Pediatrics

Developmental dysplasia of the hip

OVERVIEW: What every practitioner needs to know

Are you sure your patient has developmental dysplasia of the hip? What are the typical findings for this disease?

The diagnosis of developmental dysplasia of the hip (DDH) can usually be made in the newborn based on finding an unstable hip on physical examination. Stress examination by the Barlow stress test (adduction and posterior force) will dislocate a dysplastic hip posteriorly from the acetabulum and the Ortolani stress (abduction and anterior force) test will relocate a posteriorly dislocated dysplastic hip. Positive stress examination with a palpable dislocation or reduction of the hip is confirmatory for DDH. Audible or palpable "clicks" are common in the newborn and are not indicative of DDH.

Other common findings in the newborn include limited abduction of hips, limb length inequality, positive Galeazzi sign (different levels of the knee with the hip flexed in the supine position), and asymmetry of thigh creases. Positive findings are suggestive but not diagnostic for DDH.

The child of walking age with undiagnosed unilateral DDH may present with frank limb length inequality, toe walking, or a limp. Bilateral DDH can be difficult to diagnose clinically because abduction is often symmetric and there is no limb length difference. Patients may present with excessive lumbar lordosis and a waddling gait.

How do you perform a hip examination in a newborn/infant?

A calm and content infant is required to perform a good hip examination. Make sure the child is not hungry. Often nursing or a bottle just before examination is helpful in relaxing the infant. Dimming the lights may also be beneficial. A pacifier or parent's finger can engage the calming sucking reflex. Sugar-sweetened water on the pacifier or the parent's finger is often helpful. Clothing and diaper should be removed for the examination.

The child should be supine. Grip both hips lightly from the outside with the index or long finger over the greater trochanter and the thumb on the medial thigh. A common error is to grasp the legs too tightly. Do not grip firmly, this will only irritate the child and lead to muscle guarding and an unreliable examination. Stress each hip individually. Stabilize the pelvis by holding one hip and then alternate between the Barlow and Ortolani maneuvers.

The Barlow maneuver involves adduction and posterior pressure on the inner upper thigh to dislocate a reduced hip. The Ortolani maneuver involves abduction and anterior force on the greater trochanter to reduce a dislocated hip.

Move smoothly and gently between maneuvers. Alternate from side to side. The palpable dislocation or reduction may not occur or be evident every time. Be patient and repeat the maneuvers several times before confirming a normal or abnormal examination. A hip may be normal for several repeated iterations before it dislocates or reduces.

Once you are comfortable with your stress examination, assess abduction. In newborns, with the hips flexed to 90 degrees, both hips should abduct symmetrically almost all the way to the examination table. Flex the hips to 90 degrees and evaluate knee height from the foot of the table. Uneven heights represent a positive Galeazzi sign and are suggestive of DDH.

Finally, assess the Klisic sign. Place your long finger on the greater trochanter and index finger on the anterior superior iliac spine. An imaginary line connecting these two points should pass through or above the umbilicus. If it passes below the umbilicus, it may indicate a high greater trochanter associated with DDH and proximal position of the dislocated hip. Observe the gluteal and thigh creases; asymmetry can be a sign of DDH but is often a normal variant.

What other disease/condition shares some of these symptoms?

Audible or palpable "clicks" are often appreciated and are not clinically significant. They represent normal soft tissue such as the ligamentum teres, psoas tendon, or fascia lata moving over bony prominences.

No condition other than DDH will lead to frank instability with a positive Barlow or Ortolani test result.

What caused this disease to develop at this time?

The common cause of DDH is excessive laxity of the hip joint capsule. This can be intrinsic laxity of the capsule or may develop because of abnormal fetal positioning.

Fetal response to relaxin, a maternal hormone, is stronger in girls. Fetal response to relaxin can lead to laxity in the hip capsule, and the increased response in girls may explain the increased incidence of DDH in female infants.

Breech positioning is known to be a strong risk factor for DDH. Frank breech with knees extended has the highest risk of DDH, up to 20%. Overall, breech positioning carries a risk of DDH between 5% and 15% in most reported series.

