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Musculoskeletal Screening: Developmental Dysplasia of the Hip Amanda C. Roof, MD; Thomas M. Jinguji, MD; and Klane K. White, MD
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Abstract
1. Discover the proper techniques for identifying and diagnosing developmental dysplasia of the hip (DDH) on physical exam. 2. Identify proper imaging modalities to use as an adjunct to the physical exam. 3. Clearly delineate when a referral to a DDH specialist is necessary. Amanda C. Roof, MD, is an orthopedic surgery resident, University of Washington School of Medicine. Thomas M. Jinguji, MD, is Clinical Associate Professor, Department of Orthopedics and Sports Medicine, Seattle Children’s Hospital. Klane K. White, MD, is Associate Professor, Department of Orthopedics and Sports Medicine, Seattle Children’s Hospital. Address correspondence to: Thomas M. Jinguji, MD, 4800 Sand Point Way, O9.A.120, Seattle, WA 98105; email: thomas.jinguji@ seattlechildrens.org. Disclosure: The authors have no relevant financial relationships to disclose. doi: 10.3928/00904481-20131022-10
© Shutterstock
Developmental dysplasia of the hip (DDH) is common because it is present in 1 of 100 newborns. Failure to diagnose DDH and treat in infancy can result in significant long-term disability. Early diagnosis can be accomplished through a quick but careful physical examination of all newborns. Further selective screening by ultrasound is indicated for those children with risk factors for DDH, which include family history, breech presentation, and unstable hip examination at the initial newborn examination. Continued examination of the hip at all routine well-child checkups is mandatory through the first year of life because late presenting DDH may occur. Treatment with a Pavlik harness is not typically instituted in the neonate because many unstable hips stabilize without intervention, but it is indicated in children older than 2 weeks with hip instability. Ultrasound screening for infants with risk factors for DDH is recommended at age 6 weeks. Pavlik harness treatment for children with unstable hips or significant dysplasia on ultrasound is continued until the hips stabilize and show concentric reduction on imaging. With time, diagnosis and treatment evolve to accommodate the growing child. Infants who fail to respond to nonoperative management may require more extensive interventions. At any time when treatment is initiated, a DDH specialist should be involved in the patient’s care. If DDH is recognized early, treatment is less invasive, and long-term effects are minimized.
educational objectives
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he term developmental dysplasia of the hip (DDH) is composed of a spectrum of pathologies from stable acetabular dysplasia (femoral head centered in acetabulum but acetabulum is shallow) to concentric hips that are unstable (femoral head can be moved in and out of the confines of the acetabulum) and frankly dislocated hips in which there is a complete loss of contact between the femoral head and acetabulum. Congruent reduction and stability of the femoral head are necessary for normal growth and development of the hip joint. The natural history of DDH is variable; acetabular dysplasia often resolves spontaneously, and unstable or dislocated hips may reduce without treatment. Some will require treatment to normalize. Whether dysplastic, unstable, or completely dislocated, DDH in the newborn period is pain-free and asymptomatic. This makes its diagnosis difficult for all providers. Failure to recognize this entity can have drastic results. In cases that have persistent dysplasia or untreated dislocation, infants have a significantly increased risk of developing precocious arthritis and mild to debilitating hip pain as young adults.1,2 Therefore, the early detection and treatment of DDH are important in avoiding the poor outcome associated with a late diagnosis. Fortunately, the diagnosis of DDH requires only modest vigilance for detection in most cases. To make this review most useful for the general pediatrician, we frame the remainder of our discussion to answer questions that are often directed toward DDH specialists in our pediatric orthopedic surgery and sports medicine department. INCIDENCE AND ETIoLOGY Patient Profiles DDH occurs in 11.5 of 1,000 infants, with frank dislocations occurring in 1 to 1.5 of 1,000.3,4 Although all children
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Table 1.
Risk Factors for DDH Risk Factor
Absolute Risk per 1,000 Newborns
Family history (first-degree relative) - Female
44
- Male
9.4
Figure 1. The Galeazzi sign. In this figure, the left femur appears shorter than the right. This is one indication that the left hip may be dislocated. (From the Merck Manual of Diagnosis and Therapy.12 ©2010-2013 by Merck Sharp & Dohme Corp., a subsidiary of Merck & Co, Inc, Whitehouse Station, NJ; with permission.)
Breech presentation - Female
120
- Male
26
Unstable hip at newborn examination
—
DDH = developmental dysplasia of the hip. Adapted from American Academy of Pediatrics3
should be screened for DDH by physical examination, particular risk factors exist for DDH that warrant closer scrutiny. These risk factors include positive family history, breech presentation, and the presence of an unstable hip examination at birth (Table 1). The left hip alone is affected in 60% of infants, the right hip in 20% of infants, and both hips in 20% of infants. An explanation behind the left-hip predominance may be attributed to the typical left occiput anterior presentation during vaginal birth. This position causes the left hip to be adducted because it abuts the mother’s lumbosacral spine. Girls’ hips are more sensitive to the ligamentous laxity induced by the maternal hormone relaxin, which is thought to contribute to the higher incidence of DDH in female infants.3,4 Although these risk factors demonstrate patterns, the true etiology of DDH remains a debate in the literature. A recent study from the United Kingdom shows preliminary data suggesting that in singleton breech infants, “the mode of delivery is the critical factor promoting dislocation, not the breech presentation itself” because the rate of DDH was significantly lower in those delivered by cesarean section versus vaginal delivery.5 This adds to traditional hypotheses of intrauterine mechanical factors plus hor-
monal factors being the greatest influence on developing DDH.6 In contrast, however, infants of multiple gestations are not at an increased risk for DDH, although both monozygotic and dyzygotic twins are reported to have more “positional anomalies” thought to be caused by increased intrauterine constraint.7,8 Perhaps similar to preterm neonates, babies born from multiple gestations are protected by their typical preterm birth and low birth weight. Even with these sometimes contradicting ideas, the debate is closed on which patients to screen in the newborn nursery; regardless of risk factors, every newborn should be examined for DDH. Despite newborn screening programs, 1 in 5,000 children will have a dislocated hip detected after age 18 months.9 It is important to appreciate that even with underlying dysplasia, associated dislocated hips are not always present at birth, and not all hips dislocated at birth are detectable in the newborn period. Subtypes of DDH Dislocations can be divided into two groups: syndromic and typical. Syndromic (also referred to as teratologic) dislocations are those that occur early in gestation and frequently present with other syndromes or disorders, such as
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neuromuscular conditions like myelodysplasia and arthrogryposis or with dysmorphic syndromes such as Larsen syndrome.3 These abnormalities develop between weeks 12 to 18 of gestation. Syndromic dislocations are often fixed and nonreducible and require orthopedic referral for the discussion of operative management.10 Typical dislocations develop in otherwise healthy infants during the third trimester or postnatal period. The remainder of this article addresses only typical dislocations. Physical Findings There are no pathognomonic signs of a dislocated hip, and a stable dysplastic hip has no physical findings. The physical examination requires patience on the part of the examiner with a quiet and calm infant. This may be facilitated by having the baby feed from a bottle and dimming the room light. An evaluation for asymmetry of hip movement is an important key to the evaluation of DDH, although asymmetry may not be evident in bilateral dislocations. The presence of asymmetric thigh folds may be indicative of DDH but is present in up to 20% of unaffected infants. Asymmetric thigh folds in the absence of other physical examination findings should be considered a nonspecific finding and do not require further imaging or workup. However, the presence of asymmetric flexed hip abduction is suggestive of a dislocation. The most common examination maneuvers are described later. Each sign, in-
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Figure 2. (A) The Ortolani sign. With the hip flexed to 90 degrees and the leg gently abducted. If the hip is dislocated initially, the reduction of the hip with abduction will produce a palpable clunk. (B) The Barlow sign: the hips are flexed to 90 degrees and adducted. Then, a gentle downward force is placed on the leg. A clunk can be appreciated if the hip is unstable and dislocates posteriorly. (From Guille et al.7 ©2000 American Academy of Orthopaedic Surgeons. Reprinted from the Journal of the American Academy of Orthopaedic Surgeons, Volume 8(4), pp. 232-242 with permission.)
