A Click Is Not a Clunk: Developmental Dysplasia of the Hip in a Newborn

IN THIS ARTICLE

• Diagnosis
• Management
• Newborn hip evaluation algorithm

Developmental dysplasia of the hip (DDH), previously known as congenital dislocation of the hip, follows a spectrum of irregular anatomic hip development spanning from acetabular dysplasia to irreducible dislocation at birth. Early detection is critical to improve the overall prognosis. Prompt diagnosis requires understanding of potential risk factors, proficiency in physical examination techniques, and implementation of appropriate screening tools when indicated. Although current guidelines direct timing for physical exam screenings, imaging, and treatment, it is ultimately up to the provider to determine the best course of action on a case-by-case basis. This article provides a review of these topics and more.

CURRENT GUIDELINES

In 2000, the American Academy of Pediatrics (AAP) developed guidelines for detection of hip dysplasia, including recommendation of relevant physical exam screenings for all newborns.¹ In 2007, the Pediatric Orthopaedic Society of North America (POSNA) encouraged providers to follow the AAP guidelines with a continued recommendation to perform newborn screening for hip instability and routine follow-up evaluations until the child achieves walking.² The American Academy of Orthopaedic Surgeons (AAOS) also established clinical guidelines in 2014 that are endorsed by both AAP and POSNA.³ These guidelines support routine clinical screening; research evaluated infants up to 6 months old, however, limiting the recommendations to that age-group.

Failure to treat DDH early has been associated with serious negative sequelae that include chronic pain, degenerative arthritis, postural scoliosis, and early gait disturbances.⁴ Primary care providers are expected to perform thorough newborn hip exams with associated specialized tests (ie, Ortolani and Barlow, which are discussed in “Physical exam”) at each routine follow-up. Heightened clinical suspicion and risk factor awareness are key for primary care providers to promptly identify patients requiring orthopedic referral. With early diagnosis, a removable soft abduction brace can be applied as the initial treatment. When treatment is delayed, however, closed reduction under anesthesia or complex surgical intervention may be required.

EPIDEMIOLOGY

The etiology for DDH remains unknown. Hip dysplasia typically presents unilaterally but can also occur bilaterally. DDH is more likely to affect the left hip than the right.⁵

Reported incidence varies, ranging from 0.06 to 76.1 per 1,000 live births, and is largely affected by race and geographic location.⁵ Incidence is higher in countries where routine screening is required, by either physical examination or ultrasound (1.6 to 28.5 and 34.0 to 60.3 per 1,000, respectively), compared with countries not requiring routine screening (1.3 per 1,000). This may suggest that the majority of hip dysplasia cases are transient and resolve spontaneously without treatment.^6,7

RISK FACTORS AND PATIENT HISTORY

Known risk factors for DDH include breech presentation (see Figure 1), positive family history, and female gender.^5,8-10 Female infants are eight times more likely than males to develop DDH.¹⁰ Firstborn status is also recognized as an associated risk factor, which may be attributable to space constraints in utero. This hypothesis is further supported by the relative DDH-protective effect of prematurity and low birth weight. Other potential risk factors include advanced maternal age, birth weight that is high for gestational age, decreased hip abduction, and joint laxity. However, the majority of patients with hip dysplasia have no identifiable risk ­factors.^3,5,9,11,12

Swaddling, which often maintains the hips in an adducted and/or extended position, has also been strongly associated with hip dysplasia.^5,13 Multiple organizations, including the AAOS,AAP, POSNA, and the International Hip Dysplasia Institute, have developed or endorsed hip-healthy swaddling recommendations to minimize the risk for DDH in swaddled infants.^13-15 Such practices allow the infant’s legs to bend up and out at the hips, promoting free hip movement, flexion, and abduction.^13,15 Swaddling has demonstrated multiple benefits (including improved sleep and relief of excessive crying¹³) and continues to be recommended by many US providers; however, those caring for infants at risk for DDH should avoid traditional swaddling and/or practice hip-healthy swaddling techniques.^10,13,14 Early diagnosis starts with the clinician’s knowledge of DDH risk factors and the recommended screening protocols. The presence of multiple risk factors will increase the likelihood of this condition and should lower the clinician’s threshold for ordering additional screening, regardless of hip exam findings.

PHYSICAL EXAM

Both AAP and AAOS guidelines recommend clinical screening for DDH with physical exam in all newborns.^1,3 A head-to-toe musculoskeletal exam is warranted during the initial evaluation of every newborn in order to assess for any known DDH-associated conditions, which may include neuromuscular disorders, torticollis, and metatarsus adductus.⁵

Initial evaluation of an infant with DDH may reveal nonspecific findings, including asymmetric skin folds and limb-length inequality. The Galeazzi sign should be sought by aligning flexed knees with the child in the supine position and assessing for uneven knee heights (see Figure 2). Unilateral posterior hip dislocation or femoral shortening represents a positive Galeazzi sign.¹⁶ Joint laxity and limited hip abduction have also been associated with DDH.^1,10

Barlow and Ortolani exams are more specific to DDH and should be completed at newborn screening and each subsequent well-baby exam.¹ The Barlow maneuver is a provocative test with flexion, adduction, and posterior pressure through the infant’s hip (Figure 3). A palpable clunk during the Barlow maneuver indicates positive instability with posterior displacement. The Ortolani test is a reductive maneuver requiring abduction with posterior pressure to lift the greater trochanter (Figure 4). A clunk sensation with this test is positive for reduction of the hip.

The infant’s diaper should be removed during the hip evaluation. These exams are more reliable when each hip is evaluated separately with the pelvis stabilized.¹⁰ All physical exam findings must be carefully documented at each encounter.^1,17

It is critical for the examiner to understand the appropriate technique and potential results when conducting each of these specialized hip exams. A true positive finding is the clunking sensation that occurs with the dislocation or relocation of the affected hip; this finding is better felt than heard. In contrast, a benign hip click with these maneuvers is a more subtle sensation—typically, a soft-tissue snapping or catching—and is not diagnostic of DDH. A click is not a clunk and is not indicative of DDH.^1,3

DDH may present later in infancy or early childhood; therefore, DDH should remain within the differential diagnosis for gait asymmetry, unequal hip motion, or limb-length discrepancy. It may be beneficial to continue to evaluate for these developments during routine exams as part of a thorough pediatric musculoskeletal assessment, particularly in patients with documented risk factors for DDH.^1,3,4 Delay in diagnosis of DDH, it should be noted, is a relatively common complaint in pediatric medical malpractice lawsuits; until the early 2000s, this condition represented about 75% of claims in one medical malpractice database.The decrease in claims has been attributed to better awareness and earlier diagnosis of DDH. ¹⁷

Continue for the diagnosis >>