addition, referral to an orthopedic surgeon who is familiar with the diagnosis and treatment of DDH is indicated for infants who have *****ocal examination findings after two weeks of age (eg, soft "click" rather than clunk during instability testing). Alternatively, the pediatric health care provider may obtain imaging studies (ultrasonography in those <5 months, radiographs in those >4 months) to evaluate DDH [9]. The infant's risk factors should be factored into this decision, with the lowest threshold of referral for girls who are born breech, followed by boys who are born breech and girls with a positive family history, and higher thresholds for girls who were not born breech and boys with a positive family history.
MANAGEMENT — The goals of treatment of DDH are to obtain and maintain concentric reduction of the hip to provide an optimal environment for the development of the femoral head and acetabulum. The cartilage of the surface of the femoral head must be in contact with the cartilage of the floor of the acetabulum [4]. The acetabulum has the capacity for development many years after reduction if concentric reduction is maintained [91,92].
The goals of treatment are the same whether the infant is diagnosed in the newborn nursery or later in infancy [4,9]. However, the therapies necessary to achieve that goal depend upon the age of diagnosis and the degree of abnormality.
0 to 6 months
**Pavlik harness — Infants younger than six months who have dislocatable or subluxable hips are usually treated with abduction splints (eg, Pavlik harness, Aberdeen splint, von Rosen splint). The Pavlik harness is most commonly used [65]. The Pavlik harness is a dynamic splint that prevents hip extension and adduction (which can lead to dis********), but permits flexion and abduction (stabilizing and reducing unstable and dislocated hips, respectively) (show figure 14) [4]. Contraindications to the use of the Pavlik harness are listed in the table (show table 3).
The harness is worn until clinical, radiographic, and ultrasonographic evaluations are normal [65]. The duration of treatment varies depending upon age of the infant and severity of DDH, but a minimum of three months is usually necessary [65]. Children who are older than 4 months at the time of diagnosis usually must wear the harness for a duration equal to twice their age. Treatment with the Pavlik harness should be discontinued after three weeks of age in infants whose hips are not clearly reduced by clinical and ultrasonographic examination [65]. Such infants should be treated with a fixed adduction brace if reduction is questionable, or more definitive therapy (eg, traction, adductor tenotomy, reduction) if the hip is not reduced [65].
Frequent (eg, weekly) adjustments are necessary to maintain the ideal position during the first several weeks of therapy because of the rapid growth rate of infants at this age [4]. Ultrasonography can be used to monitor position and evidence of subluxation or dis******** [65]. In infants with complete dis********, imaging should be obtained to ******** adequate flexion and redirection of the femoral neck [9]. Infants who are treated with the Pavlik harness should be monitored for femoral nerve compression and brachial plexus palsy.
Treatment with the Pavlik harness is effective if used before six months of age. Hip instability resolves in 95 percent of cases [9,65,93]. The success rate for complete dis******** is approximately 85 percent [65,94-96], with success defined as achievement and maintenance of hip reduction.
Early failure of the Pavlik harness treatment for DDH has been predicted when there is low percentage coverage (<20 percent) of the femoral head and irreducible dis******** on physical examination [97].
Although treatment with the Pavlik harness is usually safe, potential complications include delayed acetabular development, inferior dis********s (from prolonged excessive hip flexion) [98], femoral nerve compression, brachial plexus palsy, knee subluxation, and skin breakdown [9,65]. The most serious (and rare) complication is osteonecrosis (avascular necrosis) of the femoral head from forced abduction or persistent use of the harness despite failure of guided reduction in infants with complete dis******** [9]. This complication may also occur in the opposite hip [99,100]. The reported incidence of osteonecrosis varies widely and may be affected by the age at reduction, the use of prereduction traction, or the severity of DDH [93,96,101].
**Triple diapering — Although it has been recommended in the past, triple diapering is not effective. It promotes hip extension, which is an unfavorable position for normal hip development [4].
>6 months — Open or closed reduction is usually necessary for children who are older than six months of age at the time of diagnosis or initiation of therapy [4,9]. The success rate for the Pavlik harness in children in this age group is less than 50 percent [9]. Open reduction is usually necessary for children who are older than two years of age [9].
Long-term follow-up — The frequency and duration of long-term follow-up depends to some extent, upon the treating orthopedic surgeon. As a general rule, children treated for hip dysplasia should have annual radiographs until they are at least six years old to look for late presenting complications such as avascular necrosis and to ensure that the hip is developing normally.
OUTCOME — The long-term outcome of treated DDH, depends upon the severity. The long-term outcome of untreated DDH is discussed above. (See "Natural history" above).
In one prospective study of 332 infants (546 hips) treated with a Pavlik harness for DDH (detected via a selective screening program), infants were monitored with ultrasonography during therapy and with annual radiographs; 90 percent were followed for a mean of 6.5 years [96]. Treatment was successful in 97 percent of hips with DDH and 85 percent of dislocated hips. Among the successfully reduced hips, 2.4 percent showed persistent significant late dysplasia (center edge angle [CEA] <20º, and 1 percent required surgery. Many of these patients could be identified by progression of the acetabular index by 18 months of age, and all were identified by CEA angle <20º by five years of age. Avascular necrosis was noted in 1 percent of hips. This study suggests that radiologic surveillance should be continued until at least five years of age.
In another report, 61 patients with 74 dislocated hips (reducible or irreducible) were followed for a mean of 12 years. All hips appeared radiographically normal at three and five years of follow-up. However, at latest follow-up, 17 percent of the hips demonstrated acetabular changes, emphasizing the importance of follow-up until patients reach skeletal maturity.