dividually or in combination, may serve to increase the index of suspicion of the examiner and lower the threshold for further diagnostic studies or referral to an experienced DDH specialist.
90 degrees. With the baby’s hips in neutral abduction, the examiner determines if the knees are at the same height. If one femur appears shorter, the hip may be dislocated posteriorly.
Limited Hip Abduction Hip abduction is performed with the hip in flexion, and side-to-side variations should be noted. An arc from 30 degrees of adduction to 75 degrees of abduction should be easily obtained when the infant is in the supine position.3 Limited hip abduction (difference of 20 degrees or greater between hips) is the most reliable examination finding suggestive for DDH in babies older than 12 weeks when Ortolani and Barlow tests (further described below) become difficult to perform.11
Ortolani Test Originally described in 1937,13 the Ortolani maneuver (see Figure 2a) is performed to assess the stability of the hip, one leg at a time, with the calm newborn supine on the examining table. In the classic description, the pelvis is stabilized by placing the thumb and ring/long finger of one hand on top of both anterior iliac crests simultaneously while performing the maneuver with the opposite hand. In common practice and recommended by the authors, the pelvis is stabilized by holding the opposite thigh in the same manner as the examined side. First, the index and middle fingers of the examiner are placed along the greater trochanters of each leg while the thumb is placed on the medial aspect of the leg. Care should be taken to exam-
Galeazzi Sign The Galeazzi sign (see Figure 1)12 is elicited with the patient placed supine on an examining table so that the pelvis is level, with the hips and knees flexed to
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ine one side at a time while stabilizing the pelvis by holding the opposite side in neutral abduction. While holding the opposite hip flexed to 90 degrees, the hip is examined in neutral external/internal rotation and then gently abducted while applying an upward force on the right greater trochanter. A palpable “clunk” is felt as the dislocated femoral head reduces into the acetabulum. This finding is reported as Ortolani positive. Ortolani negative means this clunk is not felt, and, thus, the hip is dislocated and irreducible (ie, a fixed dislocation). In common parlance, Ortolani negative is often used improperly to describe a stable hip by many providers. To prevent this confusion, there should be clear communication between providers. Barlow Test Originally described by Barlow in 1952,14 this test is an attempt to dislocate or subluxate a reduced but unstable hip (see Figure 2b). The thigh is held and the pelvis stabilized in the same manner as for the Ortolani test. With the hip in neutral external/internal rotation and at 90 degrees of flexion, the leg is gently adducted with a mild posteriorly directed pressure applied to the knee. A palpable “clunk” or sensation of a marked posterior movement constitutes a positive result, meaning the patient has a reduced hip at rest that can be dislocated. Each hip should be examined separately. High-pitched “clicks” are frequently elicited with the hip range of motion. These sounds are most frequently attributed to snapping of the iliotibial band over the greater trochanter, a normal occurrence, and are not associated with dysplasia.15 To differentiate between a “clunk” of the Ortolani and Barlow tests and a tendon “click” takes time and experience. With progressive soft-tissue contractures and the increasing size of the patient after age 3 months, both the Ortolani and Barlow tests become unreliable, leaving limited flexed hip 232 | Healio.com/Pediatrics
A
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B
C
Figure 3. (A) An example of a normal hip ultrasound in which the femoral head is well seated in the acetabulum (thin white line = femoral head; dotted line = acetabular cartilage; thick line = labrum). (B) An abnormal ultrasound of a dislocated hip in which the femoral head is laterally and superiorly displaced and the labrum is blunted. (C) A schematic of a normal hip ultrasound. Normal values are an alpha angle of greater than 60 degrees and percent coverage of more than 50% (in a child >12 weeks).
abduction and the Galeazzi sign as the best indicators of DDH. Even in these larger and older infants, a gentle force should be sufficient to elicit a clunk if an unstable hip is present; firm pressure is never necessary. In children of walking age, true “late presenting” hip dislocation is pain-free. These children will start to walk at a normal age. Often, only a minor limp or gait difference is noted by the family. Physical examination findings for hip dislocation in the walking child include persistent loss of flexed hip abduction, Galeazzi sign, apparent leg length discrepancy, and a Trendelenburg gait. Other physical examination findings, such as torticollis and metatarsus adductus, can be associated with DDH. The initial evaluation of an infant with an isolated finding of torticollis or metatarsus adductus should include a careful, focused evaluation of the hips. If the hip examination is stable and no risk factors for DDH are noted, no further imaging or evaluation is necessary beyond standard repeat hip examinations at wellchild checkups through 12 months.3 Imaging: type, frequency and patient identification Imaging of the immature hip is a valuable adjunct to the physical examination. An anteroposterior (AP) X-ray of the pelvis is difficult to interpret before age 4 to 5 months because the femoral
head is composed entirely of cartilage until the secondary center of ossification appears. Before the appearance of the secondary center, ultrasound examination is the method of choice for visualizing the cartilaginous femoral head and acetabulum (see Figure 3). Static ultrasound images allow visualization of acetabular and femoral head anatomy, whereas the complementary dynamic images give information on the stability of the hip joint.16-18 The accuracy of hip ultrasonography is limited by the experience and skill of the operator, especially when performed within the first 3 weeks of life.18 Even if the ultrasound is executed perfectly, clinicians must be aware that ultrasound images in newborns often reveal minor degrees of dysplasia that usually resolve spontaneously and may lead to overtreatment of physiological hip variations. Marks et al19 in 1994 documented that approximately 77% of the ultrasounds with mild dysplasia at birth normalized when repeated at 4 weeks and 90% in 9 weeks. Thus, ultrasonography is the technique of choice for screening infants with risk factors for DDH up to age 4 months (ideally between age 6 to 12 weeks) and is useful in following the results of intervention. However, ultrasonography is not recommended as a screening tool for infants without risk factors.3,20 The authors primarily use femoral head coverage16 and alpha angle18 when evaluating neonatal
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Images courtesy of Amanda C. Roof, MD.
