Scott Yang, MD,a​ Natalie Zusman, MD,​a Elizabeth Lieberman, MD,​a Rachel Y. Goldstein, MDb

Developmental Dysplasiaabstract of the Hip

Pediatricians are often the first to identify developmental dysplasia of the hip (DDH) and direct subsequent appropriate treatment. The general treatment principle of DDH is to obtain and maintain a concentric reduction of the femoral head in the acetabulum. Achieving this goal can range from less-invasive bracing treatments to more-invasive surgical treatment depending on the age and complexity of the dysplasia. In this review, we summarize the current trends and treatment principles in the diagnosis and treatment of DDH.

Developmental dysplasia of the hip infancy and early childhood to prevent (DDH) encompasses a broad spectrum subsequent functional impairment. of abnormal hip development during A variety of methods are available infancy and early development. achieve the overarching goal of The definition encompasses a aDepartment of Orthopedics and Rehabilitation, obtaining a concentric hip reduction. Doernbecher Children’s Hospital and Oregon Health and wide range of severity, from mild b The treatment methods and goals Science University, Portland, Oregon; and Children’s acetabular dysplasia without hip Orthopaedic Center, Children’s Hospital Los Angeles, Los have not drastically changed in Angeles, California dislocation to frank hip dislocation. the past 20 years, although recent The etiology of DDH is multifactorial. developments within the past 5 to 10 Dr Yang conceptualized and drafted the initial Risk factors for DDH are breech years have been focused on optimal manuscript and edited the final manuscript; positioning in utero, female sex, Drs Zusman and Lieberman drafted the initial – surveillance methods, imaging manuscript; Dr Goldstein provided content guidance being firstborn,1 4 and positive family modalities to guide treatment, and edited and provided critical revisions to the history. ‍‍ Other conditions related outcomes assessment of treatment manuscript; and all authors approved the final to prenatal positioning, including methods, and refining indications for manuscript as submitted. metatarsus adductus and torticollis, treatment. It is important for both the DOI: https://​doi.​org/​10.​1542/​peds.​2018-​1147 are associated with DDH. Prolonged clinicians and families to understand Accepted for publication Sep 7, 2018 abnormal postnatal positioning via that the treatment of a dysplastic Address correspondence to Scott Yang, MD, swaddling also has been suggested as hip can be challenging and met with Department of Orthopedics and Rehabilitation, a risk factor in DDH because certain complications. Doernbecher Children’s Hospital, 3181 SW Sam ethnic populations that practice Jackson Park Rd, Mail Code CDW6, Portland, OR Although variations in treatment 97239. E-mail: [email protected] tight swaddling have a higher rate 5,6​ exist based on individual patient of DDH. ‍ The treatment algorithm PEDIATRICS (ISSN Numbers: Print, 0031-4005; Online, ’ characteristics, the following algorithm 1098-4275). in patients with DDH depends on is generally considered (Table 1). each patient s age and severity of the Copyright © 2019 by the American Academy of Infants up to 6 months of age who Pediatrics condition. The goal in the treatment are confirmed to have hip instability FINANCIAL DISCLOSURE: The authors have of DDH is to achieve and maintain a or dislocation are generally treated indicated they have no financial relationships concentric reduction of the femoral with a brace initially, such as a Pavlik relevant to this article to disclose. head in the acetabulum to allow for harness or abduction orthosis. Patients FUNDING: No external funding. continued normal development of the aged 6 to 18 months with dislocation POTENTIAL CONFLICT OF INTEREST: The authors hip. The natural history of residual can be treated with closed reduction have indicated they have no potential conflicts of DDH or dislocation into adulthood and the application of a hip spica cast. interest to disclose. has been associated with pain and Generally, patients >12 to 18 months early development of osteoarthritis. of age or those who fail to achieve a To cite: Yang S, Zusman N, Lieberman E, et al. Residual sequelae of DDH are 1 concentric hip reduction with closed Developmental Dysplasia of the Hip. Pediatrics. 2019;143(1):e20181147 of the leading causes of early7 hip methods are considered candidates osteoarthritis in adulthood. Hence, the for open surgical hip reduction. There goal is to improve hip development in are outliers to this general algorithm Downloaded from www.aappublications.org/news by guest on September 26, 2021 PEDIATRICS Volume 143, number 1, January 2019:e20181147 STATE-OF-THE-ART REVIEW ARTICLE TABLE 1 General Treatment Algorithm for Hip Dislocation Age Treatment Comments <6 mo Abduction orthosis (ie, Pavlik harness) — 6–18 mo Closed reduction under general anesthesia with hip spica cast Closed reduction at <6 mo of age if abduction orthosis attempt fails >12–18 mo Open hip reduction Open reduction <1 y of age if previous closed-reduction attempt fails >2 y Open hip reduction with or without femoral shortening osteotomy Femoral shortening osteotomy may, but not always, be needed on the basis of the amount of tension that needs to be relieved to achieve a hip reduction. 3–8 y Open hip reduction with or without femoral shortening osteotomy and Pelvic osteotomy may, but not always, be needed to address residual with or without pelvic osteotomy acetabular dysplasia. >8 y Open hip reduction versus observation for eventual arthroplasty Controversial; poorer outcomes noted in attempting hip open reductions in those >8 y old