First-born children have a higher incidence of DDH compared with later children. This is believed to be due to tighter positioning in the uterus of first-time mothers.

Diminished amniotic fluid (oligohydramnios) also is associated with DDH and is also likely due to tighter positioning in utero. Other conditions associated with tight intrauterine positioning, including torticollis and metatarsus adductus, are also associated with DDH.

Certain syndromes with soft tissue laxity or abnormal joint positioning are also associated with DDH. These include arthrogryposis, Down syndrome, Larsen syndrome, Ehlers-Danlos syndrome, and other connective tissue disorders.

What laboratory studies should you request to help confirm the diagnosis? How should you interpret the results?

No laboratory studies are useful in the diagnosis of DDH.

Would imaging studies be helpful? If so, which ones?

Ultrasonography is the preferred imaging modality for DDH in newborns and infants. The acetabulum and femoral head are predominantly cartilage and are not visible on radiographs. Ultrasonography allows visualization of these structures, as well as the labrum. Ultrasonography also allows for dynamic evaluation of hip position and stability through the use of stress maneuvers.

Ultrasonography is ideal while the femoral head remains unossified. It can generally be used as a primary imaging modality until at least 6 months, and often further up to 9 months, depending on extent of ossification. As the femoral head ossifies, ultrasonography becomes less helpful because of scatter of the ultrasonic waves.

Radiographs become more helpful as children age. They may be considered for evaluation of DDH after the age of 3-4 months; however, in general they are not as useful as ultrasonography until ossification of the femoral head, which usually occurs between 6 and 9 months (See Figure 1 and Figure 2).

Figure 1.

Normal hip seen on ultrasonogram

Figure 2.

Ultrasound of dislocated hip

Confirming the diagnosis

The American Academy of Pediatrics (AAP) developed clinical practice guidelines for early detection of DDH. Each recommendation is detailed with level of evidence.

These recommendations have been endorsed by the Pediatric Orthopaedic Society of North America.

Recommendations were made for:

All newborns to be screened by physical examination.

If a positive Ortolani or Barlow sign is identified in the newborn, referral to an orthopedist is recommended by the age of 2 weeks.

If a newborn has positive Ortolani or Barlow sign, ultrasonography is not recommended.

Ultrasonography is recommended at 6 weeks of age for selected groups:

  • Breech presentation

  • Girls with positive family history

  • Negative Barlow/Ortolani signs but suspicious physical examination (e.g., adventitial click, thigh asymmetry, apparent limb length inequality)

Hips should be examined at periodic intervals throughout the first year of life and imaging/referral to an orthopedist made for any concerning findings.

Researchers from Children's Hospital, Boston performed a decision analysis on screening for DDH, published in 2009. They used literature review and decision tree analysis. A strategy of universal examination with selective ultrasonography based on physical examination was found to be optimal. This was felt to have the lowest risk of the patient having an arthritic hip at age 60 years.

If you are able to confirm that the patient has developmental dysplasia of the hip, what treatment should be initiated?

If a clinically unstable hip is identified on examination by either the Barlow or Ortolani stress maneuvers, treatment with a Pavlik harness is recommended.

Important: This may be initiated by the primary care provider only if he or she is comfortable with proper fitting of the harness.

Harness treatment is more successful when started earlier, and the child should be seen by a pediatric orthopedist as soon as possible after diagnosis. Close follow-up by a pediatric orthopedist is needed to ensure safe and efficacious use of the Pavlik harness. Once DDH is diagnosed, treatment should be directed by a pediatric orthopedist to ensure safe and effective treatment.

If the hips fail to stabilize in Pavlik harness within the 3-4 weeks  of treatment, it should be discontinued. Children whose hips fail to stabilize in a Pavlik harness may be candidates for abduction bracing if the hips remains clinically reducible. Closed or open reduction may also be indicated for children who fail harness and/or bracing treatment.

What surgical treatments are done for DDH?

Children whose hips fail to stabilize in a Pavlik harness after 1 month will usually require surgical treatment.