CM E ultrasounds. Normal femoral head coverage should exceed 50%, and the alpha angle should exceed 60 degrees (see Figure 3). In the preterm child, routine ultrasound screening of the stable hip with risk factors (or the unstable hip that stabilizes spontaneously) should be performed at chronologic age rather than corrected age. Breech presentation in the premature infant does not cause the same level of intrauterine constraint and restriction as is the case in term infants. Studies indicate that prematurity reduces the associated risk of DDH in breech presentation; a study by Bick et al21 found that the alpha angle in preterm infants was higher than in children born at term. Thus, for standardization and ease, it is not necessary to correct for gestational age in deciding on the timing of ultrasound of the hip. After age 4 months, the femoral head is ossified, and, thus, the gold standard imaging modality transitions to the AP pelvic radiograph. The reference lines and angles used on X-ray imaging are displayed in Figure 4. Note that hip radiography should be performed at an adjusted age to allow normal ossification assessments and better visualization of the femoral head. course of Treatment All newborns should be screened for DDH by a properly trained healthcare provider by physical examination (see Figure 5). If premature, subsequent examinations and treatment of the infant should follow recommendations as determined by chronologic age not adjusted age. Radiographs are the exception and should be interpreted at an adjusted age because premature bone requires the same amount of developmental time to ossify. In either case, when a newborn’s hip examination is suggestive of hip dysplasia, the patient should be sent to an experienced DDH specialist for a confirmatory examination or the examination
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Figure 4. Radiographic analysis of developmental dysplasia of the hip. (From Guille et al.7 ©2000 American Academy of Orthopaedic Surgeons. Reprinted from the Journal of the American Academy of Orthopaedic Surgeons, Volume 8(4), pp. 232-242 with permission.)
should be repeated in 2 weeks based on clinician preference. If the hip remains unstable beyond age 2 to 5 weeks, the newborn should be referred to a provider experienced with the management of DDH. However, if the instability resolves by 2 to 5 weeks, then age-appropriate imaging (ultrasonography at 6 weeks or X-ray after 4 months) is warranted in addition to future well-child checkups. Clear communication between providers is encouraged if the practitioner examining the newborn in the hospital is different from the 2-week follow-up examiner.3 If there are no risk factors, then serial examinations are recommended at well-child visits until the child is an established walker (~12 months). If during these periodic visits physical findings raise suspicion of hip dysplasia or if there is a parental concern of hip disease, a referral to a medical provider with expertise in medical and surgical management of newborn hip disease is strongly recommended. This provider can confirm physical examination findings, ensure that age-appropriate imaging is being performed, and begin treatment if necessary.
If the examination shows a stable hip but the baby has positive risk factors, then age-appropriate imaging is recommended. This can be ultrasonography at 6 weeks or an X-ray at 4 months. Of note is that the 2000 DDH clinical practice guideline recommends imaging of stable hips only for females born breech and not for other risk factors.3 Our recommendation to screen all infants with risk factors differs from the guidelines. This is an effort to make decisions regarding imaging simpler, more straightforward, and more uniform. For stable hips with acetabular dysplasia in children older than 6 weeks, the authors recommend treatment for patients in which the ultrasound shows an alpha angle less than 50 degrees and femoral head coverage less than 40%. If the ultrasound shows an alpha angle greater than 50 degrees and femoral head coverage above 40%, ultrasound should be repeated in 4 to 6 weeks because this mild dysplasia may represent normal physiologic variation and resolve spontaneously.19 Referral to a DDH specialist should be made if the follow-up ultrasound remains abnormal. For children 0 to 6 months, DDH Healio.com/Pediatrics | 233
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Image courtesy of Wheaton Brace Company.
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Figure 5. The recommended algorithm for neonatal screening of developmental dysplasia of the hip (DDH). Indications for ultrasonographic screening include instability on physical examination, a family history of DDH, and breech presentation. All ages are chronologic, not adjusted. AP = anteroposterior; FHC = femoral head coverage; PE = physical examination. (Adapted from Terjesen et al16 and Graf18)
Table 2.
Pavlik Treatment Success Severity of Dysplasia Based on PE
Success (%)
Stable
~100
Unstable - Barlow positive
>90
- Ortolani positive
64–93
Irreducible (Ortolani negative)
40
PE = physical examination. Adapted from Sucato et al;20 Viere et al;22 Hangen et al;23 Lerman et al;24 and Swaroop and Mubarak25
is treated with a Pavlik harness, and if older or larger, an abduction orthosis is used because the child can overpower the Pavlik harness. Again, the treatment of preterm infants should be based on chronologic age not adjusted age. The Pavlik harness is a dynamic splint that allows the infant to actively move its hips through a sphere of motion that encourages deepening and stabilization of the acetabulum (see Figure 6). The har234 | Healio.com/Pediatrics
ness is applied as soon as possible after the diagnosis of DDH requiring treatment is made and initially worn at all times. It is crucial to have staff available with time to teach as well as to provide take-home information for parents. This should allow the family to initially feel comfortable caring for the infant while in the brace and eventually feel confident in removing and reapplying the brace properly to allow bathing.
Figure 6. Proper fitting of the Pavlik harness is shown in a frontal view. The hips should be held in 90 degrees of flexion and neutral abduction/ adduction, with the straps then tightened. The infant should then sit in a relaxed position of flexion and abduction. Hyperflexion and hyperabduction are associated with femoral nerve palsy and femoral head osteonecrosis, respectively.