because children <6 months old abducting the hips while applying may occasionally require closed anterior-directed pressure at the or open hip reduction if bracing greater trochanters. An Ortolani treatment fails. Osteotomies, such as maneuver is considered to have a femoral shortening osteotomy and positive result if the femoral head pelvic osteotomy, are considered relocates with a distinct clunk. An for hip dislocation in older patients Ortolani-positive hip is more severe to decrease tension on the hip than a Barlow-positive hip because reduction and those with a residual it indicates that the femoral head is shallow dysplastic acetabulum, dislocated at rest. The presence of a respectively. Adolescents and young subtler hip click during examination FIGURE 1 adults with residual symptomatic is a nonspecific finding and often 9,10​ Galeazzi sign. With the pelvis level on a flat acetabular dysplasia are treated does not indicate true hip pathology. ‍ surface, the heights of the knees are asymmetric. with periacetabular osteotomy The 2 major limitations of these The right knee height is shorter, suggesting possible hip dislocation. (PAO) to preserve the native hip maneuvers are their dependence on joint and avoid hip arthroplasty. the skill of the examining provider Recent developments in each of these and the fact that these tests are more treatment methods will be discussed sensitive in younger infants, whose thigh folds and clinical examination in this article. soft tissues around the hip joint of limb length discrepancy are prone HIP EXAMINATION have yet to contract. Furthermore, to error and inaccuracy. The most a severely dislocated hip that is not sensitive examination for unilateral reducible may not have a Barlow hip dislocation in a child >3 months or Ortolani positive result. The old is an assessment for asymmetric Early identification of infants with 12,13​ sensitivity of Barlow and Ortolani diminished hip abduction (Fig 2). ‍ dysplastic hips can be performed on examination maneuvers alone in 11 The walking child may also present a routine basis from the newborn identifying DDH is at best 54%‍ ; physical examination and continue with a Trendelenburg gait (trunk tilt ’ 8 thus, adjunct imaging modalities for toward the affected hip when weight until the child reaches walking age. identification can be helpful. A newborn infant s hips should is applied) if there is a unilateral be evaluated by using the Barlow For the older infant or child, dislocation or a waddling gait (trunk and Ortolani physical examination Barlow and Ortolani examination tilt toward the weight-bearing side, maneuvers. The Barlow maneuver is of limited utility due to the alternating throughout the gait is performed by adducting the hip development of contractures. These cycle) if there is bilateral dislocation. to the midline and gently applying patients are observed for leg length For infants who are Ortolani- posterior force. A positive Barlow discrepancy, thigh-fold asymmetry, positive or older children with any result is when the femoral head and limited hip abduction. Leg length of the above examination findings, subluxes, and a clunk is felt. A discrepancy should be assessed for further diagnostic evaluation can be Barlow-positive hip indicates that with the infant in the supine position obtained, as described below. ° the femoral head is resting in the with the pelvis flat on a level surface DIAGNOSTICS: IMAGING STUDIES acetabulum but has pathologic and the hips and knees flexed to 90 . instability. With the thighs adducted A discrepancy is indicated by unequal and posteriorly depressed, the knee heights, which is termed the Ultrasonography is the recommended Ortolani maneuver is performed by Galeazzi sign (Fig 1). Asymmetric imaging modality in infants <4 Downloaded from www.aappublications.org/news by guest on September 26, 2021 2 YANG et al maturation, these early pathologic findings often resolve spontaneously with time. Previously, the US Preventive Services Task Force published a report in 2006 in which it concluded FIGURE 2 that there was insufficient evidence The right hip has limited abduction compared to support routine screening for with the left, suggesting possible hip dislocation. DDH in infants to prevent14 future adverse outcomes. However, this recommendation was met with controversy because DDH is months old because the infant hip difficult to identify without a focused is predominantly cartilaginous, examination, can lead to significant precluding clear radiographic FIGURE 3 disability if left untreated, and is Coronal ultrasound images of a 2-month-old visualization. Ultrasonography more easily treated at a young age dysplastic hip. Key ultrasound measurements during infancy. Subsequently, the allows for the visualization of the include the (which is formed by the bony α American Academy of Pediatrics femoral head location relative to the ilium and the bony roof of the acetabulum), the (AAP) recommends continuing acetabulum and specific anatomic β angle (which is formed by the bony ilium and the labral fibrocartilage), and the percentage periodic newborn physical parameters, such as the depth of of the femoral head covered by the bony roof of examination surveillance throughout the acetabulum and inclination of the acetabulum. The α angle has more clinical infancy. the acetabular roof. Key ultrasound significance than theβ angle. In this image, (1) the femoral head does not seat deeply in measures are depicted in Fig 3. The the socket, with <50% of the femoral head Controversy exists as to what imaging modality can be performed being covered by the acetabulum, and (2) the is the best screening method. in a static or dynamic manner. In a acetabulum is shallow (normal α >60°). Several methods include physical static study, researchers examine examination alone, physical the joint anatomy (ie, the shapes and EARLY IDENTIFICATION AND examination with a selective use relations between the femoral head, SURVEILLANCE of ultrasonography, and universal acetabulum, and labrum). During a screening with ultrasonography. dynamic ultrasonography, hip joint There has been no comparative study stability is assessed by performing The optimal method to screen for of outcomes in patients who have the manipulative stress maneuvers DDH is controversial. The goal of not been screened versus those who under direct imaging observation. screening in DDH is to both prevent underwent a screening program undiagnosed cases and allow for for DDH. Ultrasonography has been Ultrasonography can be used for earlier, less-aggressive interventions demonstrated to be used to identify both initial infant screening of DDH to achieve hip reduction. One potentially pathologic hips more than and monitoring of patients with difficulty with screening DDH is clinical examination alone. Dezateux DDH undergoing active treatment. 15 that there is no uniform pathology and Rosendahl reported that the The femoral head ossification ∼ that characterizes DDH because identification of dysplastic hips in nucleus is visible radiographically the definition encompasses mild general populations increased from at 4 to 6 months of age. Hence, acetabular dysplasia to frank 1.6 to 28.5 per 1000 infants, with radiographs are not recommended ∼ dislocation. Although the early clinical examination increasing from for DDH evaluations before 4 natural history is more clearly 34.0 to 60.3 per 1000 infants with months of age. After 6 months of understood in cases of untreated the use of screening ultrasonography. age, radiographs are the preferred hip dislocation, the long-term Studies in which researchers method of evaluating and monitoring history of mild acetabular dysplasia compare clinical examination DDH after femoral head ossification identified with ultrasound in and selective ultrasonography more reliably appears. It is important infancy is unclear. The normal to universal ultrasonography to note that the affected hip in immature hip can demonstrate revealed no significant difference in DDH often demonstrates a delayed instability, such as a Barlow-positive decreasing16,17​ the late presentation of radiographic appearance of the examination result or dynamic DDH. ‍ A 2013 Cochrane Review on femoral head ossification center. Key ultrasonography evidence instability, the topic echoed this conclusion with radiographic measures and angles due to ligamentous laxity during the the findings that targeted screening are depicted in Fig 4. early neonatal period. With normal is not associated with significant Downloaded from www.aappublications.org/news by guest on September 26, 2021 PEDIATRICS Volume 143, number 1, January 2019 3 result) while initially observing milder instability (Barlow- positive test result). Targeted ultrasonography evaluation of infants 6 weeks to 6 months old can be obtained on the basis of consultation with a pediatric radiologist or orthopedist, although universal ultrasonography screening is not routinely recommended. On whom to obtain an ultrasound can be further elucidated in the American Academy of Orthopaedic Surgeons clinical practice guidelines. This report included a moderate recommendation for performing a screening imaging study for infants <6 months old with 1 or more of the significant risk factors: breech