Closed reduction with arthrography of the hips will be the first line of surgical management. If the hips can be reduced under anesthesia and have a reasonable zone of stability, a spica cast will be applied to hold the reduction. Duration of spica casting varies.

If a closed reduction cannot be accomplished or there is an insufficient zone of stability, an open reduction will be required. This may be done at the same setting or at a later date based on patient size and surgeon preference. Open reduction can be accomplished through a medial or anterior approach. An advantage of the anterior approach is the ability to perform a capsule repair, something not possible with a medial approach. Medial approach can be done at a younger age (<12 months).

In case of delayed diagnosis into toddler age, a pelvic osteotomy and/or femoral shortening osteotomy may also be done concurrently to improve stability.

What are the adverse effects associated with each treatment option?

Pavlik harness treatment is not without complications. Hip flexion should not be excessive, as femoral nerve palsy may result. Parents should be instructed to evaluate daily for quadriceps function and discontinue harness use if the child can no longer extend the knee spontaneously. The harness may need to be abandoned or adjusted in this case by the treating physician.

Excessive forced abduction should not be held with the harness. This may lead to high pressure on the femoral head and consequent avascular necrosis.

The harness itself can cause abnormal remodeling of the femoral head and acetabulum if the hips fail to reduce in a reasonable amount of time (1 month). Prolonged harness treatment should not be done if the hip does not stabilize within the first month.

It is recommended that the Pavlik harness be applied and monitored only by a trained pediatric orthopedist.

Surgical treatment carries numerous complications as well. Aside from anesthetic complications, avascular necrosis remains the most severe surgical complication. This may occur because of surgical trauma with disruption of the blood supply to the femoral head or excessive abduction in the postoperative spica cast.

What are the possible outcomes of developmental dysplasia of the hip?

DDH outcomes can span from a normal-appearing hip that lasts a lifetime to painful hip dislocation requiring joint replacement. Radiographic findings of dysplasia are identified in many infants after normalization of ultrasound. It is recommended that children treated for DDH be followed by an orthopedic surgeon through skeletal maturity to monitor hip development. Surgical interventions to promote normal femoral head and acetabular development are possible while children still have open triradiate cartilage.

More recently, subtle cases of hip dysplasia are being recognized in adolescents and young adults. These are most often in patients presumed to have had unrecognized mild DDH as infants. New surgical interventions have been shown to successfully preserve the native hip joint; however, long-term ability to defer joint replacement has not been proved.

There are no good longitudinal studies of infants treated nonsurgically for DDH using a Pavlik harness or other brace through skeletal maturity. Long-term results of children with abnormal hip ultrasonographic findings and normal clinical examination are also lacking.

Recent literature has shown reasonable long-term results of open reduction of the hip with pelvic osteotomy for children with surgically treated DDH.

What causes this disease and how frequent is it?

What is the epidemiology of developmental dysplasia of the hip?

True estimates of the incidence of DDH are unknown. Subtle DDH is being recognized more frequently in adolescents and young adults. The true value depends on whether subtle hip instability is considered DDH or a normal finding in the neonate Reported values for DDH range from 0.1%-3% based on whether examination or ultrasonography is used. Ultrasonography detects a higher number of children with abnormality; however, it is unknown whether it is clinically significant abnormality.

The incidence of frank hip dislocation in the neonate is between 0.1% and 0.2% of all live births. DDH is three times more common in girls than in boys. DDH is more common in first-born children. Certain ethnic groups have a higher incidence of DDH. The rate is higher in Eskimos and Native Americans and extremely low in Asians, Africans, and African Americans.

Family history is a risk factor for DDH, with a 6% risk of DDH with one affected sibling, 12% with one affected parent, and 36% with one affected parent and sibling. The exact genetics are not understood, and inheritance is likely multifactorial.

What complications might you expect from the disease or treatment of the disease?

Residual hip dysplasia without dislocation has the potential to cause hip symptoms with aging. If the acetabulum and femoral head do not appropriately remodel following treatment of DDH the abnormal hip joint may cause pain and lead to premature osteoarthritis. Joint replacement in patients with DDH has a greater rate of complications than in primary osteoarthritis. New surgical options that preserve the native hip joint have shown promise in patients with hip dysplasia presenting with symptoms prior to development of osteoarthritis.