SCREENING — It is important to detect DDH as early as possible since early detection enables less invasive and more effective therapy.
However, the method of screening and population to be screened are controversial.
The ideal screening test should detect as many infants as possible who, without intervention, would go on to have clinically significant disease; it must also avoid overdiagnosis, which leads to unnecessary treatment and possible complications of therapy [102]. Much of the information necessary to perform this calculation is unknown (eg, the
extent to which abduction splinting alters long-term outcome, whether those at risk for isolated acetabular dysplasia in adulthood can be identified in infancy, and whether early treatment can prevent the development or persistence of dysplasia) [102-104].
Factors that must be considered in evaluating screening methods for DDH include: the lack of a uniform definition of clinically significant disease (eg, that which will require splinting, or that which will require surgery or that which is likely to cause long-term complications), the natural history of spontaneous resolution, and the low prevalence (so that even with a sensitive and specific test, the majority of positive screens will be falsely positive) [103,105]. In addition, the net balance of risks and benefits of intervention is unclear because of the lack of experimental or prospective cohort studies comparing functional outcomes of intervention versus no intervention [103-105]. (See "Glossary of common biostatistical and epidemiological terms", section on Predictive values).
Selective screening of "high-risk" infants to increase the prevalence in the screened population is one strategy to decrease the number of false positive examinations and improve the positive-predictive value [23,106]. However, because not all infants with DDH have identifiable risk factors [26,107,108], selective screening cannot be expected to detect all cases of DDH. In addition, a universal definition of "high risk" has not been established [109]. Most studies include breech infants and those with a family history of DDH; inclusion of other risk factors has been variable. (See "Risk factors" above).
The tests that are used for early detection of DDH (the instability test and ultrasonography) require training and experience for accurate execution and interpretation. The results of screening programs that have been reported to be effective in one area may not be generalizable to areas. Even with universal screening programs (both clinical and ultrasonographic), DDH continues to be detected in children older than 12 months [110].
Clinical — The physical examination should be used to screen for DDH at every health supervision visit, beginning with newborn examination and continuing until the child is walking and is walking normally (usually by about 2 years of age) [10].
Once serial clinical screening became routine practice, the operative rate for DDH decreased from 1 to 2 per 1000 infants [70,111] to 0.2 to 0.7 per 1000 infants [10,72,112]. However, a review of DDH surgery after establishment of universal clinical screening programs in the United Kingdom reported that only 30 percent of children who underwent surgery for DDH had been detected through universal screening; 35 percent were detected primarily as a result of parental concern [113].
The major disadvantage to clinical screening is that the sensitivity to detect DDH depends upon the experience and training of the examiner [10,15]. In addition, examination by the most experienced examiners cannot detect all cases of DDH [5,8,110].
Ultrasonographic — Universal screening with ultrasonography is performed in some countries [114,115] and has been advocated by some as a means of improving the sensitivity of detection of DDH [57,114,116]. Others, however, are firmly against this approach because of the as-yet-unproven favorable risk-benefit ratio [105,117,118].
Ultrasonography during the first four weeks of life often reveals minor degrees of instability or acetabular immaturity, many of which resolve spontaneously [57,103,115,117]. Thus, universal newborn screening of infants with ultrasonography has the potential to lead to overdiagnosis of DDH, requiring a high frequency of reexamination, and an increased number of treated hips (with the attendant risks of treatment).
In some centers, universal ultrasonographic screening has led to little, if any, reduction in late-diagnosed cases, but to increased numbers of infants requiring treatment (more than 30 per 1000 [114,119,120], compared to between 4 and 11 per 1000 with selective screening [23,106,121]). However, this is not the case in all centers, particularly the most experienced where, with serial screening, only 2.4 per 1000 infants are treated [57]. Other centers report a reduction in late-diagnosed cases and surgical procedures, albeit with an increased treatment rate (49 per 1000), and a long "learning curve" [116].
Selective screening of "high-risk" infants is one strategy to decrease the number of false positive examinations with ultrasonographic screening [23,106,122]. However, risk factors alone have a poor predictive value if used to decide who needs testing. In one selective screening program, among infants referred on the basis of physical examination, 1 dis******** was detected for every 11 infants screened [108]. In contrast, among infants referred for risk factors alone, 1 dis******** was detected for every 75 infants screened [108]. Selective ultrasonographic screening of infants who have abnormal examinations is a strategy that has become common practice in many areas [102], but does not appear to reduce the overall rate of surgery, compared to the best clinical screening programs [123,124].
Ultrasonographic screening strategies were compared in a trial in which 11,925 infants were randomly assigned to universal, selective, or no ultrasonographic screening; all infants were clinically screened [119]. The following findings were noted: Ultrasonographic screening resulted in increased treatment rates (3.4, 2.0, and 1.8 in the universal, selective, and no ultrasonography groups, respectively). Among untreated infants, screening resulted in a higher follow-up rate (13, 1.8, 0 percent, in the universal, selective, and no ultrasonography groups, respectively). There was a nonsignificant trend toward lower prevalence of late DDH among the ultrasonographically screened infants (0.3, 0.7, and 1.3 per 1000 in the universal, selective, and no screening groups, selectively).
In a systematic review, the Canadian Task Force on Preventive Health Care estimated that 1003 and 1962 infants would have to be universally screened with ultrasound to prevent one case of subluxation or dis******** requiring treatment and operative intervention, respectively; and that 1693 and 3550 infants would have to be selectively screened to prevent one case of subluxation or dis*****
19-Oct-2007, 07:09 PM 
خلع الورك الولادي 
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