position, history of clinical instability,19 and positive family history. Finally, in the AAP guidelines, the authors state that parents should FIGURE 4 avoid tight swaddling of the lower AP pelvis radiograph of a left-hip dislocation. On an AP pelvis radiograph, classic measurements extremities that places the hips into include drawing several lines to help identify dysplasia. H is drawn as a horizontal line, connecting adduction to minimize the risk of the bilateral acetabular triradiate cartilage. P is then drawn perpendicular to H at the lateral edge of the acetabulum. In the normal right hip, the ossific nucleus rests along the bottom-inner quadrant DDH. Tight swaddling can lead to formed by the intersection of the 2 lines. In the dislocated hip, the ossific nucleus rests lateral to the excess prolonged stress on the hips, intersection of the 2 lines. S should reveal a smooth arch from the obturator foramen to the inferior leading to instability. Thus, the AAP aspect of the femoral neck, as in the right hip. S is disrupted on the left hip, suggesting dislocation. and Pediatric Orthopaedic Society The acetabular index is the angle formed along the acetabular roof and H, with steeper values indicating acetabular dysplasia. Notice also that the left femoral head ossific nucleus is smaller, of North America recommend that and its appearance is more delayed compared with the nondysplastic side. AI, acetabular index; AP, infant hips should have freedom anteroposterior; H, Hilgenreiner line; P, Perkins line; S, arc of Shenton. of flexion and22 abduction during swaddling. EARLY BRACE MANAGEMENT 20 increases in late diagnoses when on serial21 ultrasonography. Olsen et al identified that adding universal compared with universal screening – ultrasound to clinical screening and is associated with a reduction18 For infants up to 6 months of age, the in potential overtreatment. The doubled the early brace treatment Pavlik harness (Fig 5) has classically American Academy of Orthopaedic rate without a significant decrease in been used for the stabilization of the Surgeons also provided a moderate- late-presenting DDH. dysplastic hip. The Pavlik harness is strength recommendation supporting The AAP has recently published a used to hold the hips in a position of not performing universal screening best practice clinical report8 based flexion and abduction that allows for ultrasound in newborns in its 19 on best available evidence. These the centering of the femoral head in recent clinical practice guideline. guidelines include a healthy balance the acetabulum. Recent studies on Because many milder forms of DDH of adequate identification and the use of the Pavlik harness help have a benign natural history, this prevention of overtreatment in mild us understand which patients have increased identification of DDH can forms of DDH. Key recommendations successful outcomes and those who potentially lead to overtreatment. include that routine newborn and are at risk for failure of harness The true natural history of mild periodic physical examinations treatment. The Barlow-positive acetabular dysplasia on a well- should be performed by pediatricians hip has been demonstrated to have located hip on ultrasonography is to clinically detect DDH. Evidence >90%‍ successful stabilization with unclear because many can improve is used to support treating hip a Pavlik harness. The Ortolani- without intervention, as evidenced dislocation (Ortolani-positive test positive, or initially dislocated, hip Downloaded from www.aappublications.org/news by guest on September 26, 2021 4 YANG et al is more problematic– and has had