DDH with hip dislocation can also lead to hip pain with ageing. Bilateral hip dislocations are much better tolerated than unilateral hip dislocations. Patients with bilateral dislocations often have no symptoms other than an altered gait. Unilateral dislocations frequently cause symptoms due to limb length inequality. The key factor associated with symptoms at adulthood in DDH with hip dislocation is presence of a false acetabulum. Patients without a false articulation are more likely to be pain free. Joint replacement is the treatment of choice for symptomatic patients with untreated DDH and hip dislocation.

Are additional laboratory studies available; even some that are not widely available?

No laboratory studies are useful in the diagnosis of DDH.

How can developmental dysplasia of the hip be prevented?

Avoidance of tight postnatal wrapping or positioning of infants with the hips and knees in a fixed extended position may reduce the incidence of DDH.

Although there is a known family predilection for DDH, the genetics are not yet well understood and genetic counseling is not recommended to prevent DDH.

No nutritional factors have been identified to prevent DDH.

What is the evidence?

Gornitzky, AL, Georgiadis, AG, Seeley, MA, Horn, BD, Sankar, WN. "Does perfusion MRI after closed reduction of developmental dysplasia of the hip reduce the incidence of avascular necrosis". Clin Orthop Relat Res. 2015.

(Use of perfusion MRI after closed reduction and spica cast application in infants with DDH had reduced rates of AVN (4% versus 28%) in a matched cohort comparing those with other imaging techniques such as x-rays or CT scan.)

Graf, R. "Fundamentals of sonographic diagnosis of infant hip dysplasia". J Pediatr Orthop. vol. 4. 1984. pp. 735-40.

(Description of Graf's ultrasonic technique for evaluation of DDH with results in 3500 newborns.)

Grill, F, Bensahel, H, Canadell, J. "The Pavlik harness in the treatment of congenital dislocating hip: report on a multi-center study of the European Pediatric Orthopedic Society". J Pediatr Orthop. vol. 8. 1988. pp. 1-8.

(Greater than 90% success with Pavlik harness treatment is reported from this prospective study from multiple centers in Europe.)

Harcke, HT, Kumar, SJ. "The role of ultrasound in the diagnosis and management of congenital hip dislocation and dysplasia of the hip". J Bone Joint Surg Am. vol. 73. 1991. pp. 622-8.

(Review article of ultrasonographic techniques in the evaluation and screening of DDH.)

Holen, KJ, Tegnander, A, Bredland, T. "Universal or selective screening of the neonatal hip using ultrasound? A prospective randomized trial of 15,529 newborn infants". J Bone Joint Surg Br. vol. 84. 2002. pp. 886-90.

(Randomized controlled trial of universal versus selective screening for DDH in newborns. Children were followed for 6-11 years after screening. No significant difference in the rate of late diagnosis of DDH was observed between the two groups.)

Mulpuri, K, Song, KM, Gross, RH, Tebor, GB, Otsuka, NY, Lubicky, JP. "The American Academy of Orthopaedic Surgeons evidence-based guidelines on detection and nonoperative management of pediatric developmental dysplasia of the hip in infants up to six months of age". J Bone Joint Surg Am. vol. 97. 2015. pp. 1717-8.

(Multi-speciality endorsed evidence based guidelines for detection and non-operative management of DDH in infants under six months of age.)

Mahan, ST, Katz, JN, Kim, YJ. "To screen or not to screen? A decision analysis of the utility of screening for developmental dysplasia of the hip". J Bone Joint Surg Am. vol. 91. 2009. pp. 1705-19.

Pavlik, A. "The functional method of treatment using a harness with stirrups as the primary method of conservative therapy for infants with congenital dislocation of the hip.1957". Clin Orthop Relat Res. vol. 281. 1992. pp. 4-10.

(Initial description of the results of Pavlik harness treatment. An 84% success rate was described.)

Rosendahl, K, Markestad, T, Lie, RT. "Ultrasound screening for developmental dysplasia of the hip in the neonate: the effect on treatment rate and prevalence of late cases". Pediatrics. vol. 94. 1994. pp. 47-57.