The length of treatment is dependent on the age at presentation and improvement of standard measurements on imaging. Progress is judged by serial physical examinations, static and/or dynamic ultrasonography, or serial AP pelvis Xray in patients older than 4 months. In the case of a frankly dislocated hip, Pavlik harness treatment is generally abandoned if no improvement is noted within 4 weeks of harness application. The success of Pavlik harness treatment is variable and correlates with the severity of the hip dysplasia. Treatment success is summarized in Table 2.20,22-25 Unfortunately, the use of a Pavlik harness is not without risks; excessive abduction of the patient’s hips can lead to avascular necrosis of the femoral head (in 0%–22%), and excessive flexion may result in femoral nerve palsy. Thus, proper position is critical with the hips abducted greater than 60 degrees when they are flexed to 90 degrees but with posterior straps lax enough to al-
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low the knees to be passively adducted to the midline26 (see Figure 6). A provider or orthotist experienced in Pavlik placement and instruction of the parents are crucial for the success of treatment while still ensuring safety. At our institution, we have patients return in a week to confirm adequate harness placement. If the hip is extremely unstable, we often recommend that parents keep the Pavlik on 24 hours per day until returning to the clinic in 1 week. It must be stressed that triple diapering is never an accepted form of treatment in DDH at any age. When a fixed dislocation is present or no improvement is made with Pavlik harness management after 4 weeks, closed reduction under general anesthesia with arthrographic evaluation and subsequent spica casting are attempted at 4 to 5 months (adjusted age for premature infants). For hips not amenable to closed reduction, open operative reduction of the hip with spica casting and often an adductor tendon tenotomy are required. Early, successful management reduces the risk for future operations such as pelvic osteotomies or early total hip replacement.2 Summary The diagnosis of DDH represents a spectrum of disorders that is common (ie, noted in about 1 of 100 newborns). In the newborn period, DDH is an asymptomatic condition and can be overlooked. All providers taking care of newborn children should know how to recognize DDH and when to refer these children for appropriate treatment. All newborns should be screened for DDH by physical examination. Early recognition of DDH is critical. Performing a careful physical examination, being aware of DDH risk factors, and obtaining appropriate and timely imaging are needed for this diag-
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nosis. Once the diagnosis is made, treatment for DDH is usually straightforward and generally successful. REFERENCES 1. Cooperman DR, Wallensten R, Stulberg SD. Acetabular dysplasia in the adult. Clin Orthop Relat Res. 1983;(175):79-85. 2. Wedge JH, Wasylenko MJ. The natural history of congenital disease of the hip. J Bone Joint Surg Br. 1979;61(3):334-338. 3. American Academy of Pediatrics. Clinical practice guideline: early detection of developmental dysplasia of the hip. Committee on Quality Improvement, Subcommittee on Developmental Dysplasia of the Hip. Pediatrics. 2000;105(4 Pt 1):896-905. 4. Guille JT, Pizzutillo PD, MacEwen GD. Development dysplasia of the hip from birth to six months. J Am Acad Orthop Surg. 2000;8(4):232-242. 5. Panagiotopoulou N, Bitar K, Hart WJ. The association between mode of delivery and developmental dysplasia of the hip in breech infants: a systematic review of 9 cohort studies. Acta Orthop Belg. 2012;78(6):697-702. 6. Hinderaker T, Daltveit AK, Irgens LM, Udén A, Reikerås O. The impact of intra-uterine factors on neonatal hip instability. An analysis of 1,059,479 children in Norway. Acta Orthop Scand. 1994;65(3):239-242. 7. Sionek A, Czubak J, Kornacka M, Grabowski B. Evaluation of risk factors in developmental dysplasia of the hip in children from multiple pregnancies: results of hip ultrasonography using Graf’s method. Ortop Traumatol Rehabil. 2008;10(2):115-130. 8. Bielski RJ, Gesell MW, Teng AL, Cooper DH, Muraskas JK. Orthopaedic implications of multiple gestation pregnancy with triplets. J Pediatr Orthop. 2006;26(1):129-131. 9. Dezateux C, Godward S. Evaluating the national screening programme for congenital dislocation of the hip. J Med Screen. 1995;2(4):200-206. 10. LeBel M-E, Gallien R. The surgical treatment of teratologic dislocation of the hip. J Pediatr Orthop B. 2005;14(5):331-336. 11. Jari S, Paton RW, Srinivasan MS. Unilateral limitation of abduction of the hip. A valuable clinical sign for DDH? J Bone Joint Surg Br. 2002;84(1):104-107. 12. Merck Manual of Diagnosis and Therapy. Porter R (ed). Hip, leg, and foot abnormalities Available at http://www.merckmanuals. com/professional/pediatrics/congenital_craniofacial_and_musculoskeletal_abnormalities/hip_leg_and_foot_abnormalities.
html?qt=galeazzi%20sign&alt=sh. Accessed Oct. 21, 2013. 13. Ortolani M. Un segno poco noto e sua importanza per la diagnosi precoce di prelussazione congenita dell’anca. Paediatria (Napoli). 1937;45:129. 14. Barlow TG. Early diagnosis and treatment of congenital dislocation of the hip. J Bone Joint Surg Br. 1962;44(2):292-301. 15. Bond CD, Hennrikus WL, DellaMaggiore ED. Prospective evaluation of newborn softtissue hip “clicks” with ultrasound. J Pediatr Orthop. 1997;17(2):199-201. 16. Terjesen T, Bredland T, Berg V. Ultrasound for hip assessment in the newborn. J Bone Joint Surg Br. 1989;71(5):767-773. 17. Clarke NM, Harcke HT, McHugh P, et al. Real-time ultrasound in the diagnosis of congenital dislocation and dysplasia of the hip. J Bone Joint Surg Br. 1985;67(3):406-412. 18. Graf R. Fundamentals of sonographic diagnosis of infant hip dysplasia. J Pediatr Orthop. 1984;4(6):735-740. 19. Marks DS, Clegg J, al-Chalabi AN. Routine ultrasound screening for neonatal hip instability. Can it abolish late-presenting congenital dislocation of the hip? J Bone Joint Surg Br. 1994;76(4):534-538. 20. Sucato DJ, Johnston CE 2nd, Birch JG, Herring JA, Mack P. Outcome of ultrasonographic hip abnormalities in clinically stable hips. J Pediatr Orthop. 1999;19(6):754–759. 21. Bick U, Müller-Leisse C, Tröger J. Ultrasonography of the hip in preterm neonates. Pediatr Radiol. 1990;20(5):331-333. 22. Viere RG, Birch JG, Herring JA, Roach JW, Johnston CE. Use of the Pavlik harness in congenital dislocation of the hip. An analysis of failures of treatment. J Bone Joint Surg Am. 1990;72(2):238-244. 23. Hangen DH, Kasser JR, Emans JB, Millis MB. The Pavlik harness and developmental dysplasia of the hip: has ultrasound changed treatment patterns? J Pediatr Orthop. 1995;15(6):729-735. 24. Lerman JA, Emans JB, Millis MB, et al. Early failure of Pavlik harness treatment for developmental hip dysplasia: clinical and ultrasound predictors. J Pediatr Orthop. 2001;21(3):348-353. 25. Swaroop VT, Mubarak SJ. Difficult-to-treat Ortolani-positive hip: improved success with new treatment protocol. J Pediatr Orthop. 2009;29(3):224-230. 26. Kitoh H, Kawasumi M, Ishiguro N. Predictive factors for unsuccessful treatment of developmental dysplasia of the hip by the Pavlik harness. J Pediatr Orthop. 2009;29(6):552-557.