Pavlik harness failure23 25 in 21%‍ to 37%‍ of patients. ‍‍ Patient-related risk factors for failure of harness treatment included increased age at initiation25, of26​ treatment (>7 weeks27 old),​ ‍ multigravida birth,​ the27 presence of a foot24 deformity,​ and male sex. The initial ultrasonographic severity of dysplasia in the Ortolani-positive hip is prognostic for the failure of Pavlik harness treatment, with more severely dislocated hips in which the labrum is interposed between the femoral head and acetabulum23 being associated with failure. FIGURE 5 Pavlik harness on an infant, gently holding the hips in a flexed and abducted position. For those patients with an Ortolani- positive hip who fail to stabilize after initial Pavlik harness treatment, authors of recent literature suggest that a trial of a more rigid abduction hip orthosis, such as an Ilfeld orthosis (Fig 6), may obviate the need for either closed or open reduction in28 the operating room. Sankar et al demonstrated that a stable hip reduction was achieved in 82%‍ of patients who underwent rigid orthosis treatment after Pavlik harness failure in Ortolani-positive hips, with equivalent radiographic outcomes to closed reduction and casting being observed. Rigid abduction orthotic management allows for an alternative pathway to avoiding general anesthesia and casting in young children. Complications of the Pavlik harness or abduction orthoses are rare, although they can include avascular necrosis (AVN) of the femoral head, skin irritation, and femoral nerve palsy. Femoral nerve palsy is apparent when the infant stops demonstrating spontaneous knee extension while in the Pavlik harness. FIGURE 6 Ilfeld abduction orthosis on a patient. This orthosis allows for the hips to be held more rigidly in In a recent study, researchers abduction than a Pavlik harness. compiled cases of femoral nerve palsy with Pavlik harness treatment and demonstrated that all patients recovered nerve function after the importantly, patients who developed treatment, possibly indicating that discontinuation or loosening29 of femoral nerve palsy had a high this complication occurs in more the Pavlik harness straps. More (47%‍) failure rate of Pavlik harness severe cases of DDH or that the Downloaded from www.aappublications.org/news by guest on September 26, 2021 PEDIATRICS Volume 143, number 1, January 2019 5 cessation of harness due to nerve have been recently studied, including femoral head after casting. In 1 study, palsy contributed to the failures. age, radiographic presence of the no patients with a normal perfusion