(Randomized controlled trial of general versus selective versus no ultrasonographic screening for DDH in newborns. No significant benefit to general screening was observed with increased treatment rates and follow-up visits in the general and selective screening groups.)

Sankar, WN, Nduaguba, A, Flynn, JM. "Ilfeld abduction orthosis is an effective second-line treatment after failure of Pavlik harness for infants with developmental dysplasia of the hip". J Bone Joint Surg Am. vol. 97. 2015. pp. 292-7.

(Abduction brace was found to have equal treatment success to closed reduction and spica cast application in infants with DDH who failed initial treatment with Pavlik harness.)

Sarkissian, EJ, Sankar, WN, Zhu, X, Wu, CH, Flynn, JM. "Radiographic follow-up of DDH in infants: Are x-rays needed after a normalized ultrasound". J Pediatr Orthop. vol. 35. 2015. pp. 551-5.

(Evaluation of x-ray findings at 6 mo and 12mo of age in children with DDH who had normalization of ultrasound found dysplastic radiographic findings in 17% of children at 6 months and 33% at 12 months in those untreated at 6 months of age.)

Shorter, D, Hong, T, Osborn, DA. "Cochrane review: Screening programmes for developmental dysplasia of the hip in newborn infants". Evid Based Child Health. vol. 8. 2013. pp. 11-54.

(Cochrane review showing that optimal screening strategy for DDH has not been established. Neither universal nor targeted screening has been shown to effectively reduce late diagnosis or need for surgery for DDH.)

Thallinger, C, Pospischill, R, Ganger, R, Radler, C, Krall, C, Grill, F. "Long-term results of a nationwide general ultrasound screening system for developmental disorders of the hip: the Austrian hip screening program". J Child Orthop. vol. 8. 2014. pp. 3-10.

(Results of general ultrasounds screening of all newborns in Austria from 1992-2008 found the rate of children requiring pelvic surgery to treat DDH decreased 46% and hospital admissions for treatment of DDH decreased from 9.5 to 3.6 per 1,000 live births compared to historical data prior to 1992.)

"US Preventive Services Task Force. Screening for developmental dysplasia of the hip; recommendation statement". Pediatrics. vol. 117. 2006. pp. 898-902.

(The US Preventive Services Task Force concludes that evidence is insufficient to recommend routine screening for DDH in infants as a means to prevent adverse outcomes.)

Weinstein, SL. "Natural history of congenital hip dislocation and hip dysplasia". Clin Orthop Relat Res. vol. 225. 1987. pp. 62-76.

(Review article discussing the natural history of DDH from dysplasia to frank dislocation.)

Ongoing controversies regarding etiology, diagnosis, treatment

There remains controversy on the appropriate screening modality for DDH. In particular, the role of ultrasonography as a selective or universal screening tool continues to be debated. Advocates for universal ultrasonographic screening (as is done in several countries in Europe) point to the high accuracy of ultrasonography in diagnosing DDH with dislocation and especially in diagnosing milder DDH with only ultrasonographic abnormalities.

Those favoring selective ultrasonography based on abnormal examination or risk factors believe universal ultrasonography leads to high levels of treatment of hip dysplasia with only ultrasonographic abnormalities (without dislocation) in children in whom normalization of their hips may have otherwise occurred without intervention. Furthermore, there is controversy in the literature about whether or not universal ultrasonographic detection leads to any improvement in the rate of "missed" DDH. Some papers demonstrate equivalent rates of surgery for DDH with universal versus selective ultrasonographic screening. A recent Cochrane review concluded that optimal screening strategy cannot be determined based on current evidence.

Conservative treatment with the Pavlik harness remains the most widely used treatment for DDH in infants. Abduction bracing as primary treatment in newborns instead of Pavlik harness has shown promising results and continues to be actively studied and compared to results of Pavlik harness treatment.

Surgical treatment of DDH remains frequently debated. Topics of controversy include the age at which to intervene surgically, medial versus anterior surgical approach, and need for associated pelvic osteotomy.

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