Developmental dysplasia of the hip

June 1, 2017

Developmental dysplasia of the hip (DDH) refers to a spectrum of abnormalities that range in severity from mild instability to frank dislocation. The vast majority of clinical and anatomic hip abnormalities identified in early infancy resolve spontaneously. Left untreated, however, a hip that is persistently unstable and anatomically abnormal can lead to functional limitations, pain, and premature degenerative changes.

Developmental dysplasia of the hip (DDH) refers to a spectrum of abnormalities that range in severity from mild instability to frank dislocation. The vast majority of clinical and anatomic hip abnormalities identified in early infancy resolve spontaneously.1 Left untreated, however, a hip that is persistently unstable and anatomically abnormal can lead to functional limitations, pain, and premature degenerative changes.2,3

Early detection of significant hip dysplasia allows for early intervention that is nonsurgical and likely to afford the best long-term outcome.2 Because DDH is asymptomatic until a child begins walking and occurs mostly in the absence of risk factors other than female sex, early identification relies on newborn screening and follow-up surveillance through physical examination and selective use of imaging studies.

In 2000, the American Academy of Pediatrics (AAP) issued its first clinical practice guideline on DDH and an accompanying technical report.4,5 Titled “Early detection of developmental dysplasia of the hip,” the guideline’s objective was to reduce the number of dislocated hips detected later in infancy and childhood, and it promoted screening as a primary care function.

In November 2016, the AAP released an updated clinical report titled “Evaluation and referral for developmental dysplasia of the hip in infants.”2 The 2016 clinical report was written to provide clinicians with literature-based direction on screening, surveillance, and referral for orthopedic consultation to prevent and/or detect a dislocated hip by 6 to 12 months of age in an otherwise healthy child. Developments providing impetus for the report included emerging evidence supporting observation rather than treatment of minor ultrasonographic hip variations, issuing of an “inconclusive” rating for the usefulness of DDH screening by the US Preventive Services Task Force (USPSTF), and release of an American Academy of Orthopaedic Surgeons (AAOS) evidence-based clinical practice guideline on DDH detection and management in infants aged 0 to 6 months.1,2,6

The AAP clinical report presents evidence and controversies surrounding diagnosis and management of DDH, and it contains 10 statements on best practices and state of the art that are based on literature review, expert opinion, policies and position statements of the AAP and the Pediatric Orthopaedic Society of North America (POSNA), and the AAOS clinical practice guideline.1,3,4 The guidance provided by the clinical report is mostly the same as that found in the AAP’s 2000 clinical practice guideline. The 2016 document differs, however, in its recommendations on risk factors that may prompt an imaging study.7 In addition, it brings forth the concept of hip-healthy methods of swaddling and includes a discussion of medicolegal risk to the pediatrician.

Practitioners are encouraged to read the entire clinical report on DDH. This article presents its recommendations with some related information.

DDH detection

Screening/surveillance

The AAP promotes screening/surveillance physical examinations for DDH as a primary care function, and the clinical report notes that newborn and periodic surveillance are also endorsed by the POSNA, the Canadian DDH Task Force, and the AAOS.1-3,8

The clinical report addresses the controversial USPSTF “inconclusive”rating on the usefulness of DDH screening.6 In stating that “evidence is insufficient to recommend routine screening for DDH in infants as a means to prevent adverse outcomes,” the USPSTF noted that most hip abnormalities identified in newborns resolve spontaneously and that screening tests for DDH have limited accuracy. In addition, it cited risks of avascular necrosis resulting from surgical and nonsurgical interventions for DDH and psychological consequences or stresses accompanying early diagnosis and intervention as potential harms of screening. As reviewed in the clinical report, these concerns are negated by evidence from published studies that were not included in the USPSTF report.

Physical examination

Physical examination for DDH should be performed in newborns and at well-care child visits through age 9 months or until the child begins walking to detect significant hip dysplasia.