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Musculoskeletal Screening: Developmental Dysplasia of the Hip Amanda C. Roof, MD; Thomas M. Jinguji, MD; and Klane K. White, MD
CM E
Abstract
1. Discover the proper techniques for identifying and diagnosing developmental dysplasia of the hip (DDH) on physical exam. 2. Identify proper imaging modalities to use as an adjunct to the physical exam. 3. Clearly delineate when a referral to a DDH specialist is necessary. Amanda C. Roof, MD, is an orthopedic surgery resident, University of Washington School of Medicine. Thomas M. Jinguji, MD, is Clinical Associate Professor, Department of Orthopedics and Sports Medicine, Seattle Children’s Hospital. Klane K. White, MD, is Associate Professor, Department of Orthopedics and Sports Medicine, Seattle Children’s Hospital. Address correspondence to: Thomas M. Jinguji, MD, 4800 Sand Point Way, O9.A.120, Seattle, WA 98105; email: thomas.jinguji@ seattlechildrens.org. Disclosure: The authors have no relevant financial relationships to disclose. doi: 10.3928/00904481-20131022-10
© Shutterstock
Developmental dysplasia of the hip (DDH) is common because it is present in 1 of 100 newborns. Failure to diagnose DDH and treat in infancy can result in significant long-term disability. Early diagnosis can be accomplished through a quick but careful physical examination of all newborns. Further selective screening by ultrasound is indicated for those children with risk factors for DDH, which include family history, breech presentation, and unstable hip examination at the initial newborn examination. Continued examination of the hip at all routine well-child checkups is mandatory through the first year of life because late presenting DDH may occur. Treatment with a Pavlik harness is not typically instituted in the neonate because many unstable hips stabilize without intervention, but it is indicated in children older than 2 weeks with hip instability. Ultrasound screening for infants with risk factors for DDH is recommended at age 6 weeks. Pavlik harness treatment for children with unstable hips or significant dysplasia on ultrasound is continued until the hips stabilize and show concentric reduction on imaging. With time, diagnosis and treatment evolve to accommodate the growing child. Infants who fail to respond to nonoperative management may require more extensive interventions. At any time when treatment is initiated, a DDH specialist should be involved in the patient’s care. If DDH is recognized early, treatment is less invasive, and long-term effects are minimized.
educational objectives
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T
he term developmental dysplasia of the hip (DDH) is composed of a spectrum of pathologies from stable acetabular dysplasia (femoral head centered in acetabulum but acetabulum is shallow) to concentric hips that are unstable (femoral head can be moved in and out of the confines of the acetabulum) and frankly dislocated hips in which there is a complete loss of contact between the femoral head and acetabulum. Congruent reduction and stability of the femoral head are necessary for normal growth and development of the hip joint. The natural history of DDH is variable; acetabular dysplasia often resolves spontaneously, and unstable or dislocated hips may reduce without treatment. Some will require treatment to normalize. Whether dysplastic, unstable, or completely dislocated, DDH in the newborn period is pain-free and asymptomatic. This makes its diagnosis difficult for all providers. Failure to recognize this entity can have drastic results. In cases that have persistent dysplasia or untreated dislocation, infants have a significantly increased risk of developing precocious arthritis and mild to debilitating hip pain as young adults.1,2 Therefore, the early detection and treatment of DDH are important in avoiding the poor outcome associated with a late diagnosis. Fortunately, the diagnosis of DDH requires only modest vigilance for detection in most cases. To make this review most useful for the general pediatrician, we frame the remainder of our discussion to answer questions that are often directed toward DDH specialists in our pediatric orthopedic surgery and sports medicine department. INCIDENCE AND ETIoLOGY Patient Profiles DDH occurs in 11.5 of 1,000 infants, with frank dislocations occurring in 1 to 1.5 of 1,000.3,4 Although all children
230 | Healio.com/Pediatrics
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Table 1.
Risk Factors for DDH Risk Factor
Absolute Risk per 1,000 Newborns
Family history (first-degree relative) - Female
44
- Male
9.4
Figure 1. The Galeazzi sign. In this figure, the left femur appears shorter than the right. This is one indication that the left hip may be dislocated. (From the Merck Manual of Diagnosis and Therapy.12 ©2010-2013 by Merck Sharp & Dohme Corp., a subsidiary of Merck & Co, Inc, Whitehouse Station, NJ; with permission.)
Breech presentation - Female
120
- Male
26
Unstable hip at newborn examination
—
DDH = developmental dysplasia of the hip. Adapted from American Academy of Pediatrics3
should be screened for DDH by physical examination, particular risk factors exist for DDH that warrant closer scrutiny. These risk factors include positive family history, breech presentation, and the presence of an unstable hip examination at birth (Table 1). The left hip alone is affected in 60% of infants, the right hip in 20% of infants, and both hips in 20% of infants. An explanation behind the left-hip predominance may be attributed to the typical left occiput anterior presentation during vaginal birth. This position causes the left hip to be adducted because it abuts the mother’s lumbosacral spine. Girls’ hips are more sensitive to the ligamentous laxity induced by the maternal hormone relaxin, which is thought to contribute to the higher incidence of DDH in female infants.3,4 Although these risk factors demonstrate patterns, the true etiology of DDH remains a debate in the literature. A recent study from the United Kingdom shows preliminary data suggesting that in singleton breech infants, “the mode of delivery is the critical factor promoting dislocation, not the breech presentation itself” because the rate of DDH was significantly lower in those delivered by cesarean section versus vaginal delivery.5 This adds to traditional hypotheses of intrauterine mechanical factors plus hor-
monal factors being the greatest influence on developing DDH.6 In contrast, however, infants of multiple gestations are not at an increased risk for DDH, although both monozygotic and dyzygotic twins are reported to have more “positional anomalies” thought to be caused by increased intrauterine constraint.7,8 Perhaps similar to preterm neonates, babies born from multiple gestations are protected by their typical preterm birth and low birth weight. Even with these sometimes contradicting ideas, the debate is closed on which patients to screen in the newborn nursery; regardless of risk factors, every newborn should be examined for DDH. Despite newborn screening programs, 1 in 5,000 children will have a dislocated hip detected after age 18 months.9 It is important to appreciate that even with underlying dysplasia, associated dislocated hips are not always present at birth, and not all hips dislocated at birth are detectable in the newborn period. Subtypes of DDH Dislocations can be divided into two groups: syndromic and typical. Syndromic (also referred to as teratologic) dislocations are those that occur early in gestation and frequently present with other syndromes or disorders, such as
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neuromuscular conditions like myelodysplasia and arthrogryposis or with dysmorphic syndromes such as Larsen syndrome.3 These abnormalities develop between weeks 12 to 18 of gestation. Syndromic dislocations are often fixed and nonreducible and require orthopedic referral for the discussion of operative management.10 Typical dislocations develop in otherwise healthy infants during the third trimester or postnatal period. The remainder of this article addresses only typical dislocations. Physical Findings There are no pathognomonic signs of a dislocated hip, and a stable dysplastic hip has no physical findings. The physical examination requires patience on the part of the examiner with a quiet and calm infant. This may be facilitated by having the baby feed from a bottle and dimming the room light. An evaluation for asymmetry of hip movement is an important key to the evaluation of DDH, although asymmetry may not be evident in bilateral dislocations. The presence of asymmetric thigh folds may be indicative of DDH but is present in up to 20% of unaffected infants. Asymmetric thigh folds in the absence of other physical examination findings should be considered a nonspecific finding and do not require further imaging or workup. However, the presence of asymmetric flexed hip abduction is suggestive of a dislocation. The most common examination maneuvers are described later. Each sign, in-
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Figure 2. (A) The Ortolani sign. With the hip flexed to 90 degrees and the leg gently abducted. If the hip is dislocated initially, the reduction of the hip with abduction will produce a palpable clunk. (B) The Barlow sign: the hips are flexed to 90 degrees and adducted. Then, a gentle downward force is placed on the leg. A clunk can be appreciated if the hip is unstable and dislocates posteriorly. (From Guille et al.7 ©2000 American Academy of Orthopaedic Surgeons. Reprinted from the Journal of the American Academy of Orthopaedic Surgeons, Volume 8(4), pp. 232-242 with permission.)