ossific nucleus, and abduction MRI result41 after casting developed For patients who underwent angle in the cast. A prospective AVN. This modality is promising successful treatment with the study revealed that AVN occurs in and theoretically allows for checking Pavlik harness, researchers in up to 25%‍ of patients after closed33 the perfusion of the femoral heads several studies elucidate which reduction and casting of the hip. and the correction of excessive hip patients need further radiographic A major current focus among pediatric abduction in the cast before the monitoring for residual acetabular orthopedic surgeons is on minimizing development of permanent femoral dysplasia. Patients with initial severe this complication. Previously, the head ischemia. ultrasonographic hip dislocations presence of a radiographic ossific ∼ – are associated with abnormal nucleus (which usually appears at Generally, in patients >12 to 18 radiographic acetabular development 4 6 months old in normal hips) months of age or younger patients at 1 year of age and may need further and older age were regarded as who failed closed reduction, an open radiographic 30monitoring throughout protective from developing AVN, surgical approach is recommended to their growth. However, patients with the theory being that the remove anatomic blocks to achieving with normal radiographic acetabular cartilaginous femoral head is more a concentric hip reduction. Recent development by age 2 years after susceptible to ischemic34,35​ damage advancements in open reduction are successful Pavlik harness treatment from pressure. ‍ These claims similarly focused on understanding have all demonstrated continued ’ remain controversial, with more risk factors for developing surgical normal acetabular development recent literature revealing no such complications. Open reduction can at a mean of 10 years follow-up, association, and thus no clear benefit be performed via an anterior- or suggesting that further radiographic in waiting– until ossification of the medial-based surgical approach surveillance after a normal femoral36 38 head occurs to reduce the to the hip. The medial approach is radiograph31 result at age 2 years is not hip. ‍ Traction applied to the less invasive and does not require necessary. lower extremity to facilitate a gradual splitting the iliac apophysis. The HIP REDUCTION stretching of the contracted tissues of anterior approach is more classic the hip has previously been thought and allows for more comprehensive to reduce the risk of AVN via a more access to the acetabulum and the – gentle, graduated correction than a barriers to reduction. Furthermore, a In older infants with untreated hip closed reduction39 without traction. capsulorrhaphy (surgically tightening dislocations (generally 6 18 months) Sucato et al recently reported the hip capsule to maintain hip or those who failed early brace their findings on the largest series of stability) is only possible with an treatment of hip stabilization, closed traction used before hip reduction anterior approach. Proponents of reduction and hip spica casting is for dislocated hips in those <3 years either surgical approach may cite a next in the treatment algorithm. The of age and demonstrated no major decreased risk of AVN as the main technique or indication for closed difference in successful closed indication of choosing 1 over the reduction has not significantly reduction and AVN rates in patients other, although no researchers have changed over time, yet our who were treated with traction conclusively demonstrated that understanding of the outcomes of compared with those who were 1 approach is more prone to the the procedure continues to expand. not. Hence, traction is not routinely development of AVN. The surgical Closed reduction is performed ° ° recommended because of caregiver approach of choice seems to depend under general anesthesia, the hip is and potential patient burden without mostly on surgeon comfort level. placed in 90 to 100 of flexion, and a clear benefit in outcome. It is AVN rates for either approach in the the minimal amount of abduction thought that excessive abduction literature vary widely depending ∼ necessary to maintain a stable hip of the hip leads to increased on the study, although pooled meta- reduction is sustained. Failure of pressure on the femoral head and analysis data reveal a 20%‍ AVN reduction or redislocation32 can occur subsequently to impaired perfusion40 rate42 for open-reduction surgery (Fig in up to 13.6%‍ of cases. of the femoral head. Schur et al 7). For older patients (generally AVN of the femoral head and the demonstrated an up to 60%‍ AVN rate >2 years), a femoral shortening associated proximal femoral growth in patients <6 months of age if the hip ° osteotomy can be added to the open- disturbance is the most feared abduction in the hip spica cast was reduction surgery to reduce tension and frequent complication of this >50 . Newer contrast perfusion MRI on the long-standing contracted procedure. Several etiologies and protocols have been used in some dislocated hip and has been shown risk factors for this complication centers to evaluate perfusion of the to be beneficial in reducing AVN Downloaded from www.aappublications.org/news by guest on September 26, 2021 6 YANG et al 43 and redislocation rates. The upper age limit when performing an open reduction of a dislocated hip is unclear. Recent literature reveals that younger children (<8 years) may benefit the most from the relocation of long-standing hip dislocation. Late-diagnosed hip dislocations after age 8 years tend to do more poorly with open reduction of the hip, and whether to perform a reduction in44, 45​ these patients is highly debatable. Pelvic Osteotomies