The Ortolani maneuver (Table 1), which elicits the sensation of a dislocated hip reducing, is considered the most important clinical test for detecting hip dysplasia in infants aged 0 to 3 months.2 After age 3 months, a reducible hip becomes stabilized in the dislocated position and limitation of abduction is considered the most reliable sign of DDH.4

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The Barlow maneuver (Table 1), which involves gentle adduction to produce subluxation or dislocation of a reduced femoral head, is another test for assessing hip instability in newborns. The Barlow maneuver, however, only identifies laxity or instability and it is considered to be less clinically significant than the Ortolani maneuver. As explained in the clinical report, mild hip instability may represent normal developmental variation, and hips that are Barlow-positive in the first few weeks of life resolve spontaneously.

The physical examination for DDH should also look for unequal leg length and asymmetry in the position or number of thigh and/or buttock (gluteal) creases. Examiners should be aware, however, that leg length discrepancy may be absent when DDH is bilateral, which occurs in up to 37% of affected cases.9,10 In addition, asymmetry of skinfolds is a nonspecific and common finding in infants.11

NEXT: Imaging

 

Imaging

In the clinical report, the AAP recommends against routine use of ultrasound as a screening modality for DDH and suggests that imaging with ultrasonography or radiography, depending on the child’s age, be used as an adjunctive screening tool in selected situations that take into account risk factors or suspicious physical examination.

The report states that hip ultrasonography can be considered between the ages of 6 weeks and 6 months for “high-risk” infants who lack physical findings of DDH (see Table 2 and section on risk factors).

For accurate interpretation, the hip ultrasonogram should be reviewed by an experienced, trained examiner per American Institute of Ultrasound in Medicine and the American College of Radiology guidelines. The clinical report notes that regional variability of ultrasonographic imaging quality can be a factor in undertreatment or overtreatment of DDH.2

Using ultrasound as a diagnostic tool prior to age 6 weeks is not recommended because it has a high false-positive rate and may detect abnormalities that spontaneously resolve. The clinical report notes, however, that ultrasound may be used earlier to guide treatment of an Ortolani-positive hip.

As explained in the clinical report, use of radiography as an imaging tool should be deferred until children are aged at least 4 months when the femoral is ossified. Then, radiography (anteroposterior and frog pelvis views) can be considered for high-risk infants without physical findings or for children with positive clinical findings.

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Although ultrasound can also be used for imaging children aged 4 to 6 months, radiography has advantages of wider access, a lower false-positive rate, and lower cost. The drawback of radiography versus ultrasonography is exposure to a very low dose of radiation. In the absence of evidence favoring one imaging modality over the other, the clinical report recommends choice be based on local conditions and the availability of experienced, trained pediatric hip sonographers.

NEXT: Risk factors

 

Risk factors

The clinical report notes that most DDH occurs in children without risk factors and that “high risk” is a relative and controversial term. Among features that have been identified as risk factors for DDH, breech presentation in the third trimester and positive family history (including hip replacement in a close relative when aged 40 years or younger) may be the most important.1,2 Frank beech presentation in a girl has the highest risk, and breech position toward the end of pregnancy has greater importance than breech delivery.2,4

Orthopedic referral and treatment

There is strong support from available evidence for treating hip dislocation, identified by a positive Ortolani test result, and for initially observing milder early forms of dysplasia and instability (positive Barlow test result) with periodic physical examination and imaging if deemed appropriate. Presence of a positive Barlow test is not an indication for orthopedic referral. Infants with a positive Barlow test should be followed and only referred to an orthopedist if clinical instability persists.

There is insufficient evidence for recommending treatment versus observation in a specific case of minor ultrasonographic variation. In this setting, the approach to care should be determined through shared decision making.

Treatment for hip dislocation should be performed by an orthopedist whereas follow-up observation, when indicated, can be performed by the pediatrician or the orthopedist.

Indications for referral to an orthopedic specialist are: 1) unstable (positive Ortolani test result) or dislocated hip on physical examination, and 2) limited or asymmetric hip abduction in a child aged 4 weeks or older. Relative indications for referral include presence of DDH risk factors, questionable findings on physical examination, and any pediatrician or parental concern.