dividually or in combination, may serve to increase the index of suspicion of the examiner and lower the threshold for further diagnostic studies or referral to an experienced DDH specialist.
90 degrees. With the baby’s hips in neutral abduction, the examiner determines if the knees are at the same height. If one femur appears shorter, the hip may be dislocated posteriorly.
Limited Hip Abduction Hip abduction is performed with the hip in flexion, and side-to-side variations should be noted. An arc from 30 degrees of adduction to 75 degrees of abduction should be easily obtained when the infant is in the supine position.3 Limited hip abduction (difference of 20 degrees or greater between hips) is the most reliable examination finding suggestive for DDH in babies older than 12 weeks when Ortolani and Barlow tests (further described below) become difficult to perform.11
Ortolani Test Originally described in 1937,13 the Ortolani maneuver (see Figure 2a) is performed to assess the stability of the hip, one leg at a time, with the calm newborn supine on the examining table. In the classic description, the pelvis is stabilized by placing the thumb and ring/long finger of one hand on top of both anterior iliac crests simultaneously while performing the maneuver with the opposite hand. In common practice and recommended by the authors, the pelvis is stabilized by holding the opposite thigh in the same manner as the examined side. First, the index and middle fingers of the examiner are placed along the greater trochanters of each leg while the thumb is placed on the medial aspect of the leg. Care should be taken to exam-
Galeazzi Sign The Galeazzi sign (see Figure 1)12 is elicited with the patient placed supine on an examining table so that the pelvis is level, with the hips and knees flexed to
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ine one side at a time while stabilizing the pelvis by holding the opposite side in neutral abduction. While holding the opposite hip flexed to 90 degrees, the hip is examined in neutral external/internal rotation and then gently abducted while applying an upward force on the right greater trochanter. A palpable “clunk” is felt as the dislocated femoral head reduces into the acetabulum. This finding is reported as Ortolani positive. Ortolani negative means this clunk is not felt, and, thus, the hip is dislocated and irreducible (ie, a fixed dislocation). In common parlance, Ortolani negative is often used improperly to describe a stable hip by many providers. To prevent this confusion, there should be clear communication between providers. Barlow Test Originally described by Barlow in 1952,14 this test is an attempt to dislocate or subluxate a reduced but unstable hip (see Figure 2b). The thigh is held and the pelvis stabilized in the same manner as for the Ortolani test. With the hip in neutral external/internal rotation and at 90 degrees of flexion, the leg is gently adducted with a mild posteriorly directed pressure applied to the knee. A palpable “clunk” or sensation of a marked posterior movement constitutes a positive result, meaning the patient has a reduced hip at rest that can be dislocated. Each hip should be examined separately. High-pitched “clicks” are frequently elicited with the hip range of motion. These sounds are most frequently attributed to snapping of the iliotibial band over the greater trochanter, a normal occurrence, and are not associated with dysplasia.15 To differentiate between a “clunk” of the Ortolani and Barlow tests and a tendon “click” takes time and experience. With progressive soft-tissue contractures and the increasing size of the patient after age 3 months, both the Ortolani and Barlow tests become unreliable, leaving limited flexed hip 232 | Healio.com/Pediatrics
A
CM E
B
C
Figure 3. (A) An example of a normal hip ultrasound in which the femoral head is well seated in the acetabulum (thin white line = femoral head; dotted line = acetabular cartilage; thick line = labrum). (B) An abnormal ultrasound of a dislocated hip in which the femoral head is laterally and superiorly displaced and the labrum is blunted. (C) A schematic of a normal hip ultrasound. Normal values are an alpha angle of greater than 60 degrees and percent coverage of more than 50% (in a child >12 weeks).
abduction and the Galeazzi sign as the best indicators of DDH. Even in these larger and older infants, a gentle force should be sufficient to elicit a clunk if an unstable hip is present; firm pressure is never necessary. In children of walking age, true “late presenting” hip dislocation is pain-free. These children will start to walk at a normal age. Often, only a minor limp or gait difference is noted by the family. Physical examination findings for hip dislocation in the walking child include persistent loss of flexed hip abduction, Galeazzi sign, apparent leg length discrepancy, and a Trendelenburg gait. Other physical examination findings, such as torticollis and metatarsus adductus, can be associated with DDH. The initial evaluation of an infant with an isolated finding of torticollis or metatarsus adductus should include a careful, focused evaluation of the hips. If the hip examination is stable and no risk factors for DDH are noted, no further imaging or evaluation is necessary beyond standard repeat hip examinations at wellchild checkups through 12 months.3 Imaging: type, frequency and patient identification Imaging of the immature hip is a valuable adjunct to the physical examination. An anteroposterior (AP) X-ray of the pelvis is difficult to interpret before age 4 to 5 months because the femoral
head is composed entirely of cartilage until the secondary center of ossification appears. Before the appearance of the secondary center, ultrasound examination is the method of choice for visualizing the cartilaginous femoral head and acetabulum (see Figure 3). Static ultrasound images allow visualization of acetabular and femoral head anatomy, whereas the complementary dynamic images give information on the stability of the hip joint.16-18 The accuracy of hip ultrasonography is limited by the experience and skill of the operator, especially when performed within the first 3 weeks of life.18 Even if the ultrasound is executed perfectly, clinicians must be aware that ultrasound images in newborns often reveal minor degrees of dysplasia that usually resolve spontaneously and may lead to overtreatment of physiological hip variations. Marks et al19 in 1994 documented that approximately 77% of the ultrasounds with mild dysplasia at birth normalized when repeated at 4 weeks and 90% in 9 weeks. Thus, ultrasonography is the technique of choice for screening infants with risk factors for DDH up to age 4 months (ideally between age 6 to 12 weeks) and is useful in following the results of intervention. However, ultrasonography is not recommended as a screening tool for infants without risk factors.3,20 The authors primarily use femoral head coverage16 and alpha angle18 when evaluating neonatal
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Images courtesy of Amanda C. Roof, MD.