Acetabular dysplasia is usually characterized by a shallow and/or vertically oriented acetabulum. This leads to either inadequate coverage to contain the femoral head in a reduced position or acceleration of arthritis due to abnormal edge contact loading. In patients who have failed initial treatment and have persistent acetabular dysplasia, pelvic osteotomies may be indicated to resume a more normal development of the acetabulum. These surgeries are usually reserved for older children because the acetabulum has been shown to remodel throughout46 childhood up to age 5 years,​ allowing for continued development in the presence of a well-located hip. Hence, the timing of performing the ∼ osteotomy is controversial although typically performed at 3 to 5 years of age for residual acetabular FIGURE 7 dysplasia. The most commonly used A 5-year-old girl, 2 years after right-hip open reduction, who underwent femoral and pelvic osteotomy, pelvic osteotomies are termed the with the development of femoral head fragmentation and irregularity suggestive of AVN. Salter, Pemberton, and Dega. All these osteotomies use a single cut above the acetabulum, with their differences being in the completion to achieve adequate acetabular the acetabular and the achievement or direction of the cut (Fig 8). On the coverage of the dysplastic hip with of increased correction of acetabular basis of recently available literature, a single osteotomy with increasing dysplasia (Figs 9 and 10). the radiographic and clinical age. For older children with an At this juncture, it appears that outcomes for which researchers open triradiate cartilage growth pelvic osteotomies are useful in compare the various types of center, typically >6 years of age, a improving radiographic coverage osteotomy appear– to be similar in triple innominate osteotomy can be of the femoral head and preventing the treatment of residual acetabular considered. In the triple innominate 47–50 reoperation for residual instability dysplasia. ‍‍ Although there is no osteotomy, all 3 osseous regions after open reduction. The technique clear upper age limit guideline to the surrounding the acetabulum are cut of osteotomy appears to be at the above osteotomies, it is more difficult to allow for a free reorientation of discretion of the surgeon because 1 Downloaded from www.aappublications.org/news by guest on September 26, 2021 PEDIATRICS Volume 143, number 1, January 2019 7 FIGURE 9 Lateral view of the pelvis, with the 3 characteristic osteotomies surrounding the acetabulum in a triple innominate osteotomy.

FIGURE 8 Schematic of the differences between Salter, Dega, and Pemberton osteotomies.

technique has not been definitively PAOsproven for to Adolescents be superior to another.