Imaging (ultrasonography or radiography) is not required for orthopedic referral. The clinical report notes that treatment of neonatal DDH is not an emergency, and it is not necessary to begin intervention before the child is released from the hospital.2 A newborn with a positive Ortolani test should be seen by an orthopedist within several weeks after hospital discharge. The AAOS guideline on DDH, which pertains to infants aged 6 months or younger, notes there is limited evidence supporting either immediate or delayed (2 to 9 weeks) brace treatment for hips with a positive instability exam.1

Preventing DDH

The clinical report cautions against tight swaddling of the lower extremities with the hips adducted, and notes that “safe” swaddling, which does not restrict hip motion, minimizes the risk of DDH.2 A video on safe swaddling is available at: bit.ly/healthy-swaddling-video. The 2016 clinical report also cites a position statement on swaddling and DDH issued by the AAP, the POSNA, the International Hip Dysplasia Institute, the AAOS, the US Bone and Joint Initiative (USBJI), and Shriners Hospitals for Children that promotes “hip-healthy swaddling” when parents decide to swaddle their infant.12

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The report also notes that there is no high-level evidence that milder forms of dysplasia can be prevented by screening and early treatment and that no screening program can completely eliminate the risk of late-presenting DDH needing treatment.

Medicolegal risk

Recognizing that practitioners are likely to be concerned about liability in cases of undetected or late-developing DDH and the potential for this concern to trigger overdiagnosis and overtreatment, the clinical report includes a discussion of medicolegal risk. Suggested strategies are summarized in Table 3.4

REFERENCES

1. American Academy of Orthopaedic Surgeons. Detection and nonoperative management of pediatric developmental dysplasia of the hip in infants up to six months of age. Evidence-based clinical practice guideline. Rosemont, IL: American Academy of Orthopaedic Surgeons; 2014. Available at: http://www.aaos.org/research/guidelines/DDHGuidelineFINAL.pdf. Accessed May 17, 2017.

2. Shaw BA, Segal LS; Section on Orthopaedics. Evaluation and referral for developmental dysplasia of the hip in infants. Pediatrics. 2016;138(6):e20163107.

3. Schwend RM, Schoenecker P, Richards BS, Flynn JM, Vitale M; Pediatric Orthopaedic Society of North America. Screening the newborn for developmental dysplasia of the hip: now what do we do? J Pediatr Orthop. 2007;27(6):607-610.

4. 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.

5. Lehmann HP, Hinton R, Morello P, Santoli J. Developmental dysplasia of the hip practice guideline: technical report. Committee on Quality Improvement, and Subcommittee on Developmental Dysplasia of the Hip. Pediatrics. 2000;105(4):e57.

6. US Preventive Services Task Force. Screening for developmental dysplasia of the hip: recommendation statement. Pediatrics. 2006;117(3):898-902.

7. Shaw BA, Segal LS. Report recommends changes in screening for developmental dysplasia of the hip. AAP News. Available at: http://www.aappublications.org/news/2016/11/21/DDH112116. Published November 21, 2016. Accessed May 17, 2017.

8. Patel H; Canadian Task Force on Preventive Health Care. Preventive health care, 2001 update: screening and management of developmental dysplasia of the hip in newborns. CMAJ. 2001;164(12):1669-1677.

9. Rosenfeld SB. Developmental dysplasia of the hip: clinical features and diagnosis. UpToDate. Available at: https://www.uptodate.com/contents/developmentaldysplasia-of-the-hip-clinical-features-and-diagnosis. Updated February 15, 2017. Accessed May 17, 2017

10. Dunn PM. Perinatal observations on the etiology of congenital dislocation of the hip. Clin Orthop Relat Res. 1976;(119):11-22. Available at: http://journals.lww.com/corr/Abstract/1976/09000/Perinatal_Observations_on_the_Etiology_of.4.aspx. Accessed May 17, 2017.

11. Ando M, Gotoh E. Significance of inguinal folds for diagnosis of congenital dislocation of the hip in infants aged three to four months. J Pediatr Orthop. 1990;10(3):331-334.

12. American Academy of Pediatrics (AAP), Pediatric Orthopaedic Society of North America (POSNA), International Hip Dysplasia Institute (IHDI), American Academy of Orthopaedic Surgeons (AAOS), US Bone and Joint Initiative (USBJI), Shriners Hospitals for Children. Position statement: Swaddling and developmental hip dysplasia. Rosemont, IL: Pediatric Orthopaedic Society of North America; 2015. Available at: https://posna.org/POSNA/media/Documents/Position Statements/SwaddlingPositionStatementApril2015.pdf. Accessed May 17, 2017.