CM E ultrasounds. Normal femoral head coverage should exceed 50%, and the alpha angle should exceed 60 degrees (see Figure 3). In the preterm child, routine ultrasound screening of the stable hip with risk factors (or the unstable hip that stabilizes spontaneously) should be performed at chronologic age rather than corrected age. Breech presentation in the premature infant does not cause the same level of intrauterine constraint and restriction as is the case in term infants. Studies indicate that prematurity reduces the associated risk of DDH in breech presentation; a study by Bick et al21 found that the alpha angle in preterm infants was higher than in children born at term. Thus, for standardization and ease, it is not necessary to correct for gestational age in deciding on the timing of ultrasound of the hip. After age 4 months, the femoral head is ossified, and, thus, the gold standard imaging modality transitions to the AP pelvic radiograph. The reference lines and angles used on X-ray imaging are displayed in Figure 4. Note that hip radiography should be performed at an adjusted age to allow normal ossification assessments and better visualization of the femoral head. course of Treatment All newborns should be screened for DDH by a properly trained healthcare provider by physical examination (see Figure 5). If premature, subsequent examinations and treatment of the infant should follow recommendations as determined by chronologic age not adjusted age. Radiographs are the exception and should be interpreted at an adjusted age because premature bone requires the same amount of developmental time to ossify. In either case, when a newborn’s hip examination is suggestive of hip dysplasia, the patient should be sent to an experienced DDH specialist for a confirmatory examination or the examination
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Figure 4. Radiographic analysis of developmental dysplasia of the hip. (From Guille et al.7 ©2000 American Academy of Orthopaedic Surgeons. Reprinted from the Journal of the American Academy of Orthopaedic Surgeons, Volume 8(4), pp. 232-242 with permission.)
should be repeated in 2 weeks based on clinician preference. If the hip remains unstable beyond age 2 to 5 weeks, the newborn should be referred to a provider experienced with the management of DDH. However, if the instability resolves by 2 to 5 weeks, then age-appropriate imaging (ultrasonography at 6 weeks or X-ray after 4 months) is warranted in addition to future well-child checkups. Clear communication between providers is encouraged if the practitioner examining the newborn in the hospital is different from the 2-week follow-up examiner.3 If there are no risk factors, then serial examinations are recommended at well-child visits until the child is an established walker (~12 months). If during these periodic visits physical findings raise suspicion of hip dysplasia or if there is a parental concern of hip disease, a referral to a medical provider with expertise in medical and surgical management of newborn hip disease is strongly recommended. This provider can confirm physical examination findings, ensure that age-appropriate imaging is being performed, and begin treatment if necessary.
If the examination shows a stable hip but the baby has positive risk factors, then age-appropriate imaging is recommended. This can be ultrasonography at 6 weeks or an X-ray at 4 months. Of note is that the 2000 DDH clinical practice guideline recommends imaging of stable hips only for females born breech and not for other risk factors.3 Our recommendation to screen all infants with risk factors differs from the guidelines. This is an effort to make decisions regarding imaging simpler, more straightforward, and more uniform. For stable hips with acetabular dysplasia in children older than 6 weeks, the authors recommend treatment for patients in which the ultrasound shows an alpha angle less than 50 degrees and femoral head coverage less than 40%. If the ultrasound shows an alpha angle greater than 50 degrees and femoral head coverage above 40%, ultrasound should be repeated in 4 to 6 weeks because this mild dysplasia may represent normal physiologic variation and resolve spontaneously.19 Referral to a DDH specialist should be made if the follow-up ultrasound remains abnormal. For children 0 to 6 months, DDH Healio.com/Pediatrics | 233
CM E
Image courtesy of Wheaton Brace Company.
CM E
Figure 5. The recommended algorithm for neonatal screening of developmental dysplasia of the hip (DDH). Indications for ultrasonographic screening include instability on physical examination, a family history of DDH, and breech presentation. All ages are chronologic, not adjusted. AP = anteroposterior; FHC = femoral head coverage; PE = physical examination. (Adapted from Terjesen et al16 and Graf18)
Table 2.
Pavlik Treatment Success Severity of Dysplasia Based on PE
Success (%)
Stable
~100
Unstable - Barlow positive
>90
- Ortolani positive
64–93
Irreducible (Ortolani negative)
40
PE = physical examination. Adapted from Sucato et al;20 Viere et al;22 Hangen et al;23 Lerman et al;24 and Swaroop and Mubarak25
is treated with a Pavlik harness, and if older or larger, an abduction orthosis is used because the child can overpower the Pavlik harness. Again, the treatment of preterm infants should be based on chronologic age not adjusted age. The Pavlik harness is a dynamic splint that allows the infant to actively move its hips through a sphere of motion that encourages deepening and stabilization of the acetabulum (see Figure 6). The har234 | Healio.com/Pediatrics
ness is applied as soon as possible after the diagnosis of DDH requiring treatment is made and initially worn at all times. It is crucial to have staff available with time to teach as well as to provide take-home information for parents. This should allow the family to initially feel comfortable caring for the infant while in the brace and eventually feel confident in removing and reapplying the brace properly to allow bathing.
Figure 6. Proper fitting of the Pavlik harness is shown in a frontal view. The hips should be held in 90 degrees of flexion and neutral abduction/ adduction, with the straps then tightened. The infant should then sit in a relaxed position of flexion and abduction. Hyperflexion and hyperabduction are associated with femoral nerve palsy and femoral head osteonecrosis, respectively.