There has been recent momentum in the field of adolescent and young adult hip preservation surgery, with the goal being preventing degenerative osteoarthritis related to DDH. The Bernese PAO is a technique developed in Switzerland and has FIGURE 10 gained popularity over the past A, A 10-year-old skeletally immature girl with bilateral hip dysplasia with deficient coverage of several decades. In this osteotomy, bilateral femoral heads. B, Four months’ status after left triple innominate osteotomy with improved specific cuts are made around the coverage of the left femoral head. acetabulum to allow for a complete reorientation of the acetabular cartilage while maintaining an intact posterior column and without The current indications for patients are in refining patient selection as causing any structural changes to to undergo PAO include young to who can most benefit from the the intrapelvic space (Fig 11). The patients with hip pain who have a goal in an osteotomy is to realign procedure. Although a strict age closed triradiate acetabular cartilage the native acetabulum to allow cutoff for the procedure is not well growth center, radiographic evidence for improved acetabular coverage defined, poorer outcomes after PAO of femoral head uncoverage due to a of the femoral head (Figs 12 and have been associated51 in patients 13). This theoretically improves shallow acetabulum, and a congruent aged >35 years. To optimize patient abnormal contact forces of the hip hip joint without radiographic signs selection, several centers have that predispose the hip to early of arthritic degeneration. The recent been using a delayed gadolinium- degenerative osteoarthritis and early developments in adolescent and enhanced MRI of cartilage protocol hip arthroplasty. young adult hip preservation surgery preoperatively to specifically Downloaded from www.aappublications.org/news by guest on September 26, 2021 8 YANG et al FIGURE 11 Lateral view of the pelvis, with the characteristic osteotomies surrounding the acetabulum in PAO. The posterior column of the acetabulum is preserved, which differs from a triple innominate osteotomy.

FIGURE 12 A 17-year-old skeletally mature girl with bilateral hip pain and dysplasia with deficient coverage of bilateral femoral heads. evaluate early cartilage degeneration that is not detected52,53​ by using routine radiography. ‍ This tool can be helpful in selecting patients without cartilage degeneration who can benefit most from PAO.

Early-term and midterm outcomes of PAOs have been favorable in appropriately selected adolescents or young-adult patients. Most patients demonstrate improved hip pain symptoms after PAO. A detailed evaluation of patient-reported outcomes in the short-term revealed significant improvement in quality of life,54 pain, and function after PAO. More modest improvements in patient-related outcomes after surgery are associated with patients with milder 54radiographic DDH and obesity. The PAO appears to have an excellent result in the intermediate term. Several studies revealed that 93%‍ to 95%‍ of young – FIGURE 13 patients undergoing PAO (mean ’ (Continued) Six months’ status after right PAO with improved coverage of the right femoral head. age: 25.4 26 years) did not require a hip replacement55,56​ at 10 years follow-up. ‍ There is a paucity ’ of long-term follow-up of PAO. The progress to develop pain symptoms, this sample did not represent a strict only long-term study of >30 years have radiographic evidence of selection criterion for surgery that is follow-up revealed that as many osteoarthritis, or require57 hip often used today because advanced as 71%‍ of patients continued to replacement after PAO. However, osteoarthritis was present in 24%‍ Downloaded from www.aappublications.org/news by guest on September 26, 2021 PEDIATRICS Volume 143, number 1, January 2019 9 JW. Familial predisposition to 16. Holen KJ, Tegnander A, Bredland T, et al. developmental dysplasia of the hip. Universal or selective screening of of the hips before PAO in the study. J Pediatr Orthop. 2009;29(5): the neonatal hip using ultrasound? A More time will be required to truly 463–466 prospective, randomised trial of 15,​529 appreciate the long-term benefit of 5. Rabin DL, Barnett CR, Arnold WD, newborn infants. J Bone Joint Surg Br. the PAO procedure. Freiberger RH, Brooks G. 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Evid Based Child treatment, and refine the selection of 1984;(184):34–40 Health. 2013;8(1):11–54 patients who can best benefit from 7. Harris WH. Etiology of osteoarthritis 19. Mulpuri K, Song KM, Goldberg hip preservation surgery. The ideal of the hip. Clin Orthop Relat Res. MJ, Sevarino K. Detection and continued target would be to prevent 1986;(213):20–33 nonoperative management of pediatric missed hip dislocations or dysplasia 8. Shaw BA, Segal LS; Section on developmental dysplasia of the hip during the infant period, prevent AVN Orthopaedics. Evaluation and in infants up to six months of age. during early treatment, and decrease referral for developmental dysplasia J Am Acad Orthop Surg. 2015;23(3): the incidence of total hip arthroplasty of the hip in infants. Pediatrics. 202–205 in adulthood related to undertreated 2016;138(6):e20163107 20. Rosendahl K, Dezateux C, Fosse KR, DDH. 9. Jones DA. Importance of the clicking et al. 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Downloaded from www.aappublications.org/news by guest on September 26, 2021 Developmental Dysplasia of the Hip Scott Yang, Natalie Zusman, Elizabeth Lieberman and Rachel Y. Goldstein Pediatrics 2019;143; DOI: 10.1542/peds.2018-1147 originally published online December 26, 2018;

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