The length of treatment is dependent on the age at presentation and improvement of standard measurements on imaging. Progress is judged by serial physical examinations, static and/or dynamic ultrasonography, or serial AP pelvis Xray in patients older than 4 months. In the case of a frankly dislocated hip, Pavlik harness treatment is generally abandoned if no improvement is noted within 4 weeks of harness application. The success of Pavlik harness treatment is variable and correlates with the severity of the hip dysplasia. Treatment success is summarized in Table 2.20,22-25 Unfortunately, the use of a Pavlik harness is not without risks; excessive abduction of the patient’s hips can lead to avascular necrosis of the femoral head (in 0%–22%), and excessive flexion may result in femoral nerve palsy. Thus, proper position is critical with the hips abducted greater than 60 degrees when they are flexed to 90 degrees but with posterior straps lax enough to al-
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low the knees to be passively adducted to the midline26 (see Figure 6). A provider or orthotist experienced in Pavlik placement and instruction of the parents are crucial for the success of treatment while still ensuring safety. At our institution, we have patients return in a week to confirm adequate harness placement. If the hip is extremely unstable, we often recommend that parents keep the Pavlik on 24 hours per day until returning to the clinic in 1 week. It must be stressed that triple diapering is never an accepted form of treatment in DDH at any age. When a fixed dislocation is present or no improvement is made with Pavlik harness management after 4 weeks, closed reduction under general anesthesia with arthrographic evaluation and subsequent spica casting are attempted at 4 to 5 months (adjusted age for premature infants). For hips not amenable to closed reduction, open operative reduction of the hip with spica casting and often an adductor tendon tenotomy are required. Early, successful management reduces the risk for future operations such as pelvic osteotomies or early total hip replacement.2 Summary The diagnosis of DDH represents a spectrum of disorders that is common (ie, noted in about 1 of 100 newborns). In the newborn period, DDH is an asymptomatic condition and can be overlooked. All providers taking care of newborn children should know how to recognize DDH and when to refer these children for appropriate treatment. All newborns should be screened for DDH by physical examination. Early recognition of DDH is critical. Performing a careful physical examination, being aware of DDH risk factors, and obtaining appropriate and timely imaging are needed for this diag-
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nosis. Once the diagnosis is made, treatment for DDH is usually straightforward and generally successful. REFERENCES 1. Cooperman DR, Wallensten R, Stulberg SD. Acetabular dysplasia in the adult. Clin Orthop Relat Res. 1983;(175):79-85. 2. Wedge JH, Wasylenko MJ. The natural history of congenital disease of the hip. J Bone Joint Surg Br. 1979;61(3):334-338. 3. American Academy of Pediatrics. Clinical practice guideline: early detection of developmental dysplasia of the hip. Committee on Quality Improvement, Subcommittee on Developmental Dysplasia of the Hip. Pediatrics. 2000;105(4 Pt 1):896-905. 4. Guille JT, Pizzutillo PD, MacEwen GD. Development dysplasia of the hip from birth to six months. J Am Acad Orthop Surg. 2000;8(4):232-242. 5. Panagiotopoulou N, Bitar K, Hart WJ. The association between mode of delivery and developmental dysplasia of the hip in breech infants: a systematic review of 9 cohort studies. Acta Orthop Belg. 2012;78(6):697-702. 6. Hinderaker T, Daltveit AK, Irgens LM, Udén A, Reikerås O. The impact of intra-uterine factors on neonatal hip instability. An analysis of 1,059,479 children in Norway. Acta Orthop Scand. 1994;65(3):239-242. 7. Sionek A, Czubak J, Kornacka M, Grabowski B. Evaluation of risk factors in developmental dysplasia of the hip in children from multiple pregnancies: results of hip ultrasonography using Graf’s method. Ortop Traumatol Rehabil. 2008;10(2):115-130. 8. Bielski RJ, Gesell MW, Teng AL, Cooper DH, Muraskas JK. Orthopaedic implications of multiple gestation pregnancy with triplets. J Pediatr Orthop. 2006;26(1):129-131. 9. Dezateux C, Godward S. Evaluating the national screening programme for congenital dislocation of the hip. J Med Screen. 1995;2(4):200-206. 10. LeBel M-E, Gallien R. The surgical treatment of teratologic dislocation of the hip. J Pediatr Orthop B. 2005;14(5):331-336. 11. Jari S, Paton RW, Srinivasan MS. Unilateral limitation of abduction of the hip. A valuable clinical sign for DDH? J Bone Joint Surg Br. 2002;84(1):104-107. 12. Merck Manual of Diagnosis and Therapy. Porter R (ed). Hip, leg, and foot abnormalities Available at http://www.merckmanuals. com/professional/pediatrics/congenital_craniofacial_and_musculoskeletal_abnormalities/hip_leg_and_foot_abnormalities.
html?qt=galeazzi%20sign&alt=sh. Accessed Oct. 21, 2013. 13. Ortolani M. Un segno poco noto e sua importanza per la diagnosi precoce di prelussazione congenita dell’anca. Paediatria (Napoli). 1937;45:129. 14. Barlow TG. Early diagnosis and treatment of congenital dislocation of the hip. J Bone Joint Surg Br. 1962;44(2):292-301. 15. Bond CD, Hennrikus WL, DellaMaggiore ED. Prospective evaluation of newborn softtissue hip “clicks” with ultrasound. J Pediatr Orthop. 1997;17(2):199-201. 16. Terjesen T, Bredland T, Berg V. Ultrasound for hip assessment in the newborn. J Bone Joint Surg Br. 1989;71(5):767-773. 17. Clarke NM, Harcke HT, McHugh P, et al. Real-time ultrasound in the diagnosis of congenital dislocation and dysplasia of the hip. J Bone Joint Surg Br. 1985;67(3):406-412. 18. Graf R. Fundamentals of sonographic diagnosis of infant hip dysplasia. J Pediatr Orthop. 1984;4(6):735-740. 19. Marks DS, Clegg J, al-Chalabi AN. Routine ultrasound screening for neonatal hip instability. Can it abolish late-presenting congenital dislocation of the hip? J Bone Joint Surg Br. 1994;76(4):534-538. 20. Sucato DJ, Johnston CE 2nd, Birch JG, Herring JA, Mack P. Outcome of ultrasonographic hip abnormalities in clinically stable hips. J Pediatr Orthop. 1999;19(6):754–759. 21. Bick U, Müller-Leisse C, Tröger J. Ultrasonography of the hip in preterm neonates. Pediatr Radiol. 1990;20(5):331-333. 22. Viere RG, Birch JG, Herring JA, Roach JW, Johnston CE. Use of the Pavlik harness in congenital dislocation of the hip. An analysis of failures of treatment. J Bone Joint Surg Am. 1990;72(2):238-244. 23. Hangen DH, Kasser JR, Emans JB, Millis MB. The Pavlik harness and developmental dysplasia of the hip: has ultrasound changed treatment patterns? J Pediatr Orthop. 1995;15(6):729-735. 24. Lerman JA, Emans JB, Millis MB, et al. Early failure of Pavlik harness treatment for developmental hip dysplasia: clinical and ultrasound predictors. J Pediatr Orthop. 2001;21(3):348-353. 25. Swaroop VT, Mubarak SJ. Difficult-to-treat Ortolani-positive hip: improved success with new treatment protocol. J Pediatr Orthop. 2009;29(3):224-230. 26. Kitoh H, Kawasumi M, Ishiguro N. Predictive factors for unsuccessful treatment of developmental dysplasia of the hip by the Pavlik harness. J Pediatr Orthop. 2009;29(6):552-557.
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